658 results on '"Yiannoutsos, Constantin T"'
Search Results
2. Marginal Regression on Transient State Occupation Probabilities with Clustered Multistate Process Data
- Author
-
Zhou, Wenxian, Bakoyannis, Giorgos, Zhang, Ying, and Yiannoutsos, Constantin T
- Subjects
Statistics - Methodology - Abstract
Clustered multistate process data are commonly encountered in multicenter observational studies and clinical trials. A clinically important estimand with such data is the marginal probability of being in a particular transient state as a function of time. However, there is currently no method for nonparametric marginal regression analysis of these probabilities with clustered multistate process data. To address this problem, we propose a weighted functional generalized estimating equations approach which does not impose Markov assumptions or assumptions regarding the structure of the within-cluster dependence, and allows for informative cluster size (ICS). The asymptotic properties of the proposed estimators for the functional regression coefficients are rigorously established and a nonparametric hypothesis testing procedure for covariate effects is proposed. Simulation studies show that the proposed method performs well even with a small number of clusters, and that ignoring the within-cluster dependence and the ICS leads to invalid inferences. The proposed method is used to analyze data from a multicenter clinical trial on recurrent or metastatic squamous-cell carcinoma of the head and neck with a stratified randomization design.
- Published
- 2022
3. Contraceptive implant use duration is not associated with breakthrough pregnancy among women living with HIV and using efavirenz: a retrospective, longitudinal analysis
- Author
-
Stalter, Randy M, Amorim, Gustavo, Mocello, A Rain, Jakait, Beatrice, Shepherd, Bryan E, Musick, Beverly, Bernard, Caitlin, Bukusi, Elizabeth A, Wools‐Kaloustian, Kara, Cohen, Craig R, Yiannoutsos, Constantin T, Patel, Rena C, and consortium, the Implant Efavirenz Study Group and the East Africa IeDEA regional
- Subjects
Infectious Diseases ,Prevention ,Bioengineering ,HIV/AIDS ,Contraception/Reproduction ,Infection ,Good Health and Well Being ,Adolescent ,Adult ,Alkynes ,Benzoxazines ,Contraceptive Agents ,Cyclopropanes ,Female ,HIV Infections ,Humans ,Levonorgestrel ,Middle Aged ,Nevirapine ,Pregnancy ,Retrospective Studies ,Young Adult ,HIV ,women living with HIV ,contraception ,efavirenz ,implant ,pregnancy ,Implant/Efavirenz Study Group and the East Africa IeDEA regional consortium ,Clinical Sciences ,Public Health and Health Services ,Other Medical and Health Sciences - Abstract
IntroductionContraceptive implants containing etonogestrel and levonorgestrel have emerged as popular contraceptive options among women in areas of high HIV burden in sub-Saharan Africa. However, recent pharmacokinetic data have shown drug-drug interactions between implants and efavirenz-containing antiretroviral therapy (ART), reducing the effectiveness of the implants. Here, we evaluated pregnancy incidence in 6-month intervals following implant initiation among women using efavirenz and contraceptive implants to assess whether the risk of breakthrough pregnancy is higher after specific periods of implant use.MethodsWe used data from a retrospective longitudinal analysis of women living with HIV ages 18-45 years in western Kenya who attended HIV-care facilities between 2011 and 2015. We used Cox proportional hazard models to compute hazard ratios (HRs) for breakthrough pregnancy by implant type and ART regimen. Depending on the model, we adjusted for socio-demographic and clinical factors, programme, site and interaction between calendar time and ART regimen. We utilized inverse probability weights (IPWs) to account for three sampling phases (electronic medical record [EMR], chart review and phone interview) and calculated overall parameter estimates.ResultsWomen contributed 14,768 woman-years from the largest sampling phase (EMR). The median age was 31 years. Women used etonogestrel implants for 26-69% of the time and levonorgestrel implants for 7-31% of the time, depending on the sampling phase. Women used efavirenz, nevirapine or no ART for 27-33%, 40-46% and 15-26% of follow-ups, respectively. When combining sampling phases, there was little evidence to suggest that the relative hazard of pregnancy among efavirenz-containing ART users relative to nevirapine-containing ART changed with length of time on implants: IPW-adjusted HR of 3.1 (CI: [1.5; 6.4]) at 12 months, 3.4 (CI: [1.8; 6.3]) at 24 months, 3.8 (CI: [1.9; 7.7]) at 36 months and 4.2 (CI: [1.6; 11.1]) at 48 months (interaction p-value = 0.88). Similarly, no significant change in HRs over time was found when comparing women not using ART to nevirapine-containing ART users (interaction p-value = 0.49).ConclusionsWe did not find evidence to suggest implants being more fallible from drug-drug interactions with efavirenz at later time intervals of implant use. Thus, we would not recommend shortening the duration of implant use or replacing implants sooner when concomitantly used with efavirenz.
- Published
- 2022
4. Semiparametric Marginal Regression for Clustered Competing Risks Data with Missing Cause of Failure
- Author
-
Zhou, Wenxian, Bakoyannis, Giorgos, Zhang, Ying, and Yiannoutsos, Constantin T.
- Subjects
Statistics - Methodology - Abstract
Clustered competing risks data are commonly encountered in multicenter studies. The analysis of such data is often complicated due to informative cluster size, a situation where the outcomes under study are associated with the size of the cluster. In addition, cause of failure is frequently incompletely observed in real-world settings. To the best of our knowledge, there is no methodology for population-averaged analysis with clustered competing risks data with informative cluster size and missing causes of failure. To address this problem, we consider the semiparametric marginal proportional cause-specific hazards model and propose a maximum partial pseudolikelihood estimator under a missing at random assumption. To make the latter assumption more plausible in practice, we allow for auxiliary variables that may be related to the probability of missingness. The proposed method does not impose assumptions regarding the within-cluster dependence and allows for informative cluster size. The asymptotic properties of the proposed estimators for both regression coefficients and infinite-dimensional parameters, such as the marginal cumulative incidence functions, are rigorously established. Simulation studies show that the proposed method performs well and that methods that ignore the within-cluster dependence and the informative cluster size lead to invalid inferences. The proposed method is applied to competing risks data from a large multicenter HIV study in sub-Saharan Africa where a significant portion of causes of failure is missing.
- Published
- 2021
5. Pregnancies among women living with HIV using contraceptives and antiretroviral therapy in western Kenya: a retrospective, cohort study
- Author
-
Patel, Rena C, Amorim, Gustavo, Jakait, Beatrice, Shepherd, Bryan E, Mocello, A Rain, Musick, Beverly, Bernard, Caitlin, Onono, Maricianah, Bukusi, Elizabeth A, Wools-Kaloustian, Kara, Cohen, Craig R, and Yiannoutsos, Constantin T
- Subjects
Reproductive Medicine ,Biomedical and Clinical Sciences ,Health Sciences ,HIV/AIDS ,Infectious Diseases ,Bioengineering ,Clinical Research ,Prevention ,Contraception/Reproduction ,Reproductive health and childbirth ,Good Health and Well Being ,Cohort Studies ,Contraceptive Agents ,Female ,HIV Infections ,Humans ,Kenya ,Pregnancy ,Retrospective Studies ,HIV ,Women living with HIV ,Contraception ,Efavirenz ,Implant ,Implant/Efavirenz Study Group and the East Africa IeDEA Regional Consortium ,Medical and Health Sciences ,General & Internal Medicine ,Biomedical and clinical sciences ,Health sciences - Abstract
BackgroundPreventing unintended pregnancies is paramount for women living with HIV (WLHIV). Previous studies have suggested that efavirenz-containing antiretroviral therapy (ART) reduces contraceptive effectiveness of implants, but there are uncertainties regarding the quality of the electronic medical record (EMR) data used in these prior studies.MethodsWe conducted a retrospective, cohort study of EMR data from 2011 to 2015 among WLHIV of reproductive age accessing HIV care in public facilities in western Kenya. We validated a large subsample of records with manual chart review and telephone interviews. We estimated adjusted incidence rate ratios (aIRRs) with Poisson regression accounting for the validation sampling using inverse probability weighting and generalized raking.ResultsA total of 85,324 women contributed a total of 170,845 women-years (w-y) of observation time; a subset of 5080 women had their charts reviewed, and 1285 underwent interviews. Among implant users, the aIRR of pregnancy for efavirenz- vs. nevirapine-containing ART was 1.9 (95% CI 1.6, 2.4) using EMR data only and 3.2 (95% CI 1.8, 5.7) when additionally using both chart review and interview validated data. Among efavirenz users, the aIRR of pregnancy for depomedroxyprogesterone acetate (DMPA) vs. implant use was 1.8 (95% CI 1.5, 2.1) in EMR only and 2.4 (95% CI 1.0, 6.1) using validated data.ConclusionPregnancy rates are higher when contraceptive implants are concomitantly used with efavirenz-containing ART, though rates were similar to leading alternative contraceptive methods such as DMPA. Our data provides policymakers, program staff, and WLHIV greater confidence in guiding their decision-making around contraceptive and ART options. Our novel, 3-phase validation sampling provides an innovative tool for using routine EMR data to improve the robustness of data quality.
- Published
- 2021
6. Self-transfers, Hospital Admissions and Mortality Among Children and Adolescents Lost to Follow-up From Antiretroviral Therapy Programs in the Western Cape, South Africa Between 2004 and 2019: Linkage to Provincial Records
- Author
-
Nyakato, Patience, Boulle, Andrew, Wood, Robin, Eley, Brian, Rabie, Helena, Egger, Matthias, Yiannoutsos, Constantin T., Davies, Mary-Ann, and Cornell, Morna
- Published
- 2024
- Full Text
- View/download PDF
7. Compartmentalization of cerebrospinal fluid inflammation across the spectrum of untreated HIV-1 infection, central nervous system injury and viral suppression
- Author
-
Gisslen, Magnus, Keating, Sheila M, Spudich, Serena, Arechiga, Victor, Stephenson, Sophie, Zetterberg, Henrik, Di Germanio, Clara, Blennow, Kaj, Fuchs, Dietmar, Hagberg, Lars, Norris, Philip J, Peterson, Julia, Shacklett, Barbara L, Yiannoutsos, Constantin T, and Price, Richard W
- Subjects
Medical Microbiology ,Biomedical and Clinical Sciences ,Immunology ,HIV/AIDS ,Neurosciences ,Clinical Research ,Pediatric ,Acquired Cognitive Impairment ,Pediatric AIDS ,Brain Disorders ,Infectious Diseases ,Evaluation of treatments and therapeutic interventions ,2.1 Biological and endogenous factors ,Aetiology ,6.1 Pharmaceuticals ,Inflammatory and immune system ,Infection ,Good Health and Well Being ,Adult ,Anti-Retroviral Agents ,Antiretroviral Therapy ,Highly Active ,Biomarkers ,CD4-Positive T-Lymphocytes ,CD8-Positive T-Lymphocytes ,Central Nervous System ,Cross-Sectional Studies ,Female ,HIV Infections ,HIV-1 ,Humans ,Inflammation ,Leukocyte Count ,Male ,Middle Aged ,Neurofilament Proteins ,RNA ,Viral ,Serum Albumin ,Sustained Virologic Response ,General Science & Technology - Abstract
ObjectiveTo characterize the evolution of central nervous system (CNS) inflammation in HIV-1 infection applying a panel of cerebrospinal fluid (CSF) inflammatory biomarkers to grouped subjects representing a broad spectrum of systemic HIV-1 immune suppression, CNS injury and viral control.MethodsThis is a cross-sectional analysis of archived CSF and blood samples, assessing concentrations of 10 functionally diverse soluble inflammatory biomarkers by immunoassays in 143 HIV-1-infected subjects divided into 8 groups: untreated primary HIV-1 infection (PHI); four untreated groups defined by their blood CD4+ T lymphocyte counts; untreated patients presenting with subacute HIV-associated dementia (HAD); antiretroviral-treated subjects with ≥1 years of plasma viral suppression; and untreated elite controllers. Twenty HIV-1-uninfected controls were included for comparison. Background biomarkers included blood CD4+ and CD8+ T lymphocytes, CSF and blood HIV-1 RNA, CSF white blood cell (WBC) count, CSF/blood albumin ratio, CSF neurofilament light chain (NfL), and CSF t-tau.FindingsHIV-1 infection was associated with a broad compartmentalized CSF inflammatory response that developed early in its course and changed with systemic disease progression, development of neurological injury, and viral suppression. CSF inflammation in untreated individuals without overt HAD exhibited at least two overall patterns of inflammation as blood CD4+ T lymphocytes decreased: one that peaked at 200-350 blood CD4+ T cells/μL and associated with lymphocytic CSF inflammation and HIV-1 RNA concentrations; and a second that steadily increased through the full range of CD4+ T cell decline and associated with macrophage responses and increasing CNS injury. Subacute HAD was distinguished by a third inflammatory profile with increased blood-brain barrier permeability and robust combined lymphocytic and macrophage CSF inflammation. Suppression of CSF and blood HIV-1 infections by antiretroviral treatment and elite viral control were associated with reduced CSF inflammation, though not fully to levels found in HIV-1 seronegative controls.
- Published
- 2021
8. Semiparametric regression and risk prediction with competing risks data under missing cause of failure
- Author
-
Bakoyannis, Giorgos, Zhang, Ying, and Yiannoutsos, Constantin T.
- Subjects
Statistics - Methodology - Abstract
The cause of failure in cohort studies that involve competing risks is frequently incompletely observed. To address this, several methods have been proposed for the semiparametric proportional cause-specific hazards model under a missing at random assumption. However, these proposals provide inference for the regression coefficients only, and do not consider the infinite dimensional parameters, such as the covariate-specific cumulative incidence function. Nevertheless, the latter quantity is essential for risk prediction in modern medicine. In this paper we propose a unified framework for inference about both the regression coefficients of the proportional cause-specific hazards model and the covariate-specific cumulative incidence functions under missing at random cause of failure. Our approach is based on a novel computationally efficient maximum pseudo-partial-likelihood estimation method for the semiparametric proportional cause-specific hazards model. Using modern empirical process theory we derive the asymptotic properties of the proposed estimators for the regression coefficients and the covariate-specific cumulative incidence functions, and provide methodology for constructing simultaneous confidence bands for the latter. Simulation studies show that our estimators perform well even in the presence of a large fraction of missing cause of failures, and that the regression coefficient estimator can be substantially more efficient compared to the previously proposed augmented inverse probability weighting estimator. The method is applied using data from an HIV cohort study and a bladder cancer clinical trial.
- Published
- 2018
- Full Text
- View/download PDF
9. Factors that differentiate COVID-19 vaccine intentions among Indiana parents: Implications for targeted vaccine promotion
- Author
-
Head, Katharine J., Zimet, Gregory D., Yiannoutsos, Constantin T., Silverman, Ross D., Sanner, Lindsey, and Menachemi, Nir
- Published
- 2022
- Full Text
- View/download PDF
10. Research priorities to inform “Treat All” policy implementation for people living with HIV in sub‐Saharan Africa: a consensus statement from the International epidemiology Databases to Evaluate AIDS (IeDEA)
- Author
-
Yotebieng, Marcel, Brazier, Ellen, Addison, Diane, Kimmel, April D, Cornell, Morna, Keiser, Olivia, Parcesepe, Angela M, Onovo, Amobi, Lancaster, Kathryn E, Castelnuovo, Barbara, Murnane, Pamela M, Cohen, Craig R, Vreeman, Rachel C, Davies, Mary‐Ann, Duda, Stephany N, Yiannoutsos, Constantin T, Bono, Rose S, Agler, Robert, Bernard, Charlotte, Syvertsen, Jennifer L, Sinayobye, Jean d'Amour, Wikramanayake, Radhika, Sohn, Annette H, von Groote, Per M, Wandeler, Gilles, Leroy, Valeriane, Williams, Carolyn F, Wools‐Kaloustian, Kara, Nash, Denis, Althoff, Keri, Dominguez, Geraldina, Freeman, Aimee, Jaquet, Antoine, Markus, Janne, McKaig, Rosemary, Nsonde, Dominique, and Yiannoutsos, Constantin
- Subjects
Biomedical and Clinical Sciences ,Health Services and Systems ,Public Health ,Health Sciences ,Clinical Sciences ,HIV/AIDS ,Behavioral and Social Science ,Health Disparities ,Health Services ,Prevention ,Sexually Transmitted Infections ,Clinical Research ,Mental Health ,Infectious Diseases ,Infection ,Good Health and Well Being ,Africa South of the Sahara ,Databases ,Factual ,HIV Infections ,Health Policy ,Humans ,Policy Making ,Treat All ,universal HIV treatment ,90-90-90 targets ,sub-Saharan Africa ,implementation science ,IeDEA Treat All in sub-Saharan Africa Consensus Statement Working Group ,Public Health and Health Services ,Other Medical and Health Sciences ,Clinical sciences ,Epidemiology ,Public health - Abstract
Introduction"Treat All" - the treatment of all people with HIV, irrespective of disease stage or CD4 cell count - represents a paradigm shift in HIV care that has the potential to end AIDS as a public health threat. With accelerating implementation of Treat All in sub-Saharan Africa (SSA), there is a need for a focused agenda and research to identify and inform strategies for promoting timely uptake of HIV treatment, retention in care, and sustained viral suppression and addressing bottlenecks impeding implementation.MethodsThe Delphi approach was used to develop consensus around research priorities for Treat All implementation in SSA. Through an iterative process (June 2017 to March 2018), a set of research priorities was collectively formulated and refined by a technical working group and shared for review, deliberation and prioritization by more than 200 researchers, implementation experts, policy/decision-makers, and HIV community representatives in East, Central, Southern and West Africa.Results and discussionThe process resulted in a list of nine research priorities for generating evidence to guide Treat All policies, implementation strategies and monitoring efforts. These priorities highlight the need for increased focus on adolescents, men, and those with mental health and substance use disorders - groups that remain underserved in SSA and for whom more effective testing, linkage and care strategies need to be identified. The priorities also reflect consensus on the need to: (1) generate accurate national and sub-national estimates of the size of key populations and describe those who remain underserved along the HIV-care continuum; (2) characterize the timeliness of HIV care and short- and long-term HIV care continuum outcomes, as well as factors influencing timely achievement of these outcomes; (3) estimate the incidence and prevalence of HIV-drug resistance and regimen switching; and (4) identify cost-effective and affordable service delivery models and strategies to optimize uptake and minimize gaps, disparities, and losses along the HIV-care continuum, particularly among underserved populations.ConclusionsReflecting consensus among a broad group of experts, researchers, policy- and decision-makers, PLWH, and other stakeholders, the resulting research priorities highlight important evidence gaps that are relevant for ministries of health, funders, normative bodies and research networks.
- Published
- 2019
11. Virologic non-suppression and early loss to follow up among pregnant and non-pregnant adolescents aged 15-19 years initiating antiretroviral therapy in South Africa: a retrospective cohort study
- Author
-
Nyakato, Patience, Schomaker, Michael, Fatti, Geoffrey, Tanser, Frank, Euvrard, Jonathan, Sipambo, Nosisa, Fox, Matthew P., Haas, Andreas D., Yiannoutsos, Constantin T., Davies, Mary-Ann, and Cornell, Morna
- Subjects
Pregnant girls -- Drug therapy -- Statistics ,Highly active antiretroviral therapy -- Patient outcomes -- Statistics ,HIV infection -- Drug therapy -- Patient outcomes -- Statistics ,Health - Abstract
Introduction: Older adolescents aged 15-19 years continue to have high rates of loss to follow up (LTFU), and high rates of virologic non-suppression (VNS) compared to younger adolescents and adults. Adolescent females are at risk of pregnancy, which puts those living with HIV at a dualvulnerability. Our study assessed the factors associated with VNS and LTFU in older adolescents (including pregnant females) who initiated antiretroviral therapy (ART) in South Africa. Methods: We included adolescents aged 15-19 years initiating ART between 2004 and 2019, with [greater than or equal to] one viral load (VL) measurement between 4 and 24.5 months, and [greater than or equal to] 6 months follow-up, from six South African cohorts of the International epidemiology Databases to Evaluate AIDS-Southern Africa (IeDEA-SA). We defined VNS as VL [greater than or equal to]400 copies/ml and LTFU as not being in care for [greater than or equal to]180 days from ART start and not known as transferred out of the clinic or dead in the first 24 months on ART We examined factors associated with VNS and LTFU using Fine&Gray competing risk models. Results: We included a totalof 2733 adolescents, 415 (15.2%) males, median (IQR) age at ART start of 18.6 (17.3, 19.4) years. Among females, 585/2318 (25.2%) were pregnant. Over the 24-month follow-up, 424 (15.5%) of alladolescents experienced VNS: range (11.1% pregnant females and 20.5% males). Over half of all adolescents were LTFU before any other event could occur. The hazard of VNS reduced with increasing age and CD4 count above 200 cells/[micro]l at ART initiation among all adolescents having adjusted for allmeasured patient characteristics [adjusted sub-distribution hazard ratio (aSHR) 19 vs. 15 years: 0.50 (95% CI: 0.36, 0.68), aSHR: >500 vs. =200 cells/[micro]l: 0.22 (95% CI: 0.16, 0.31)]. The effect of CD4 count persisted in pregnant females. Increasing age and CD4 count >200 cells/[micro]l were risk factors for LTFU among alladolescents. Conclusions: Older adolescents had a high risk of LTFU shortly after ART start and a low risk of VNS, especially those initiating treatment during pregnancy. Interventions addressing adherence and retention should be incorporated into adolescent-friendly services to prevent VNS and LTFU and endeavour to trace lost adolescents as soon as they are identified. Keywords: adolescents; antiretroviraltherapy; HIV; loss to follow up; pregnancy; virologic non-suppression, 1 | INTRODUCTION In 2019, about 1.7 (1.1-2.4) million adolescents aged 10-19 years and 3.4 million youth aged 15-24 years were living with HIV worldwide [1], with the majority living [...]
- Published
- 2022
- Full Text
- View/download PDF
12. Bayesian estimation of SARS-CoV-2 prevalence in Indiana by random testing
- Author
-
Yiannoutsos, Constantin T., Halverson, Paul K., and Menachemi, Nir
- Published
- 2021
13. Population Point Prevalence of SARS-CoV-2 Infection Based on a Statewide Random Sample — Indiana, April 25–29, 2020
- Author
-
Menachemi, Nir, Yiannoutsos, Constantin T., Dixon, Brian E., Duszynski, Thomas J., Fadel, William F., Wools-Kaloustian, Kara K., Needleman, Nadia Unruh, Box, Kristina, Caine, Virginia, Norwood, Connor, Weaver, Lindsay, and Halverson, Paul K.
- Published
- 2020
14. Increased prevalence of pregnancy and comparative risk of program attrition among individuals starting HIV treatment in East Africa.
- Author
-
Holmes, Charles B, Yiannoutsos, Constantin T, Elul, Batya, Bukusi, Elizabeth, Ssali, John, Kambugu, Andrew, Musick, Beverly S, Cohen, Craig, Williams, Carolyn, Diero, Lameck, Padian, Nancy, and Wools-Kaloustian, Kara K
- Subjects
Humans ,Pregnancy Complications ,Infectious ,HIV Infections ,Anti-HIV Agents ,Prevalence ,Patient Compliance ,Pregnancy ,Adult ,Patient Dropouts ,Africa ,Eastern ,Female ,Young Adult ,General Science & Technology - Abstract
BackgroundThe World Health Organization now recommends initiating all pregnant women on life-long antiretroviral therapy (ART), yet there is limited information about the characteristics and program outcomes of pregnant women already on ART in Africa. Our hypothesis was that pregnant women comprised an increasing proportion of those starting ART, and that sub-groups of these women were at higher risk for program attrition.Methods and findingsWe used the International Epidemiology Databases to Evaluate AIDS- East Africa (IeDEA-EA) to conduct a retrospective cohort study including HIV care and treatment programs in Kenya, Uganda, and Tanzania. The cohort consecutively included HIV-infected individuals 13 years or older starting ART 2004-2014. We examined trends over time in the proportion pregnant, their characteristics and program attrition rates compared to others initiating and already receiving ART. 156,474 HIV-infected individuals (67.0% women) started ART. The proportion of individuals starting ART who were pregnant women rose from 5.3% in 2004 to 12.2% in 2014. Mean CD4 cell counts at ART initiation, weighted for annual program size, increased from 2004 to 2014, led by non-pregnant women (annual increase 20 cells/mm3) and men (17 cells/mm3 annually), with lower rates of change in pregnant women (10 cells/mm3 per year) (p
- Published
- 2018
15. Adherence to antiretroviral therapy in a clinical cohort of HIV-infected children in East Africa
- Author
-
Vreeman, Rachel C, Ayaya, Samuel O, Musick, Beverly S, Yiannoutsos, Constantin T, Cohen, Craig R, Nash, Denis, Wabwire, Deo, Wools-Kaloustian, Kara, and Wiehe, Sarah E
- Subjects
HIV/AIDS ,Pediatric ,Infectious Diseases ,Clinical Research ,6.1 Pharmaceuticals ,Management of diseases and conditions ,Evaluation of treatments and therapeutic interventions ,7.1 Individual care needs ,Infection ,Good Health and Well Being ,Adolescent ,Africa ,Eastern ,Anti-HIV Agents ,Child ,Child ,Preschool ,Female ,HIV Infections ,Humans ,Infant ,Male ,Patient Compliance ,General Science & Technology - Abstract
ObjectiveTo describe antiretroviral therapy (ART) adherence and associated factors for a large HIV-infected pediatric cohort followed by sites of the East Africa International Epidemiologic Databases to Evaluate AIDS (IeDEA) consortium.MethodsThis study utilized prospectively collected clinical data from HIV-infected children less than 13 years of age who initiated ART within 4 clinical care programs (with 26 clinical sites) in Kenya, Uganda, and Tanzania and were followed for up to 6 years. Programs used one of 3 adherence measures, including 7-day quantitative recall, 7-day categorical recall, and clinician pill assessments. We fit a hierarchical, three-level, logistic-regression model to examine adherence, with observations nested within patient, and patients within the 26 sites providing pediatric HIV data to this analysis.ResultsIn East Africa, 3,304 children, 52.0% male, were enrolled in care and were subsequently observed for a median of 92 weeks (inter-quartile range [IQR] 50.3-145.0 weeks). Median age at ART initiation was 5.5 years ([IQR] 3.0-8.5 years). "Good" adherence, as reported by each clinic's measures, was extremely high, remaining on average above 90% throughout all years of follow-up. Longer time on ART was associated with higher adherence (adjusted Odds Ratio-aOR-per log-transformed week on ART: 1.095, 95% Confidence Interval-CI-[1.052-1.150].) Patients enrolled in higher-volume programs exhibited higher rates of clinician-assessed adherence (aOR per log-500 patients: 1.174, 95% CI [1.108-1.245]). Significant site-level variability in reported adherence was observed (0.28), with even higher variability among patients (0.71). In a sub-analysis, being an orphan at the start of ART was strongly associated with lower ART adherence rates (aOR: 0.919, 95% CI [0.864-0.976]).ConclusionsSelf-reported adherence remained high over a median of 1.8 years in HIV care, but varied according to patient-level and site-level factors. Consistent adherence monitoring with validated measures and attention to vulnerable groups is recommended.
- Published
- 2018
16. Global HIV mortality trends among children on antiretroviral treatment corrected for under-reported deaths: an updated analysis of the International epidemiology Databases to Evaluate AIDS collaboration
- Author
-
Kassanjee, Reshma, Johnson, Leigh F., Zaniewski, Elizabeth, Ballif, Marie, Christ, Benedikt, Yiannoutsos, Constantin T., Nyakato, Patience, Desmonde, Sophie, Edmonds, Andrew, Sudjaritruk, Tavitiya, Pinto, Jorge, Vreeman, Rachel, Dahourou, Desire Lucien, Twizere, Christelle, Kariminia, Azar, Carlucci, James G., Kasozi, Charles, and Davies, Mary-Ann
- Subjects
World health -- Research ,HIV infection in children -- Patient outcomes -- Forecasts and trends -- Drug therapy ,Antiviral agents -- Usage -- Patient outcomes ,AIDS (Disease) -- Research ,AIDS research ,Pediatric research ,Children -- Death ,Market trend/market analysis ,Health - Abstract
Introduction: The Joint United Nations Programme on HIV/AIDS (UNAIDS) projections of paediatric HIV prevalence and deaths rely on the International epidemiology Databases to Evaluate AIDS (leDEA) consortium for mortality estimates among children living with HIV (CHIV) receiving antiretroviral therapy (ART). Previous estimates, based on data through 2014, may no longer be accurate due to expanded paediatric HIV care and treatment eligibility, and the possibility of unreported deaths in CHIV considered lost to follow-up (LTFU). We therefore estimated all-cause mortality and its trends in CHIV ( Methods: We analysed (i) leDEA observational data from CHIV in routine care globally, and (ii) novel data from an leDEA tracing study that determined outcomes in a sample of CHIV after being LTFU in southern Africa. We included 45,711 CHIV on ART during 2004 to 2017 at 72 programmes in Africa, Asia-Pacific and Latin America. We used mixed effects Poisson regression to estimate mortality by age, sex, CD4 at ART start, time on ART, region and calendar year. For Africa, in an adjusted analysis that accounts for unreported deaths among those LTFU, we first modified the routine data by simulating mortality outcomes within six months after LTFU, based on a Gompertz survival model fitted to the tracing data (n = 221). Results: Observed mortality rates were 1.8 (95% CI: 1.7 to 1.9) and 9.4 (6.3 to 13.4) deaths per 100 person-years in the routine and tracing data, respectively. We found strong evidence of higher mortality at shorter ART durations, lower CD4 values, and in infancy. Averaging over covariate patterns, the adjusted mortality rate was 54% higher than the unadjusted rate. In unadjusted analyses, mortality reduced by an average 60% and 73% from 2005 to 2017, within and outside of Africa, respectively. In the adjusted analysis for Africa, this temporal reduction was 42%. Conclusions: Mortality rates among CHIV have decreased substantially over time. However, when accounting for worse outcomes among those LTFU, mortality estimates increased and temporal improvements were slightly reduced, suggesting caution in interpreting analyses based only on programme data. The improved and updated leDEA estimates on mortality among CHIV on ART support UNAIDS efforts to accurately model global HIV statistics. Keywords: antiretroviral therapy; HIV; mortality; tracing; trends; under-ascertainment, 1 | INTRODUCTION Accurate estimates of the number of children living with HIV (CHIV) are essential for programme planning and resource allocation [1,2]. Further, the number of deaths among CHIV [...]
- Published
- 2021
- Full Text
- View/download PDF
17. Achieving consistency in measures of HIV-1 viral suppression across countries: derivation of an adjustment based on international antiretroviral treatment cohort data
- Author
-
Johnson, Leigh F., Kariminia, Azar, Trickey, Adam, Yiannoutsos, Constantin T., Ekouevi, Didier K., Minga, Albert K., Pascom, Ana Roberta Pati, Han, Win Min, Zhang, Lei, Althoff, Keri N., Rebeiro, Peter F., Murenzi, Gad, Ross, Jonathan, Hsiao, Nei-Yuan, and Marsh, Kimberly
- Subjects
Health - Abstract
Introduction: The third of the Joint United Nations Programme on HIV/AIDS (UNAIDS) 90-90-90 targets is to achieve a 90% rate of viral suppression (HIV viral load Methods: We considered three possible distributions for viral loads in ART patients: Weibull, Pareto and reverse Weibull (imposing an upper limit but no lower limit on the log scale). The models were fitted to data on viral load distributions in ART patients in the International epidemiology Databases to Evaluate AIDS (IeDEA) collaboration (representing seven global regions) and the ART Cohort Collaboration (representing Europe), using separate random effects models for adults and children. The models were validated using data from the World Health Organization (WHO) HIV drug resistance report and the Brazilian national ART programme. Results: Models were calibrated using 921,157 adult and 37,431 paediatric viral load measurements, over 2010-2019. The Pareto and reverse Weibull models provided the best fits to the data, but for all models, the 'shape' parameters for the viral load distributions differed significantly between regions. The Weibull model performed best in the validation against the WHO drug resistance survey data, while the Pareto model produced uncertainty ranges that were too narrow, relative to the validation data. Based on these analyses, we recommend using the reverse Weibull model. For example, if a country reports an 80% rate of viral suppression at Conclusions: Estimates of viral suppression can change substantially depending on the threshold used in defining viral suppression. It is, therefore, important that viral suppression rates are standardized to the same threshold for the purpose of assessing progress towards UNAIDS targets. We have proposed a simple adjustment that allows this, and this has been incorporated into UNAIDS modelling software. Keywords: antiretroviral therapy; HIV; viral load, 1 | INTRODUCTION Antiretroviral treatment (ART) is highly effective in preventing the replication of HIV, which is crucial to restoring the immune systems of people living with HIV [1], improving [...]
- Published
- 2021
- Full Text
- View/download PDF
18. Updating vital status by tracking in the community among patients with epidemic Kaposi sarcoma who are lost to follow-up in sub-Saharan Africa
- Author
-
Semeere, Aggrey, Freeman, Esther, Wenger, Megan, Glidden, David, Bwana, Mwebesa, Kanyesigye, Micheal, Asirwa, Fredrick Chite, Rotich, Elyne, Busakhala, Naftali, Oga, Emmanuel, Jedy-Agba, Elima, Kwaghe, Vivian, Iregbu, Kenneth, Adebamowo, Clement, Jaquet, Antoine, Dabis, Francois, Phiri, Sam, Bohlius, Julia, Egger, Matthias, Yiannoutsos, Constantin T, Wools-Kaloustian, Kara, and Martin, Jeffrey
- Subjects
Health Services and Systems ,Biomedical and Clinical Sciences ,Health Sciences ,Infectious Diseases ,Cancer ,HIV/AIDS ,Clinical Research ,Sexually Transmitted Infections ,Rare Diseases ,2.4 Surveillance and distribution ,Good Health and Well Being ,AIDS-Related Opportunistic Infections ,Adult ,Africa South of the Sahara ,Anti-HIV Agents ,Epidemics ,Female ,HIV Infections ,Humans ,Lost to Follow-Up ,Male ,Sarcoma ,Kaposi ,Loss to follow-up ,Tracking ,Tracing ,Updating vital status ,Survival ,Mortality ,Kaposi sarcoma ,Resource-limited settings ,Sub-Saharan Africa ,Oncology and Carcinogenesis ,Public Health and Health Services ,Oncology & Carcinogenesis ,Oncology and carcinogenesis ,Epidemiology - Abstract
BackgroundThroughout most of sub-Saharan Africa (and, indeed, most resource-limited areas), lack of death registries prohibits linkage of cancer diagnoses and precludes the most expeditious approach to determining cancer survival. Instead, estimation of cancer survival often uses clinical records, which have some mortality data but are replete with patients who are lost to follow-up (LTFU), some of which may be caused by undocumented death. The end result is that accurate estimation of cancer survival is rarely performed. A prominent example of a common cancer in Africa for which survival data are needed but for which frequent LTFU has precluded accurate estimation is Kaposi sarcoma (KS).MethodsUsing electronic records, we identified all newly diagnosed KS among HIV-infected adults at 33 primary care clinics in Kenya, Uganda, Nigeria, and Malawi from 2009 to 2012. We determined those patients who were apparently LTFU, defined as absent from clinic for ≥90 days at database closure and unknown to be dead or transferred. Using standardized protocols which included manual chart review, telephone calls, and physical tracking in the community, we attempted to update vital status amongst patients who were LTFU.ResultsWe identified 1222 patients with KS, of whom 440 were LTFU according to electronic records. Manual chart review revealed that 18 (4.1%) were classified as LFTU due to clerical error, leaving 422 as truly LTFU. Of these 422, we updated vital status in 78%; manual chart review was responsible for updating in 5.7%, telephone calls in 26%, and physical tracking in 46%. Among 378 patients who consented at clinic enrollment to be tracked if they became LTFU and who had sufficient geographic contact/locator information, we updated vital status in 88%. Duration of LTFU was not associated with success of tracking, but tracking success was better in Kenya than the other sites.ConclusionIt is feasible to update vital status in a large fraction of patients with HIV-associated KS in sub-Saharan Africa who have become LTFU from clinical care. This finding likely applies to other cancers as well. Updating vital status amongst lost patients paves the way towards accurate determination of cancer survival.
- Published
- 2017
19. Adaptation of the Client Diagnostic Questionnaire for East Africa
- Author
-
Kwobah, Edith Kamaru, primary, Goodrich, Suzanne, additional, Kulzer, Jayne Lewis, additional, Kanyesigye, Michael, additional, Obatsa, Sarah, additional, Cheruiyot, Julius, additional, Kiprono, Lorna, additional, Kibet, Colma, additional, Ochieng, Felix, additional, Bukusi, Elizabeth A., additional, Ofner, Susan, additional, Brown, Steven A., additional, Yiannoutsos, Constantin T., additional, Atwoli, Lukoye, additional, and Wools-Kaloustian, Kara, additional
- Published
- 2024
- Full Text
- View/download PDF
20. Mortality Among HIV-Infected Adults on Antiretroviral Therapy in Southern Uganda
- Author
-
Nabukalu, Dorean, primary, Yiannoutsos, Constantin T., additional, Semeere, Aggrey, additional, Musick, Beverly S., additional, Murungi, Teddy, additional, Namulindwa, Jane Viola, additional, Waswa, Francis, additional, Nakigozi, Gertrude, additional, Sewankambo, Nelson K., additional, Reynolds, Steven J., additional, Lutalo, Tom, additional, Makumbi, Fredrick, additional, Kigozi, Godfrey, additional, Nalugoda, Fred, additional, and Wools-Kaloustian, Kara, additional
- Published
- 2024
- Full Text
- View/download PDF
21. Evaluating the Impact of a HIV Low-Risk Express Care Task-Shifting Program: A Case Study of the Targeted Learning Roadmap
- Author
-
Tran, Linh, Yiannoutsos, Constantin T, Musick, Beverly S, Wools-Kaloustian, Kara K, Siika, Abraham, Kimaiyo, Sylvester, van der Laan, Mark J, and Petersen, Maya
- Subjects
Economics ,Applied Economics ,Health Sciences ,Clinical Research ,Infection ,causal estimation ,causal inference ,causal road map ,semiparametric models ,targeted learning - Abstract
In conducting studies on an exposure of interest, a systematic roadmap should be applied for translating causal questions into statistical analyses and interpreting the results. In this paper we describe an application of one such roadmap applied to estimating the joint effect of both time to availability of a nurse-based triage system (low risk express care (LREC)) and individual enrollment in the program among HIV patients in East Africa. Our study population is comprised of 16,513 subjects found eligible for this task-shifting program within 15 clinics in Kenya between 2006 and 2009, with each clinic starting the LREC program between 2007 and 2008. After discretizing follow-up into 90-day time intervals, we targeted the population mean counterfactual outcome (i. e. counterfactual probability of either dying or being lost to follow up) at up to 450 days after initial LREC eligibility under three fixed treatment interventions. These were (i) under no program availability during the entire follow-up, (ii) under immediate program availability at initial eligibility, but non-enrollment during the entire follow-up, and (iii) under immediate program availability and enrollment at initial eligibility. We further estimated the controlled direct effect of immediate program availability compared to no program availability, under a hypothetical intervention to prevent individual enrollment in the program. Targeted minimum loss-based estimation was used to estimate the mean outcome, while Super Learning was implemented to estimate the required nuisance parameters. Analyses were conducted with the ltmle R package; analysis code is available at an online repository as an R package. Results showed that at 450 days, the probability of in-care survival for subjects with immediate availability and enrollment was 0.93 (95% CI: 0.91, 0.95) and 0.87 (95% CI: 0.86, 0.87) for subjects with immediate availability never enrolling. For subjects without LREC availability, it was 0.91 (95% CI: 0.90, 0.92). Immediate program availability without individual enrollment, compared to no program availability, was estimated to slightly albeit significantly decrease survival by 4% (95% CI 0.03,0.06, p
- Published
- 2016
22. Facility-Level Factors Influencing Retention of Patients in HIV Care in East Africa
- Author
-
Rachlis, Beth, Bakoyannis, Giorgos, Easterbrook, Philippa, Genberg, Becky, Braithwaite, Ronald Scott, Cohen, Craig R, Bukusi, Elizabeth A, Kambugu, Andrew, Bwana, Mwebesa Bosco, Somi, Geoffrey R, Geng, Elvin H, Musick, Beverly, Yiannoutsos, Constantin T, Wools-Kaloustian, Kara, and Braitstein, Paula
- Subjects
Biomedical and Clinical Sciences ,Public Health ,Health Sciences ,Sexually Transmitted Infections ,HIV/AIDS ,Emerging Infectious Diseases ,Clinical Research ,Infectious Diseases ,7.1 Individual care needs ,Infection ,Good Health and Well Being ,Adult ,Anti-HIV Agents ,CD4 Lymphocyte Count ,Databases ,Factual ,Delivery of Health Care ,Female ,HIV ,HIV Infections ,Health Facilities ,Humans ,Kaplan-Meier Estimate ,Kenya ,Lost to Follow-Up ,Male ,Proportional Hazards Models ,RNA ,Viral ,Reverse Transcriptase Polymerase Chain Reaction ,Tanzania ,Uganda ,General Science & Technology - Abstract
Losses to follow-up (LTFU) remain an important programmatic challenge. While numerous patient-level factors have been associated with LTFU, less is known about facility-level factors. Data from the East African International epidemiologic Databases to Evaluate AIDS (EA-IeDEA) Consortium was used to identify facility-level factors associated with LTFU in Kenya, Tanzania and Uganda. Patients were defined as LTFU if they had no visit within 12 months of the study endpoint for pre-ART patients or 6 months for patients on ART. Adjusting for patient factors, shared frailty proportional hazard models were used to identify the facility-level factors associated with LTFU for the pre- and post-ART periods. Data from 77,362 patients and 29 facilities were analyzed. Median age at enrolment was 36.0 years (Interquartile Range: 30.1, 43.1), 63.9% were women and 58.3% initiated ART. Rates (95% Confidence Interval) of LTFU were 25.1 (24.7-25.6) and 16.7 (16.3-17.2) per 100 person-years in the pre-ART and post-ART periods, respectively. Facility-level factors associated with increased LTFU included secondary-level care, HIV RNA PCR turnaround time >14 days, and no onsite availability of CD4 testing. Increased LTFU was also observed when no nutritional supplements were provided (pre-ART only), when TB patients were treated within the HIV program (pre-ART only), and when the facility was open ≤4 mornings per week (ART only). Our findings suggest that facility-based strategies such as point of care laboratory testing and separate clinic spaces for TB patients may improve retention.
- Published
- 2016
23. Estimation of mortality among HIV-infected people on antiretroviral treatment in east Africa: a sampling based approach in an observational, multisite, cohort study
- Author
-
Geng, Elvin H, Odeny, Thomas A, Lyamuya, Rita E, Nakiwogga-Muwanga, Alice, Diero, Lameck, Bwana, Mwebesa, Muyindike, Winnie, Braitstein, Paula, Somi, Geoffrey R, Kambugu, Andrew, Bukusi, Elizabeth A, Wenger, Megan, Wools-Kaloustian, Kara K, Glidden, David V, Yiannoutsos, Constantin T, and Martin, Jeffrey N
- Subjects
Public Health ,Biomedical and Clinical Sciences ,Clinical Sciences ,Health Sciences ,Infectious Diseases ,Sexually Transmitted Infections ,Clinical Research ,HIV/AIDS ,Infection ,Good Health and Well Being ,Adult ,Anti-HIV Agents ,Antiretroviral Therapy ,Highly Active ,CD4 Lymphocyte Count ,Cohort Studies ,Data Collection ,Female ,HIV Infections ,Humans ,Kenya ,Male ,Sampling Studies ,Tanzania ,Uganda ,United States ,Young Adult ,Medical and Health Sciences ,Biomedical and clinical sciences ,Health sciences - Abstract
BackgroundMortality in HIV-infected people after initiation of antiretroviral treatment (ART) in resource-limited settings is an important measure of the effectiveness and comparative effectiveness of the global public health response. Substantial loss to follow-up precludes accurate accounting of deaths and limits our understanding of effectiveness. We aimed to provide a better understanding of mortality at scale and, by extension, the effectiveness and comparative effectiveness of public health ART treatment in east Africa.MethodsIn 14 clinics in five settings in Kenya, Uganda, and Tanzania, we intensively traced a sample of patients randomly selected using a random number generator, who were infected with HIV and on ART and who were lost to follow-up (>90 days late for last scheduled visit). We incorporated the vital status outcomes for these patients into analyses of the entire clinic population through probability-weighted survival analyses.FindingsWe followed 34 277 adults on ART from Mbarara and Kampala in Uganda, Eldoret, and Kisumu in Kenya, and Morogoro in Tanzania. The median age was 35 years (IQR 30-42), 11 628 (34%) were men, and median CD4 count count before therapy was 154 cells per μL (IQR 70-234). 5780 patients (17%) were lost to follow-up, 991 (17%) were selected for tracing between June 10, 2011, and Aug 27, 2012, and vital status was ascertained for 860 (87%). With incorporation of outcomes from the patients lost to follow-up, estimated 3 year mortality increased from 3·9% (95% CI 3·6-4·2) to 12·5% (11·8-13·3). The sample-corrected, unadjusted 3 year mortality across settings was lowest in Mbarara (7·2%) and highest in Morogoro (23·6%). After adjustment for age, sex, CD4 count before therapy, and WHO stage, the sample-corrected hazard ratio comparing the settings with highest and lowest mortalities was 2·2 (95% CI 1·5-3·4) and the risk difference for death at 3 years was 11% (95% CI 5·0-17·7).InterpretationA sampling-based approach is widely feasible and important to an understanding of mortality after initiation of ART. After adjustment for measured biological drivers, mortality differs substantially across settings despite delivery of a similar clinical package of treatment. Implementation research to understand the systems, community, and patients' behaviours driving these differences is urgently needed.FundingThe US National Institutes of Health and President's Emergency Fund for AIDS Relief.
- Published
- 2015
24. Semiparametric competing risks regression under interval censoring using the R package intccr
- Author
-
Park, Jun, Bakoyannis, Giorgos, and Yiannoutsos, Constantin T.
- Published
- 2019
- Full Text
- View/download PDF
25. CD4+ T cell recovery during suppression of HIV replication: an international comparison of the immunological efficacy of antiretroviral therapy in North America, Asia and Africa
- Author
-
Geng, Elvin H, Neilands, Torsten B, Thièbaut, Rodolphe, Bwana, Mwebesa Bosco, Nash, Denis, Moore, Richard D, Wood, Robin, Zannou, Djimon Marcel, Althoff, Keri N, Lim, Poh Lian, Nachega, Jean B, Easterbrook, Philippa J, Kambugu, Andrew, Little, Francesca, Nakigozi, Gertrude, Nakanjako, Damalie, Kiggundu, Valerian, Li, Patrick Chung Ki, Bangsberg, David R, Fox, Matthew P, Prozesky, Hans W, Hunt, Peter W, Davies, Mary-Ann, Reynolds, Steven J, Egger, Matthias, Yiannoutsos, Constantin T, Vittinghoff, Eric V, Deeks, Steven G, and Martin, Jeffrey N
- Subjects
Epidemiology ,Public Health ,Health Sciences ,Statistics ,Mathematical Sciences ,Sexually Transmitted Infections ,HIV/AIDS ,Genetics ,Infectious Diseases ,6.1 Pharmaceuticals ,Infection ,Good Health and Well Being ,Adult ,Africa ,Alkynes ,Anti-HIV Agents ,Asia ,Benzoxazines ,CD4 Lymphocyte Count ,Cyclopropanes ,Drug Therapy ,Combination ,Female ,HIV Infections ,Humans ,Male ,Nevirapine ,North America ,RNA ,Viral ,Virus Replication ,HIV ,antiretroviral therapy ,CD4+T cell counts ,immunological activation ,Public Health and Health Services ,Public health - Abstract
Background: Even among HIV-infected patients who fully suppress plasma HIV RNA replication on antiretroviral therapy, genetic (e.g. CCL3L1 copy number), viral (e.g. tropism) and environmental (e.g. chronic exposure to microbial antigens) factors influence CD4 recovery. These factors differ markedly around the world and therefore the expected CD4 recovery during HIV RNA suppression may differ globally. Methods: We evaluated HIV-infected adults from North America, West Africa, East Africa, Southern Africa and Asia starting non-nucleoside reverse transcriptase inhibitorbased regimens containing efavirenz or nevirapine, who achieved at least one HIV RNA level < 500/μl in the first year of therapy and observed CD4 changes during HIV RNA suppression. We used a piecewise linear regression to estimate the influence of region of residence on CD4 recovery, adjusting for socio-demographic and clinical characteristics. We observed 28 217 patients from 105 cohorts over 37 825 person-years. Results: After adjustment, patients from East Africa showed diminished CD4 recovery as compared with other regions. Three years after antiretroviral therapy initiation, the mean CD4 count for a prototypical patient with a pre-therapy CD4 count of 150/μl was 529/μl [95% confidence interval (CI): 517-541] in North America, 494/μl (95% CI: 429-559) in West Africa, 515/μl (95% CI: 508-522) in Southern Africa, 503/μl (95% CI: 478-528) in Asia and 437/μl (95% CI: 425-449) in East Africa. Conclusions: CD4 recovery during HIV RNA suppression is diminished in East Africa as compared with other regions of the world, and observed differences are large enough to potentially influence clinical outcomes. Epidemiological analyses on a global scale can identify macroscopic effects unobservable at the clinical, national or individual regional level.
- Published
- 2015
26. NONPARAMETRIC INFERENCE FOR MARKOV PROCESSES WITH MISSING ABSORBING STATE
- Author
-
Bakoyannis, Giorgos, Zhang, Ying, and Yiannoutsos, Constantin T.
- Published
- 2019
27. Cerebral metabolite changes prior to and after antiretroviral therapy in primary HIV infection.
- Author
-
Young, Andrew C, Yiannoutsos, Constantin T, Hegde, Manu, Lee, Evelyn, Peterson, Julia, Walter, Rudy, Price, Richard W, Meyerhoff, Dieter J, and Spudich, Serena
- Subjects
Humans ,HIV Infections ,Chronic Disease ,Anti-Retroviral Agents ,Magnetic Resonance Spectroscopy ,Longitudinal Studies ,Adult ,Middle Aged ,Female ,Male ,Cerebrum ,Neurosciences ,Infectious Diseases ,Behavioral and Social Science ,HIV/AIDS ,Clinical Research ,Clinical Sciences ,Cognitive Sciences ,Neurology & Neurosurgery - Abstract
ObjectiveWe examined the longitudinal effects of primary HIV infection (PHI) and responses to early antiretroviral therapy (ART) on the brain using high-field magnetic resonance spectroscopy (MRS).MethodsCerebral metabolites were measured longitudinally with 4T proton MRS and assessed for ART effects in participants with PHI. Levels of glutamate (Glu), N-acetylaspartate (NAA), myo-inositol (MI), and choline-containing metabolites (Cho) were measured relative to creatine + phosphocreatine (Cr) in anterior cingulate, basal ganglia, frontal white matter, and parietal gray matter.ResultsFifty-three participants recruited at median 3.7 months post HIV transmission were followed a median 6.0 months. A total of 23 participants initiated ART during follow-up. Prior to ART, increases per month were observed in Cho/Cr (slope = 0.0012, p = 0.005) and MI/Cr (slope = 0.0041, p = 0.005) in frontal white matter as well as increases in MI/Cr (slope = 0.0041, p < 0.001) and NAA/Cr (slope = 0.0024, p = 0.030) in parietal gray matter. After initiation of ART, prior positive slopes were no longer significantly different from zero, while Glu/Cr in basal ganglia decreased (slope = -0.0038, p = 0.031).ConclusionsEarly in HIV infection, increases of Cho/Cr and MI/Cr in treatment-naive participants suggest progressive inflammation and gliosis in the frontal white matter and parietal gray matter, which is attenuated after initiation of ART. Elevated baseline Glu/Cr in basal ganglia may signal excitotoxicity; its subsequent stabilization and downward trajectory with ART may lend further support for early ART initiation.
- Published
- 2014
28. Delayed switch of antiretroviral therapy after virologic failure associated with elevated mortality among HIV-infected adults in Africa
- Author
-
Petersen, Maya L, Tran, Linh, Geng, Elvin H, Reynolds, Steven J, Kambugu, Andrew, Wood, Robin, Bangsberg, David R, Yiannoutsos, Constantin T, Deeks, Steven G, and Martin, Jeffrey N
- Subjects
Medical Microbiology ,Biomedical and Clinical Sciences ,HIV/AIDS ,Infectious Diseases ,Clinical Research ,Sexually Transmitted Infections ,6.1 Pharmaceuticals ,Infection ,Good Health and Well Being ,Anti-HIV Agents ,Antiretroviral Therapy ,Highly Active ,CD4-Positive T-Lymphocytes ,Cohort Studies ,Drug Administration Schedule ,HIV Infections ,Humans ,Prospective Studies ,RNA ,Viral ,South Africa ,Time Factors ,Treatment Failure ,Uganda ,Viral Load ,antiretroviral ,cohort studies ,HIV ,HIV RNA level ,inverse probability weight ,marginal structural model ,time-dependent confounding ,treatment failure ,viral load ,Biological Sciences ,Medical and Health Sciences ,Psychology and Cognitive Sciences ,Virology ,Biomedical and clinical sciences ,Health sciences - Abstract
ObjectiveRoutine monitoring of plasma HIV RNA among HIV-infected patients on antiretroviral therapy (ART) is unavailable in many resource-limited settings. Alternative monitoring approaches correlate poorly with virologic failure and can substantially delay switch to second-line therapy. We evaluated the impact of delayed switch on mortality among patients with virologic failure in Africa.DesignA cohort.MethodsWe examined patients with confirmed virologic failure on first-line nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens from four cohorts with serial HIV RNA monitoring in Uganda and South Africa. Marginal structural models aimed to estimate the effect of delayed switch on mortality in a hypothetical trial in which switch time was randomly assigned. Inverse probability weights adjusted for measured confounders including time-updated CD4+ T-cell count and HIV RNA. Results: Among 823 patients with confirmed virologic failure, the cumulative incidence of switch 180 days after failure was 30% [95% confidence interval (CI) 27-33]. The majority of patients (74%) had not failed immunologically as defined by WHO criteria by the time of virologic failure. Adjusted mortality was higher for individuals who remained on first-line therapy than for those who had switched [odds ratio (OR) 2.1, 95% CI 1.1-4.2]. Among those without immunologic failure, the relative harm of failure to switch was similar (OR 2.4; 95% CI 0.99-5.8) to that of the entire cohort, although of borderline statistical significance.ConclusionAmong HIV-infected patients with confirmed virologic failure on first-line ART, remaining on first-line therapy led to an increase in mortality relative to switching. Our results suggest that detection and response to confirmed virologic failure could decrease mortality.
- Published
- 2014
29. Observational Research on NCDs in HIV-Positive Populations
- Author
-
Petersen, Maya, Yiannoutsos, Constantin T, Justice, Amy, and Egger, Matthias
- Subjects
Biomedical and Clinical Sciences ,Public Health ,Health Sciences ,Clinical Sciences ,Infectious Diseases ,Clinical Trials and Supportive Activities ,Prevention ,HIV/AIDS ,Clinical Research ,Generic health relevance ,Infection ,Good Health and Well Being ,Africa South of the Sahara ,Anti-Retroviral Agents ,Biomedical Research ,Comorbidity ,Delivery of Health Care ,Integrated ,Developing Countries ,Diagnostic Tests ,Routine ,HIV Infections ,Humans ,Prevalence ,Preventive Health Services ,Risk Factors ,Public Health and Health Services ,Virology ,Clinical sciences ,Epidemiology ,Public health - Abstract
Noncommunicable diseases (NCDs) account for a growing burden of morbidity and mortality among people living with HIV in low- and middle-income countries (LMICs). HIV infection and antiretroviral therapy interact with NCD risk factors in complex ways, and research into this "web of causation" has so far been largely based on data from high-income countries. However, improving the understanding, treatment, and prevention of NCDs in LMICs requires region-specific evidence. Priority research areas include: (1) defining the burden of NCDs among people living with HIV, (2) understanding the impact of modifiable risk factors, (3) evaluating effective and efficient care strategies at individual and health systems levels, and (4) evaluating cost-effective prevention strategies. Meeting these needs will require observational data, both to inform the design of randomized trials and to replace trials that would be unethical or infeasible. Focusing on Sub-Saharan Africa, we discuss data resources currently available to inform this effort and consider key limitations and methodological challenges. Existing data resources often lack population-based samples; HIV-negative, HIV-positive, and antiretroviral therapy-naive comparison groups; and measurements of key NCD risk factors and outcomes. Other challenges include loss to follow-up, competing risk of death, incomplete outcome ascertainment and measurement of factors affecting clinical decision making, and the need to control for (time-dependent) confounding. We review these challenges and discuss strategies for overcoming them through augmented data collection and appropriate analysis. We conclude with recommendations to improve the quality of data and analyses available to inform the response to HIV and NCD comorbidity in LMICs.
- Published
- 2014
30. Longitudinal characterization of depression and mood states beginning in primary HIV infection.
- Author
-
Gold, Jessica A, Grill, Marie, Peterson, Julia, Pilcher, Christopher, Lee, Evelyn, Hecht, Frederick M, Fuchs, Dietmar, Yiannoutsos, Constantin T, Price, Richard W, Robertson, Kevin, and Spudich, Serena
- Subjects
Humans ,HIV Infections ,Antidepressive Agents ,Anti-HIV Agents ,Longitudinal Studies ,Follow-Up Studies ,Prospective Studies ,Adaptation ,Psychological ,Depression ,Affect ,Psychiatric Status Rating Scales ,Neuropsychological Tests ,Personality Inventory ,Adult ,California ,Male ,Medication Adherence ,Acute/primary infection ,HIV ,Mood states ,Neuropsychological testing ,Adaptation ,Psychological ,Infectious Diseases ,Brain Disorders ,Neurosciences ,Behavioral and Social Science ,Mental Health ,Clinical Research ,HIV/AIDS ,6.1 Pharmaceuticals ,Infection ,Public Health ,Public Health and Health Services ,Social Work - Abstract
Though depression is known to frequently afflict those with chronic HIV, mood during the early course of HIV is not well characterized. In a prospective study we assessed mood during primary HIV infection [primary HIV infection (PHI),
- Published
- 2014
31. Correcting mortality estimates among children and youth on antiretroviral therapy in southern Africa: A comparative analysis between a multi‐country tracing study and linkage to a health information exchange.
- Author
-
Nyakato, Patience, Schomaker, Michael, Boulle, Andrew, Euvrard, Jonathan, Wood, Robin, Eley, Brian, Prozesky, Hans, Christ, Benedikt, Anderegg, Nanina, Ayakaka, Irene, Rafael, Idiovino, Kunzekwenyika, Cordelia, Moore, Carolyn B., van Lettow, Monique, Chimbetete, Cleophas, Mbewe, Safari, Ballif, Marie, Egger, Matthias, Yiannoutsos, Constantin T., and Cornell, Morna
- Abstract
Objectives: The objective of this study is to assess the outcomes of children, adolescents and young adults with HIV reported as lost to follow‐up, correct mortality estimates for children, adolescents and young adults with HIV for unascertained outcomes in those loss to follow‐up (LTFU) based on tracing and linkage data separately using data from the International epidemiology Databases to Evaluate AIDS in Southern Africa. Methods: We included data from two different populations of children, adolescents and young adults with HIV; (1) clinical data from children, adolescents and young adults with HIV aged ≤24 years from Lesotho, Malawi, Mozambique, Zambia and Zimbabwe; (2) clinical data from children, adolescents and young adults with HIV aged ≤14 years from the Western Cape (WC) in South Africa. Outcomes of patients lost to follow‐up were available from (1) a tracing study and (2) linkage to a health information exchange. For both populations, we compared six methods for correcting mortality estimates for all children, adolescents and young adults with HIV. Results: We found substantial variations of mortality estimates among children, adolescents and young adults with HIV reported as lost to follow‐up versus those retained in care. Ascertained mortality was higher among lost and traceable children, adolescents and young adults with HIV and lower among lost and linkable than those retained in care (mortality: 13.4% [traced] vs. 12.6% [retained‐other Southern Africa countries]; 3.4% [linked] vs. 9.4% [retained‐WC]). A high proportion of lost to follow‐up children, adolescents and young adults with HIV had self‐transferred (21.0% and 47.0%) in the traced and linked samples, respectively. The uncorrected method of non‐informative censoring yielded the lowest mortality estimates among all methods for both tracing (6.0%) and linkage (4.0%) approaches at 2 years from ART start. Among corrected methods using ascertained data, multiple imputation, incorporating ascertained data (MI(asc.)) and inverse probability weighting with logistic weights were most robust for the tracing approach. In contrast, for the linkage approach, MI(asc.) was the most robust. Conclusions: Our findings emphasise that lost to follow‐up is non‐ignorable and both tracing and linkage improved outcome ascertainment: tracing identified substantial mortality in those reported as lost to follow‐up, whereas linkage did not identify out‐of‐facility deaths, but showed that a large proportion of those reported as lost to follow‐up were self‐transfers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Modeling the HIV Cascade of Care Using Routinely Collected Clinical Data to Guide Programmatic Interventions and Policy Decisions.
- Author
-
Bakoyannis, Giorgos, Elul, Batya, Wools-Kaloustian, Kara K., Brown, Steven, Semeere, Aggrey, Castelnuovo, Barbara, Diero, Lameck, Nakigozi, Gertrude, Lyamuya, Rita, and Yiannoutsos, Constantin T.
- Published
- 2024
- Full Text
- View/download PDF
33. Preswitch Regimens Influence the Rate of Weight Gain After Switch to Tenofovir Disoproxil Fumarate, Lamivudine, and Dolutegravir (TLD): Study From an East African Cohort
- Author
-
Bourgi, Kassem, primary, Ofner, Susan, additional, Musick, Beverly, additional, Wools-Kaloustian, Kara, additional, Humphrey, John M, additional, Diero, Lameck, additional, Yiannoutsos, Constantin T, additional, and Gupta, Samir K, additional
- Published
- 2023
- Full Text
- View/download PDF
34. Diagnostic and Prognostic Value of JC Virus DNA in Plasma in Progressive Multifocal Leukoencephalopathy
- Author
-
Ferretti, Francesca, Bestetti, Arabella, Yiannoutsos, Constantin T., Musick, Beverly S., Gerevini, Simonetta, Passeri, Laura, Bossolasco, Simona, Boschini, Antonio, Franciotta, Diego, Lazzarin, Adriano, and Paola, Cinque
- Published
- 2018
35. Virologic response of adolescents living with perinatally acquired HIV receiving antiretroviral therapy in the period of early adolescence (10–14 years) in South Africa
- Author
-
Nyakato, Patience, Schomaker, Michael, Sipambo, Nosisa, Technau, Karl-Günter, Fatti, Geoffrey, Rabie, Helena, Tanser, Frank, Eley, Brian, Euvrard, Jonathan, Wood, Robin, Tsondai, Priscilla R., Yiannoutsos, Constantin T., Cornell, Morna, and Davies, Mary-Ann
- Published
- 2021
- Full Text
- View/download PDF
36. Cerebrospinal Fluid (CSF) Neuronal Biomarkers across the Spectrum of HIV Infection: Hierarchy of Injury and Detection
- Author
-
Peterson, Julia, Gisslen, Magnus, Zetterberg, Henrik, Fuchs, Dietmar, Shacklett, Barbara L, Hagberg, Lars, Yiannoutsos, Constantin T, Spudich, Serena S, and Price, Richard W
- Subjects
Medical Microbiology ,Biomedical and Clinical Sciences ,Immunology ,Neurosciences ,Infectious Diseases ,Neurodegenerative ,Alzheimer's Disease including Alzheimer's Disease Related Dementias (AD/ADRD) ,Acquired Cognitive Impairment ,Dementia ,Prevention ,Alzheimer's Disease ,Sexually Transmitted Infections ,HIV/AIDS ,Brain Disorders ,Clinical Research ,Aging ,2.1 Biological and endogenous factors ,4.1 Discovery and preclinical testing of markers and technologies ,Neurological ,Infection ,Adult ,Alzheimer Disease ,Amyloid beta-Peptides ,Amyloid beta-Protein Precursor ,Biomarkers ,Cross-Sectional Studies ,Female ,HIV ,HIV Infections ,Humans ,Male ,Middle Aged ,Nervous System Diseases ,Neurofilament Proteins ,Peptide Fragments ,Phosphorylation ,tau Proteins ,General Science & Technology - Abstract
The character of central nervous system (CNS) HIV infection and its effects on neuronal integrity vary with evolving systemic infection. Using a cross-sectional design and archived samples, we compared concentrations of cerebrospinal fluid (CSF) neuronal biomarkers in 143 samples from 8 HIV-infected subject groups representing a spectrum of untreated systemic HIV progression and viral suppression: primary infection; four groups of chronic HIV infection neuroasymptomatic (NA) subjects defined by blood CD4+ T cells of >350, 200-349, 50-199, and
- Published
- 2014
37. Failure to Initiate Antiretroviral Therapy, Loss to Follow-up and Mortality Among HIV-Infected Patients During the Pre-ART Period in Uganda
- Author
-
Geng, Elvin H, Bwana, Mwebesa B, Muyindike, Winnie, Glidden, David V, Bangsberg, David R, Neilands, Torsten B, Bernheimer, Ingrid, Musinguzi, Nicolas, Yiannoutsos, Constantin T, and Martin, Jeffrey N
- Subjects
Biomedical and Clinical Sciences ,Public Health ,Health Sciences ,Clinical Sciences ,HIV/AIDS ,Infectious Diseases ,Sexually Transmitted Infections ,Clinical Research ,Infection ,Good Health and Well Being ,Adult ,Anti-HIV Agents ,CD4 Lymphocyte Count ,CD4-Positive T-Lymphocytes ,Delivery of Health Care ,Educational Status ,HIV Infections ,Humans ,Lost to Follow-Up ,Male ,Medication Adherence ,Treatment Refusal ,Uganda ,antiretroviral therapy ,Africa ,loss to follow-up ,mortality ,Public Health and Health Services ,Virology ,Clinical sciences ,Epidemiology ,Public health - Abstract
BackgroundDelays and failures in initiation of antiretroviral therapy (ART) among treatment eligible patients may compromise the effectiveness of HIV care in Africa. An accurate understanding, however, of the pace and completeness of ART initiation and mortality during the waiting period is obscured by frequent losses to follow-up.MethodsWe evaluated newly ART-eligible HIV-infected adults from 2007 to 2011 in a prototypical clinic in Mbarara, Uganda. A random sample of patients lost to follow-up was tracked in the community to determine vital status and ART initiation after leaving the original clinic. Outcomes among the tracked patients were incorporated using probability weights, and a competing risks approach was used in analyses.ResultsAmong 2633 ART-eligible patients, 490 were lost to follow-up, of whom a random sample of 132 was tracked and 111 (84.0%) had outcomes ascertained. After incorporating the outcomes among the lost, the cumulative incidence of ART initiation at 30, 90, and 365 days after eligibility was 16.0% [95% confidence interval (CI): 14.2 to 17.7], 64.5% (95% CI: 60.9 to 68.1), and 81.7% (95% CI: 77.7 to 85.6). Death before ART was 7.7% at 1 year. Male sex, higher CD4 count, and no education were associated with delayed ART initiation. Lower CD4 level, malnourishment, and travel time to clinic were associated with mortality.ConclusionsUsing a sampling-based approach to account for losses to follow-up revealed that both the speed and the completeness of ART initiation were suboptimal in a prototypical large clinic in Uganda. Improving the kinetics of ART initiation in Africa is needed to make ART more in real-world populations.
- Published
- 2013
38. Cerebrospinal fluid neopterin decay characteristics after initiation of antiretroviral therapy
- Author
-
Yilmaz, Aylin, Yiannoutsos, Constantin T, Fuchs, Dietmar, Price, Richard W, Crozier, Kathryn, Hagberg, Lars, Spudich, Serena, and Gisslén, Magnus
- Abstract
Abstract Background Neopterin, a biomarker of macrophage activation, is elevated in the cerebrospinal fluid (CSF) of most HIV-infected individuals and decreases after initiation of antiretroviral therapy (ART). We studied decay characteristics of neopterin in CSF and blood after commencement of ART in HIV-infected subjects and estimated the set-point levels of CSF neopterin after ART-mediated viral suppression. Methods CSF and blood neopterin were longitudinally measured in 102 neurologically asymptomatic HIV-infected subjects who were treatment-naïve or had been off ART for ≥ 6 months. We used a non-linear model to estimate neopterin decay in response to ART and a stable neopterin set-point attained after prolonged ART. Seven subjects with HIV-associated dementia (HAD) who initiated ART were studied for comparison. Results Non-HAD patients were followed for a median 84.7 months. Though CSF neopterin concentrations decreased rapidly after ART initiation, it was estimated that set-point levels would be below normal CSF neopterin levels (
- Published
- 2013
39. Neurovirological Correlation With HIV-Associated Neurocognitive Disorders and Encephalitis in a HAART-Era Cohort
- Author
-
Gelman, Benjamin B, Lisinicchia, Joshua G, Morgello, Susan, Masliah, Eliezer, Commins, Deborah, Achim, Cristian L, Fox, Howard S, Kolson, Dennis L, Grant, Igor, Singer, Elyse, Yiannoutsos, Constantin T, Sherman, Seth, Gensler, Gary, Moore, David J, Chen, Tiansheng, and Soukup, Vicki M
- Subjects
Medical Microbiology ,Biomedical and Clinical Sciences ,Infectious Diseases ,Mental Health ,Neurodegenerative ,Genetics ,Brain Disorders ,Acquired Cognitive Impairment ,HIV/AIDS ,Neurosciences ,Sexually Transmitted Infections ,Infection ,AIDS Dementia Complex ,Adult ,Antiretroviral Therapy ,Highly Active ,Brain ,Cognition Disorders ,Cohort Studies ,DNA ,Viral ,Encephalitis ,Female ,HIV-1 ,Human Immunodeficiency Virus Proteins ,Humans ,Male ,Middle Aged ,Neuropsychological Tests ,RNA ,Viral ,Reverse Transcriptase Polymerase Chain Reaction ,Statistics ,Nonparametric ,dementia ,encephalitis ,HIVE ,neurocognitive disorders ,HAND ,interferon ,Clinical Sciences ,Public Health and Health Services ,Virology ,Clinical sciences ,Epidemiology ,Public health - Abstract
ObjectiveReplicating HIV-1 in the brain is present in HIV encephalitis (HIVE) and microglial nodule encephalitis (MGNE) and is putatively linked with HIV-associated neurocognitive disorders (HAND). A cliniconeurovirological correlation was conducted to elucidate the relationship between brain viral load and clinical phenotype. SUBJECTS AND ASSAYS: HIV gag/pol RNA and DNA copies were quantified with reverse transcriptase-polymerase chain reaction or polymerase chain reaction in 148 HAART-era brain specimens. Comparison with HAND, HIVE, and MGNE and correlation with neuropsychological (NP) test scores were done using one-way ANOVA with Tukey-Kramer and Spearman tests, respectively.ResultsBrain HIV RNA was higher in subjects with HAND plus HIVE versus without HAND (delta = 2.48 log10 units, n = 27 versus 36, P < 0.001). In HAND without HIVE or MGNE, brain HIV RNA was not significantly different versus without HAND (P = 0.314). Worse NP scores correlated significantly with higher HIV RNA and interferon responses in brain specimens (P < 0.001) but not with HIV RNA levels in premortem blood plasma (n = 114) or cerebrospinal fluid (n = 104). In subjects with MGNE, brain HIV RNA was slightly higher versus without MGNE (P < 0.01) and much lower versus with HIVE (P < 0.001).ConclusionsBrain HIV RNA and to a lesser extent HIV DNA are correlated with worse NP performance in the 6 months before death. Linkage occurs primarily in patients with HIVE and MGNE, and these patients could obtain added NP improvement by further reducing brain HIV while on HAART. Patients not in those groups are less certain to obtain added NP benefit.
- Published
- 2013
40. Universal definition of loss to follow-up in HIV treatment programs: a statistical analysis of 111 facilities in Africa, Asia, and Latin America.
- Author
-
Chi, Benjamin H, Yiannoutsos, Constantin T, Westfall, Andrew O, Newman, Jamie E, Zhou, Jialun, Cesar, Carina, Brinkhof, Martin WG, Mwango, Albert, Balestre, Eric, Carriquiry, Gabriela, Sirisanthana, Thira, Mukumbi, Henri, Martin, Jeffrey N, Grimsrud, Anna, Bacon, Melanie, Thiebaut, Rodolphe, and International Epidemiologic Databases to Evaluate AIDS Collaboration
- Subjects
International Epidemiologic Databases to Evaluate AIDS Collaboration ,Humans ,HIV ,HIV Infections ,Antiretroviral Therapy ,Highly Active ,Cohort Studies ,Follow-Up Studies ,Patient Compliance ,Adolescent ,Adult ,Delivery of Health Care ,Africa ,Latin America ,Asia ,Terminology as Topic ,Lost to Follow-Up ,Antiretroviral Therapy ,Highly Active ,General & Internal Medicine ,Medical and Health Sciences - Abstract
BackgroundAlthough patient attrition is recognized as a threat to the long-term success of antiretroviral therapy programs worldwide, there is no universal definition for classifying patients as lost to follow-up (LTFU). We analyzed data from health facilities across Africa, Asia, and Latin America to empirically determine a standard LTFU definition.Methods and findingsAt a set "status classification" date, patients were categorized as either "active" or "LTFU" according to different intervals from time of last clinic encounter. For each threshold, we looked forward 365 d to assess the performance and accuracy of this initial classification. The best-performing definition for LTFU had the lowest proportion of patients misclassified as active or LTFU. Observational data from 111 health facilities-representing 180,718 patients from 19 countries-were included in this study. In the primary analysis, for which data from all facilities were pooled, an interval of 180 d (95% confidence interval [CI]: 173-181 d) since last patient encounter resulted in the fewest misclassifications (7.7%, 95% CI: 7.6%-7.8%). A secondary analysis that gave equal weight to cohorts and to regions generated a similar result (175 d); however, an alternate approach that used inverse weighting for cohorts based on variance and equal weighting for regions produced a slightly lower summary measure (150 d). When examined at the facility level, the best-performing definition varied from 58 to 383 d (mean=150 d), but when a standard definition of 180 d was applied to each facility, only slight increases in misclassification (mean=1.2%, 95% CI: 1.0%-1.5%) were observed. Using this definition, the proportion of patients classified as LTFU by facility ranged from 3.1% to 45.1% (mean=19.9%, 95% CI: 19.1%-21.7%).ConclusionsBased on this evaluation, we recommend the adoption of ≥180 d since the last clinic visit as a standard LTFU definition. Such standardization is an important step to understanding the reasons that underlie patient attrition and establishing more reliable and comparable program evaluation worldwide. Please see later in the article for the Editors' Summary.
- Published
- 2011
41. Trends in the clinical characteristics of HIV-infected patients initiating antiretroviral therapy in Kenya, Uganda and Tanzania between 2002 and 2009
- Author
-
Geng, Elvin H, Hunt, Peter W, Diero, Lameck O, Kimaiyo, Sylvester, Somi, Geofrey R, Okong, Pius, Bangsberg, David R, Bwana, Mwebesa B, Cohen, Craig R, Otieno, Juliana A, Wabwire, Deo, Elul, Batya, Nash, Denis, Easterbrook, Philippa J, Braitstein, Paula, Musick, Beverly S, Martin, Jeffrey N, Yiannoutsos, Constantin T, and Wools-Kaloustian, Kara
- Abstract
Abstract Background East Africa has experienced a rapid expansion in access to antiretroviral therapy (ART) for HIV-infected patients. Regionally representative socio-demographic, laboratory and clinical characteristics of patients accessing ART over time and across sites have not been well described. Methods We conducted a cross-sectional analysis of characteristics of HIV-infected adults initiating ART between 2002 and 2009 in Kenya, Uganda and Tanzania and in the International Epidemiologic Databases to Evaluate AIDS Consortium. Characteristics associated with advanced disease (defined as either a CD4 cell count level of less than 50 cells/mm3 or a WHO Stage 4 condition) at the time of ART initiation and use of stavudine (D4T) or nevirapine (NVP) were identified using a log-link Poisson model with robust standard errors. Results Among 48, 658 patients (69% from Kenya, 22% from Uganda and 9% from Tanzania) accessing ART at 30 clinic sites, the median age at the time of ART initiation was 37 years (IQR: 31-43) and 65% were women. Pre-therapy CD4 counts rose from 87 cells/mm3 (IQR: 26-161) in 2002-03 to 154 cells/mm3 (IQR: 71-233) in 2008-09 (p < 0.001). Accessing ART at advanced disease peaked at 35% in 2005-06 and fell to 27% in 2008-09. D4T use in the initial regimen fell from a peak of 88% in 2004-05 to 59% in 2008-09, and a greater extent of decline was observed in Uganda than in Kenya and Tanzania. Self-pay for ART peaked at 18% in 2003, but fell to less than 1% by 2005. In multivariable analyses, accessing ART at advanced immunosuppression was associated with male sex, women without a history of treatment for prevention of mother to child transmission (both as compared with women with such a history) and younger age after adjusting for year of ART initiation and country of residence. Receipt of D4T in the initial regimen was associated with female sex, earlier year of ART initiation, higher WHO stage, and lower CD4 levels at ART initiation and the absence of co-prevalent tuberculosis. Conclusions Public health ART services in east Africa have improved over time, but the fraction of patients accessing ART with advanced immunosuppression is still high, men consistently access ART with more advanced disease, and D4T continues to be common in most settings. Strategies to facilitate access to ART, overcome barriers among men and reduce D4T use are needed.
- Published
- 2011
42. Chemokines in cerebrospinal fluid correlate with cerebral metabolite patterns in HIV-infected individuals
- Author
-
Letendre, Scott L., Zheng, Jialin C., Kaul, Marcus, Yiannoutsos, Constantin T., Ellis, Ronald J., Taylor, Michael J., Marquie-Beck, Jennifer, and Navia, Bradford
- Subjects
Biomedicine ,Neurology ,Immunology ,Infectious Diseases ,Virology ,Neurosciences ,CSF ,Chemokines ,Magnetic resonance spectroscopy ,HIV ,Brain - Abstract
Chemokines influence HIV neuropathogenesis by affecting the HIV life cycle, trafficking of macrophages into the nervous system, glial activation, and neuronal signaling and repair processes; however, knowledge of their relationship to in vivo measures of cerebral injury is limited. The primary objective of this study was to determine the relationship between a panel of chemokines in cerebrospinal fluid (CSF) and cerebral metabolites measured by proton magnetic resonance spectroscopy (MRS) in a cohort of HIV-infected individuals. One hundred seventy-one stored CSF specimens were assayed from HIV-infected individuals who were enrolled in two ACTG studies that evaluated the relationship between neuropsychological performance and cerebral metabolites. Concentrations of six chemokines (fractalkine, IL-8, IP-10, MCP-1, MIP-1β, and SDF-1) were measured and compared with cerebral metabolites individually and as composite neuronal, basal ganglia, and inflammatory patterns. IP-10 and MCP-1 were the chemokines most strongly associated with individual cerebral metabolites. Specifically, (1) higher IP-10 levels correlated with lower N-acetyl aspartate (NAA)/creatine (Cr) ratios in the frontal white matter and higher MI/Cr ratios in all three brain regions considered and (2) higher MCP-1 levels correlated with lower NAA/Cr ratios in frontal white matter and the parietal cortex. IP-10, MCP-1, and IL-8 had the strongest associations with patterns of cerebral metabolites. In particular, higher levels of IP-10 correlated with lower neuronal pattern scores and higher basal ganglia and inflammatory pattern scores, the same pattern which has been associated with HIV-associated neurocognitive disorders (HAND). Subgroup analysis indicated that the effects of IP-10 and IL-8 were influenced by effective antiretroviral therapy and that memantine treatment may mitigate the neuronal effects of IP-10. This study supports the role of chemokines in HAND and the validity of MRS as an assessment tool. In particular, the findings identify relationships between the immune response—particularly an interferon-inducible chemokine, IP-10—and cerebral metabolites and suggest that antiretroviral therapy and memantine modify the impact of the immune response on neurons.
- Published
- 2011
43. Assessing HIV-infected patient retention in a program of differentiated care in sub-Saharan Africa: a G-estimation approach
- Author
-
Yiannoutsos, Constantin T., primary, Wools-Kaloustian, Kara, additional, Musick, Beverly S., additional, Kosgei, Rose, additional, Kimaiyo, Sylvester, additional, and Siika, Abraham, additional
- Published
- 2023
- Full Text
- View/download PDF
44. Assessing HIV-infected patient retention in a program of differentiated care in sub-Saharan Africa: a G-estimation approach.
- Author
-
Yiannoutsos, Constantin T., Wools-Kaloustian, Kara, Musick, Beverly S., Kosgei, Rose, Kimaiyo, Sylvester, and Siika, Abraham
- Subjects
HIV ,HIV-positive persons - Abstract
Differentiated care delivery aims to simplify care of people living with HIV, reflect their preferences, reduce burdens on the healthcare system, maintain care quality and preserve resources. However, assessing program effectiveness using observational data is difficult due to confounding by indication and randomized trials may be infeasible. Also, benefits can reach patients directly, through enrollment in the program, and indirectly, by increasing quality of and accessibility to care. Low-risk express care (LREC), the program under evaluation, is a nurse-centered model which assigns patients stable on ART to a nurse every two months and a clinician every third visit, reducing annual clinician visits by two thirds. Study population is comprised of 16,832 subjects from 15 clinics in Kenya. We focus on patient retention in care based on whether the LREC program is available at a clinic and whether the patient is enrolled in LREC. We use G-estimation to assess the effect on retention of two "strategies": (i) program availability but no enrollment; (ii) enrollment at an available program; versus no program availability. Compared to no availability, LREC results in a non-significant increase in patient retention, among patients not enrolled in the program (indirect effect), while enrollment in LREC is associated with a significant extension of the time retained in care (direct effect). G-estimation provides an analytical framework useful to the assessment of similar programs using observational data. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
45. Adolescent pregnancy at antiretroviral therapy (ART) initiation: a critical barrier to retention on ART
- Author
-
Nuwagaba-Biribonwoha, Harriet, Kiragga, Agnes N, Yiannoutsos, Constantin T, Musick, Beverly S, Wools-Kaloustian, Kara K, Ayaya, Samuel, Wolf, Hilary, Lugina, Emmanuel, Ssali, John, Abrams, Elaine J, and Elul, Batya
- Subjects
Drug therapy ,Risk factors ,Dosage and administration ,Health aspects ,Teenage pregnancy -- Health aspects ,HIV infections -- Risk factors -- Drug therapy ,Youth -- Health aspects ,Antiretroviral agents -- Dosage and administration - Abstract
1 | INTRODUCTION Nearly two million adolescents (10 to 19 years) are living with HIV in sub-Saharan Africa, the most significantly HIV impacted region of the world [1]. Due to [...], Introduction: Adolescence and pregnancy are potential risk factors for loss to follow-up (LTFU) while on antiretroviral therapy (ART). We compared adolescent and adult LTFU after ART initiation to quantify the impact of age, pregnancy, and site-level factors on LTFU. Methods: We used routine clinical data for patients initiating ART as young adolescents (YA; 10 to 14 years), older adolescents (OA; 15 to 19 years) and adults ([greater than or equal to]20 years) from 2000 to 2014 at 52 health facilities affiliated with the International epidemiology Databases to Evaluate AIDS (IeDEA) East Africa collaboration. We estimated cumulative incidence (95% confidence interval, CI) of LTFU (no clinic visit for [greater than or equal to]6 months after ART initiation) and identified patient and site-level correlates of LTFU, using multivariable Cox proportional hazards models for all patients as well as individual age groups. Results: A total of 138,387 patients initiated ART, including 2496 YA, 2955 OA and 132,936 adults. Of these, 55%, 78% and 66%, respectively, were female and 0.7% of YA, 22.3% of OA and 8.3% of adults were pregnant at ART initiation. Cumulative incidence of LTFU at five years was 26.6% (24.6 to 28.6) among YA, 44.1% (41.8 to 46.3) among OA and 29.3% (29.1 to 29.6) among adults. Overall, compared to adults, the adjusted hazard ratio, aHR, (95% CI) of LTFU for OA was 1.54 (1.41 to 1.68) and 0.77 (0.69 to 0.86) for YA. Compared to males, pregnant females had higher hazard of LTFU, aHR 1.20 (1.14 to 1.27), and nonpregnant women had lower hazard aHR 0.90 (0.88 to 0.93). LTFU hazard among the OA was primarily driven by both pregnant and nonpregnant females, aHR 2.42 (1.98 to 2.95) and 1.51 (1.27 to 1.80), respectively, compared to men. The LTFU hazard ratio varied by IeDEA program. Site-level factors associated with overall lower LTFU hazard included receiving care in tertiary versus primary-care clinics aHR 0.61 (0.56 to 0.67), integrated adult and adolescent services and food ration provision aHR 0.93 (0.89 to 0.97) versus nonintegrated clinics with food ration provision, having patient support groups aHR 0.77 (0.66 to 0.90) and group adherence counselling aHR 0.61 (0.57 to 0.67). Conclusions: Older adolescents experienced higher risk of LTFU compared to YA and adults. Interventions to prevent LTFU among older adolescents are critically needed, particularly for female and/or pregnant adolescents. Keywords: antiretroviral therapy (ART); pregnancy; adolescents; Africa; ART retention; HIV outcomes
- Published
- 2018
- Full Text
- View/download PDF
46. Trends Over Time for Adolescents Enrolling in HIV Care in Kenya, Tanzania, and Uganda from 2001-2014
- Author
-
Apondi, Edith, Humphrey, John M., Sang, Edwin, Mwangi, Ann, Keter, Alfred, Musick, Beverly S., Nalugoda, Fred K., Ssali, John, Bukusi, Elizabeth, Yiannoutsos, Constantin T, Wools-Kaloustian, Kara, and Ayaya, Samuel
- Published
- 2018
- Full Text
- View/download PDF
47. Joint modeling of longitudinal and competing-risk data using cumulative incidence functions for the failure submodels accounting for potential failure cause misclassification through double sampling.
- Author
-
Thomadakis, Christos, Meligkotsidou, Loukia, Yiannoutsos, Constantin T, and Touloumi, Giota
- Subjects
PROPORTIONAL hazards models ,DISTRIBUTED parameter systems ,MEASUREMENT errors ,COMPETING risks ,HIV-positive persons - Abstract
Most of the literature on joint modeling of longitudinal and competing-risk data is based on cause-specific hazards, although modeling of the cumulative incidence function (CIF) is an easier and more direct approach to evaluate the prognosis of an event. We propose a flexible class of shared parameter models to jointly model a normally distributed marker over time and multiple causes of failure using CIFs for the survival submodels, with CIFs depending on the "true" marker value over time (i.e., removing the measurement error). The generalized odds rate transformation is applied, thus a proportional subdistribution hazards model is a special case. The requirement that the all-cause CIF should be bounded by 1 is formally considered. The proposed models are extended to account for potential failure cause misclassification, where the true failure causes are available in a small random sample of individuals. We also provide a multistate representation of the whole population by defining mutually exclusive states based on the marker values and the competing risks. Based solely on the assumed joint model, we derive fully Bayesian posterior samples for state occupation and transition probabilities. The proposed approach is evaluated in a simulation study and, as an illustration, it is fitted to real data from people with HIV. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. The effect of HIV treatment interruption on subsequent immunologic response
- Author
-
Thomadakis, Christos, primary, Yiannoutsos, Constantin T, additional, Pantazis, Nikos, additional, Diero, Lameck, additional, Mwangi, Ann, additional, Musick, Beverly S, additional, Wools-Kaloustian, Kara, additional, and Touloumi, Giota, additional
- Published
- 2023
- Full Text
- View/download PDF
49. Global HIV prevention, care and treatment services for children: a cross-sectional survey from the International Epidemiology Databases to Evaluate AIDS (IeDEA) consortium
- Author
-
Vreeman, Rachel C, primary, Yiannoutsos, Constantin T, additional, Yusoff, Nik Khairulddin Nik, additional, Wester, C William, additional, Edmonds, Andrew, additional, Ofner, Susan, additional, Davies, Mary-Ann, additional, Leroy, Valériane, additional, Lumbiganon, Pagakrong, additional, de Menezes Succi, Regina Célia, additional, Twizere, Christella, additional, Brown, Steven, additional, Bolton-Moore, Carolyn, additional, Takassi, Ounoo Elom, additional, Scanlon, Michael, additional, Martin, Roxanne, additional, and Wools-Kaloustian, Kara, additional
- Published
- 2023
- Full Text
- View/download PDF
50. Marginal and Conditional Distribution Estimation from Double-sampled Semi-competing Risks Data
- Author
-
YU, MENGGANG and YIANNOUTSOS, CONSTANTIN T.
- Published
- 2015
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.