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Although renal osteodystrophy and vitamin D analogs may be related to survival in maintenance hemodialysis (MHD) patients, most studies have examined associations between baseline values and survival without accounting for variations in clinical and laboratory measures over time. We examined associations between survival and quarterly laboratory values and administered paricalcitol in a 2-year (July 2001-June 2003) cohort of 58,058 MHD patients from all DaVita dialysis clinics in USA using both time-dependent Cox models with repeated measures and fixed-covariate Cox models with only baseline values. Whereas hypercalcemia and hyperphosphatemia were robust predictors of higher death risk in all models, the association between serum calcium and mortality was different in time-varying models. Changes in baseline calcium and phosphorus values beyond the Kidney Disease Outcome Quality Initiative recommended targets were associated with increased mortality. Associations between high serum parathyroid hormone and increased death risk were masked by case-mix characteristics of MHD patients. Time-varying serum alkaline phosphatase had an incremental association with mortality. Administration of any dose of paricalcitol was associated with improved survival in time-varying models. Controlling for nutritional markers may introduce overadjustment bias owing to their strong collinearity with osteodystrophy surrogates. Whereas both time-dependent and fixed-covariate Cox models result in similar associations between osteodystrophy indicators and survival, subtle but potentially clinically relevant differences between the two models exist, probably because fixed models do not account for variations of osteodystrophy indices and changes in medication dose over time.

Introduction: This prospective, longitudinal, community-based study, EpidemiologiCal POpulatioN STudy of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Lake CounTy, Illinois (CONTACT), investigated coronavirus disease 2019 (COVID-19) immunity, occupational risks related to SARS-CoV-2 exposure, and long-term immunoglobulin G (IgG) seroconversion kinetics., Methods: At baseline and follow up (3, 6, and 9 months), non-hospitalized adult participants provided nasal and blood serum specimens for molecular [reverse transcription polymerase chain reaction (RT-PCR)] and serological (IgG) testing (4 November 2020-30 October 2021)., Results: At baseline, 6.4% (65/1008) had evidence of current/prior SARS-CoV-2 infection. At 3, 6, and 9 months, positive PCR tests were obtained from 0.4% (3/781), 0.4% (3/733), and 0% (0/673) of participants, respectively. Positive IgG occurred at baseline and 3, 6, and 9 months in 4.5% (45/1008), 6.0% (48/799), 5.4% (39/733), and 2.8% (19/673) of participants, respectively. Of participants positive for IgG at baseline, 28 had a negative IgG test at a follow-up visit; of those 28,  21 had their first negative IgG test within 6 months. Participants were more likely to retain positive IgG if they were 18-29 years of age, were male, or had medium-high/high-risk occupations. A high vaccination rate (70% received ≥ 1 dose by 9 months) was observed. Influence of occupational status or characteristics on transmission and IgG, and COVID-19 vaccination trends, are shown., Conclusions: This study expands on prior studies assessing COVID-19 immunity and IgG seroconversion by including both RT-PCR and serologic testing and longitudinal follow-up of study participants. We observed decreased infection rates over the 9 month follow-up period as well as a decline in IgG persistency after 6 months. The findings from this community-based study regarding vaccinate rates, infection rates by PCR, and IgG persistency over time can help improve our understanding of COVID-19 immunity, occupational risks related to SARS-CoV-2 exposure, and the kinetics of long-term IgG seroconversion, which is important to help guide local and national mitigation strategies., Clinical Trial Registration: NCT04611230., (© 2024. The Author(s).)

This study investigated whether systemic drug prescribing for psoriasis varies by season and other exacerbating factors. Eligible patients with psoriasis were assessed for each season for initiation, discontinuation, and switching of systemic drugs. A total of 360,787 patients were at risk of initiating any systemic drugs in 2016‒2019; 39,572 patients and 35,388 patients were at risk of drug discontinuation or switching to a biologic and a nonbiologic systemic drug, respectively. The initiation of biologic therapy in 2016‒2019 peaked in spring (1.28%), followed by summer (1.11%), fall (1.08%), and winter (1.01%). Nonbiologic systemic drugs followed a similar pattern. Those aged 30‒39 years, male, those with psoriatic arthritis, those who live in the South region, those who live in areas with lower altitudes, and those who live in areas with lower humidity had higher initiation with the same seasonality pattern. Discontinuation of biologic drugs peaked in summer, and switching of biologics was highest in spring. Season is associated with initiation, discontinuation, and switching, although seasonality pattern is less clear for nonbiologic systemic drugs. Approximately 14,280 more patients with psoriasis in the United States are estimated to initiate a biologic in spring than in other seasons, and over 840 more biologic users switched in spring than in winter. The findings may provide evidence for healthcare resource planning in psoriasis management., (© 2023 The Authors.)

Introduction: EpidemiologiCal POpulatioN STudy of SARS-CoV-2 in Lake CounTy, Illinois (CONTACT) is an observational, epidemiological study with a 9-month longitudinal follow-up of nonhospitalized persons aged 18 years or older currently living or employed in Lake County, IL. We describe the study design and report baseline characteristics of the study participants, including the proportion of participants with acute or previous SARS-CoV-2 infection at enrollment., Methods: At enrollment and subsequent timepoints, participants recruited through digital and paper-based advertising campaigns reported their occupational and school-based exposure, risk factors, and behaviors, and provided nasal and serum specimens. Stratified enrichment was used to enhance enrollment into medium- and higher-risk groups within four occupational risk groups for SARS-CoV-2 infection. RT-PCR and serologic (IgG) testing were conducted to detect acute or previous SARS-CoV-2 infection in participants, respectively., Results: Between November 2020 and January 2021, 1008 participants (female 70.7%, mean age ± SD 51 ± 13.8 years) completed the questionnaire and diagnostic testing. Among participants, 41.8% (n = 421) were considered low risk, 24.6% (n = 248) were medium-to-low risk, 22.3% (n = 225) were medium-to-high risk, and 11.3% (n = 114) were high risk. Of 56 (5.6%) participants with evidence of acute or previous SARS-CoV-2 infection at baseline, 11 (19.6%) were RT-PCR-positive, 36 (64.3%) were IgG-seropositive, and 9 (16.1%) were positive by both assays. Participants who were adherent vs nonadherent to social distancing measures (odds ratio [95% CI] 0.8 [0.4-1.8]) were less likely, while those in higher vs lower occupational risk groups (2.0 [1.0-4.4]) were more likely to have evidence for acute or previous SARS-CoV-2 infection., Conclusion: In fall/winter 2020/21, 5.6% of adults in a Lake County convenience sample had evidence for acute or previous SARS-CoV-2 infection at baseline. Nonadherence to social distancing measures and high-risk professions were associated with SARS-CoV-2 infection. The study is ongoing and future analyses will assess infection status over time., Clinical Trial Registration: NCT04611230., (© 2022. The Author(s).)

Purpose: Accurately identifying patients with psoriasis (PsO) is crucial for generating real-world evidence on PsO disease course and treatment utilization., Methods: We developed nine claims-based algorithms for PsO using a combination of the International Classification of Diseases (ICD)-9 codes, specialist visit, and medication dispensing using Medicare linked to electronic health records data (2013-2014) in two healthcare provider networks in Boston, Massachusetts. We calculated positive predictive value (PPV) and 95% confidence interval (CI) for each algorithm using the treating physician's diagnosis of PsO via chart review as the gold standard. Among the confirmed PsO cases, we assessed their PsO disease activity., Results: The nine claims-based algorithms identified 990 unique patient records. Of those, 918 (92.7%) with adequate information were reviewed. The PPV of the algorithms ranged from 65.1 to 82.9%. An algorithm defined as ≥1 ICD-9 diagnosis code for PsO and ≥1 prescription claim for topical vitamin D agents showed the highest PPV (82.9%). The PPV of the algorithm requiring ≥2 ICD-9 diagnosis codes and ≥1 prescription claim for PsO treatment excluding topical steroids was 81.1% but higher (82.5%) when ≥1 diagnosis was from a dermatologist. Among 411 PsO patients with adequate information on PsO disease activity in EHRs, 1.5-5.8% had no disease activity, 31.3-36.8% mild, and 26.9-35.1% moderate-to-severe across the algorithms., Conclusions: Claims-based algorithms based on a combination of PsO diagnosis codes and dispensing for PsO-specific treatments had a moderate-to-high PPV. These algorithms can serve as a useful tool to identify patients with PsO in future real-world data pharmacoepidemiologic studies., (© 2021 John Wiley & Sons Ltd.)

Background: Women with endometriosis are prescribed opioids for pain relief but may be vulnerable to chronic opioid use given their comorbidity profile., Methods: A cohort study was conducted in the Clinformatics™ DataMart database between 2006 and 2017 comparing women aged 18-50 years with endometriosis (N = 36 373) to those without (N = 2 172 936) in terms of risk of chronic opioid use, opioid dependence diagnosis, and opioid overdose. Chronic opioid use was defined as ≥120 days' supply dispensed or ≥10 fills of an opioid during any 365-day interval. Among women with endometriosis, we evaluated factors associated with higher risk of chronic opioid use and quantified the risk of complications associated with the use of opioids., Results: Women with endometriosis were at greater risk for chronic opioid use (OR: 3.76; 95%CI: 3.57-3.96), dependence (OR: 2.73, 95%CI: 2.38-3.13) and overdose (OR: 4.34, 95%CI: 3.06-6.15) compared to women without. Chronic users displayed dose escalation and increase in days supplied over time, as well as co-prescribing with benzodiazepines and sedatives. Approximately 34% of chronic users developed constipation, 20% experienced falls, and 8% reported dizziness. Among endometriosis patients, women in younger age groups, those with other comorbidities associated with pain symptoms, as well as those with depression or anxiety were at a higher risk of developing chronic opioid use., Conclusions: Women with endometriosis had a four times greater risk of chronic opioid use compared to women without. Multimorbidity among these patients was associated with the elevated risk of chronic opioid use and should be taken into account during treatment selection., (© 2021 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.)

Background: Completeness of adverse event (AE) reports is an important component of quality for good pharmacovigilance practices. We aimed to evaluate the impact of incorporating a measure of completeness of AE reports on quantitative signal detection., Methods: An internal safety database from a global pharmaceutical company was used in the analysis. vigiGrade, an index score of completeness, was derived for each AE report. Data from various patient support programs (PSPs) were categorized based on average vigiGrade score per PSP. Performance of signal detection was compared between: (1) weighting and not weighting by vigiGrade score; and, (2) well documented and poorly documented PSPs using sensitivity, specificity, area under the receiver operating characteristics curve (AUC) and time-to-signal detection., Results: The ability to detect signals did not differ significantly when weighting by vigiGrade score [sensitivity (50% vs. 45%, p = 1), specificity (82.8% vs. 82.8%, p = 1), AUC (0.66 vs. 0.63, p = 0.051) or time-to-signal detection (HR 0.81, p = 0.63)] compared to not weighting. Well documented PSPs were better at detecting signals than poorly documented PSPs (AUC 0.66 vs. 0.52; p = 0.041) but time-to-signal detection did not differ significantly (HR 1.54, p = 0.42)., Conclusion: Completeness of AE reports did not significantly impact the ability to detect signals when weighting by vigiGrade score or restricting the database based on the level of completeness. While the vigiGrade helps provide quality assessments of AE reports and prioritize cases for review, our findings indicate the tool might not be useful for quantitative signal detection when used by itself.

Elagolix, a gonadotrophin-releasing hormone antagonist, is used in premenopausal women with endometriosis. There is a risk of bone loss with elagolix, but the long-term effects of BMD loss later in life cannot be directly assessed and has not been quantified. To address this gap in knowledge, this study indirectly estimated the impact of elagolix on postmenopausal fracture risk. BMD change in premenopausal women with endometriosis treated with elagolix was modeled from the phase III program data (elagolix group) and used to simulate treatment effects on (fracture risk assessment tool estimated) 10-year risks of hip and major osteoporotic fracture in women ages 50 to 79 years from the 2005-2010 National Health and Nutrition Examination Survey (NHANES; N = 2303). Change in the proportion of women reaching risk-based antiosteoporotic treatment thresholds was also estimated. For elagolix versus NHANES, median 10-year risk of major osteoporotic fracture was 4.73% versus 4.70% in women ages 50 to 59 years, 7.03% versus 6.97% in women ages 60 to 69 years, and 10.83% versus 10.68% in women ages 70 to 79 years. Median 10-year risk of hip fracture in these same groups was 0.19% versus 0.18% for women ages 50 to 59 years, 0.51% versus 0.49% for women 60 to 69 years, and 2.22% versus 2.14% for women 70 to 79 years. The proportion of women reaching risk-based antiosteoporotic treatment thresholds caused by elagolix 150 mg daily for 12 months was 0.36% higher at age 50 to 59 years, 0.23% at age 60 to 69 years, and 1.79% at age 70 to 79 years. The number needed to harm was 643 for one additional hip fracture and 454 for one additional major osteoporotic fracture. Results were similar for elagolix 200 mg twice a day for 3 months. In the modeled scenarios, elagolix had minimal impact on long-term risk of fracture and reaching risk-based treatment thresholds. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research., (© 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.)

Objectives: Marketing authorization holder (MAH)-sponsored patient support programs (PSPs) are a major source of adverse event (AE) reports. The impact of reports from PSPs on the ability to detect AE signals is unclear. We compared signal detection performance using data from PSPs vs. non-PSP sources, and between PSPs providing clinical services vs. PSPs not providing clinical services., Methods: Data were obtained from an internal safety database for a global pharmaceutical company 2015-2017. We assessed whether signals were detected for the reference drug-AE pairs using data from PSPs vs. non-PSP sources, and among different PSP services. The performance was evaluated by four measures including area under the receiver operating characteristic curve (AUC) and time-to-signal detection., Results: While the majority of reports were from PSPs, non-PSP sources were better and faster at detecting signals (AUC 0.63 vs. 0.41, p = 0.035; HR 3.52, p = 0.014) compared to PSPs. Within PSPs, PSPs providing clinical services were marginally better at detecting signals (AUC 0.60 vs. 0.41, p = 0.053) but not faster compared to PSPs not providing clinical services., Conclusion: Reports of AEs from PSPs had worse signal detection performance compared to non-PSP sources. Pharmacovigilance experts should be mindful when using databases that contain reports from PSPs for signal detection.

Objectives: To assess incidence rates (IRs) of VTE in patients with rheumatoid arthritis (RA) on different DMARDs and DMARD switchers., Methods: Adults with RA on a DMARD between 2007 and 2017 were studied in a US claims database. Conventional synthetic DMARD (csDMARD) users, first biologic/targeted synthetic DMARD (b/tsDMARD) users and b/tsDMARD switchers (from a b/tsDMARD to another b/tsDMARD) were followed for inpatient VTE (pulmonary embolism (PE)/deep vein thrombosis (DVT)). Crude and adjusted IR and 95% CIs of VTE were estimated. HRs for VTE were estimated via Cox regression. VTE risk was also evaluated by number of switches between b/tsDMARDs and in patients without a VTE history., Results: The age and sex standardised IR (95% CI) of VTE (per 100 person-years) was 0.86 (0.70 to 1.03), 0.60 (0.52 to 0.68) and 0.58 (0.51 to 0.65) for b/tsDMARD switchers, first b/tsDMARD users and csDMARD users, respectively. After adjustment, b/tsDMARD switchers had an increased risk of VTE, compared with csDMARD users, HR adj (95% CI) being 1.36 (1.16 to 1.58), 1.36 (1.13 to 1.63) and 1.47 (1.18 to 1.83) for VTE, DVT and PE, respectively. Compared with first b/tsDMARD users, the HR adj (95% CI) for VTE was 1.35 (1.15 to 1.60) for first b/tsDMARD switchers and 1.48 (1.19 to 1.85) for second b/tsDMARD switchers., Conclusions: In RA, b/tsDMARD switchers have a higher VTE risk compared with csDMARD users and first b/tsDMARD users. Switching b/tsDMARDs may be a proxy for higher disease severity or poorly controlled RA and an important confounder to consider in obtaining unbiased estimates of VTE risk in observational RA safety studies., Competing Interests: Competing interests: HL, RD, DG, RDK, BH and SSI are employees of AbbVie and own AbbVie stocks or stock options at the time of the study. JRC has received consulting fees from AbbVie, Amgen, BMS, CORRONA, Janssen, Lilly, Myriad and Pfizer; and research funding from AbbVie, Amgen, BMS, CORRONA, Janssen, Lilly, Myriad and Pfizer., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY. Published by BMJ.)

We examined claims-based approaches for identifying a study population free of coronary heart disease (CHD) using data from 8,937 US blacks and whites enrolled during 2003-2007 in a prospective cohort study linked to Medicare claims. Our goal was to minimize the percentage of persons at study entry with self-reported CHD (previous myocardial infarction or coronary revascularization). We assembled 6 cohorts without CHD claims by requiring 6 months, 1 year, or 2 years of continuous Medicare fee-for-service insurance coverage prior to study entry and using either a fixed-window or all-available look-back period. We examined adding CHD-related claims to our "base algorithm," which included claims for myocardial infarction and coronary revascularization. Using a 6-month fixed-window look-back period, 17.8% of participants without claims in the base algorithm reported having CHD. This was reduced to 3.6% using an all-available look-back period and adding other CHD claims to the base algorithm. Among cohorts using all-available look-back periods, increasing the length of continuous coverage from 6 months to 1 or 2 years reduced the sample size available without lowering the percentage of persons with self-reported CHD. This analysis demonstrates approaches for developing a CHD-free cohort using Medicare claims., (© The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Altered bone structure and function contribute to the high rates of fractures in dialysis patients compared to the general population. Fracture events may increase the risk of subsequent adverse clinical outcomes. Here we assessed the incidence of post-fracture morbidity and mortality in an international cohort of 34,579 in-center hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS). We estimated country-specific rates of fractures requiring a hospital admission and associated length of stay in the hospital. Incidence rates of death and of a composite event of death/rehospitalization were estimated for 1 year after fracture. Overall, 3% of participants experienced a fracture. Fracture incidence varied across countries, from 12 events/1000 patient-years (PY) in Japan to 45/1000 PY in Belgium. In all countries, fracture rates were higher in the hemodialysis group compared to those reported for the general population. Median length of stay ranged from 7 to 37 days in the United States and Japan, respectively. In most countries, postfracture mortality rates exceeded 500/1000 PY and death/rehospitalization rates exceeded 1500/1000 PY. Fracture patients had higher unadjusted rates of death (3.7-fold) and death/rehospitalization (4.0-fold) compared to the overall DOPPS population. Mortality and hospitalization rates were highest in the first month after the fracture and declined thereafter. Thus, the high frequency of fractures and increased adverse outcomes following a fracture pose a significant health burden for dialysis patients. Fracture prevention strategies should be identified and applied broadly in nephrology practices.

Background and Objectives: Parathyroid hormone, calcium, and phosphate have been independently associated with cardiovascular event risk. Because these parameters may be on the same causal pathway and have been proposed as quality measures, an integrated approach to estimating event risks is needed., Design, Setting, Participants, & Measurements: Prevalent dialysis patients were followed from August 31, 2005 to December 31, 2006. A two-stage modeling approach was used. First, the 16-month probabilities of death and composite end point of death or cardiovascular hospitalization were estimated and adjusted for potential confounders. Second, patients were categorized into 1 of 36 possible phenotypes using average parathyroid hormone, calcium, and phosphate values over a 4-month baseline period. Associations among phenotypes and outcomes were estimated and adjusted for the underlying event risk estimated from the first model stage., Results: Of 26,221 patients, 98.5% of patients were in 22 groups with at least 100 patients and 20% of patients were in the reference group defined using guideline-based reference ranges for parathyroid hormone, calcium, and phosphate. Within the 22 most common phenotypes, 20% of patients were in groups with significantly (P<0.05) higher risk of death and 54% of patients were in groups with significantly higher risk of the composite end point relative to the in-target reference group. Increased risks ranged from 15% to 47% for death and from 8% to 55% for the composite. More than 40% of all patients were in the three largest groups with elevated composite end point risk (high parathyroid hormone, target calcium, and high phosphate; target high parathyroid hormone, target calcium, and high phosphate; and target high parathyroid hormone, target calcium, and target phosphate)., Conclusion: After adjusting for baseline risk, phenotypes defined by categories of parathyroid hormone, calcium, and phosphate identify patients at higher risk of death and cardiovascular hospitalization. Identifying common high-risk phenotypes may inform clinical interventions and policies related to quality of care.

Background: Changes in mineral and bone disorder treatment patterns and demographic changes in the dialysis population may have influenced hip fracture rates in US dialysis patients in 1993-2010., Study Design: Retrospective follow-up study analyzing trends over time in hospitalized hip fracture rates., Setting & Participants: Using Medicare data, we created 2 point-prevalent study cohorts for each study year. Hemodialysis cohorts included patients with Medicare as primary payer receiving hemodialysis in the United States on January 1 of each year; non-end-stage renal disease (ESRD) cohorts included Medicare beneficiaries 66 years or older on January 1 of each year., Factors: Age, sex, race, primary cause of ESRD, dual Medicare/Medicaid enrollment status, comorbid conditions., Outcomes: Hip fracture rates., Measurements: Unadjusted hip fracture rates measured using number of events per 1,000 person-years in each year, then adjusted for patient characteristics. Poisson models estimated strata-specific event rates., Results: The observed number of first hospitalized hip fracture events and the adjusted hip fracture rate increased steadily from 1993 (831 events; 11.9/1,000 person-years), peaked in 2004 (3,256 events; 21.9/1,000 person-years), and decreased through 2010 (2,912 events; 16.6/1,000 person-years). The trend for the subset of hemodialysis patients 66 years or older was similar to the trend for the full hemodialysis cohort; however, it differed markedly in magnitude and pattern from the non-ESRD Medicare cohort, for which rates were substantially lower and slowly decreasing since 1996., Limitations: Unable to provide causal explanations for observed changes; hip fractures identified through inpatient episodes; results do not describe hemodialysis patients without Medicare Parts A and B; laboratory values unavailable in the Medicare data set., Conclusions: Temporal trends in hip fracture rates among Medicare hemodialysis patients differ markedly from the steadily decreasing trend in non-ESRD Medicare beneficiaries, showing a relatively rapid increase until 2004 and relatively rapid decrease thereafter. Further research is needed to define associated factors., (Copyright © 2013 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Anemia is associated with decreased functional capacity, reduced quality of life, and worsened outcomes among patients with heart failure (HF) due to reduced left ventricular ejection fraction (HFREF). We sought to evaluate the independent effect of anemia on clinical outcomes among those with HFREF., Hypothesis: Anemia is associated with cardiovascular events in patients with heart failure., Methods: The HF-ACTION trial was a prospective, randomized trial of exercise therapy vs usual care in 2331 patients with HFREF. Patients with New York Heart Association class II to IV HF and left ventricular ejection fractions of ≤ 35% were recruited. Hemoglobin (Hb) was measured up to 1 year prior to entry and was stratified by quintile. Anemia was defined as baseline Hb <13 g/dL and <12 g/dL in men and women, respectively. Hemoglobin was assessed in 2 models: a global prediction model that had been previously developed, and a modified model including variables associated with anemia and the studied outcomes., Results: Hemoglobin was available at baseline in 1763 subjects (76% of total study population); their median age was 59.0 years, 73% were male, and 62% were Caucasian. The prevalence of anemia was 515/1763 (29%). Older age, female sex, African American race, diabetes, hypertension, and lower estimated glomerular filtration rates were all more frequent in lower Hb quintiles. Over a median follow-up of 30 months, the primary outcome of all-cause mortality or all-cause hospitalization occurred in 78% of those with anemia and 64% in those without (P < 0.001). The secondary outcomes of all-cause mortality alone,cardiovascular (CV) mortality or CV hospitalization, and CV mortality or HF hospitalization occurred in 23% vs 15%, 67% vs 54%, and 44 vs 29%, respectively (P < 0.001). Heart failure hospitalizations occurred in 36% vs 22%, and urgent outpatient visits for HF exacerbations occurred in 67% and 55%, respectively (P < 0.001). For the global model, there was an association observed for anemia and all-cause mortality or hospitalization (adjusted hazard ratio [HR]: 1.15, 95% confidence interval [CI]: 1.01-1.32, P = 0.04), but other outcomes were not significant at P < 0.05. In the modified model, the adjusted HR for anemia and the primary outcome of all-cause mortality or all-cause hospitalization was 1.25 (95% CI: 1.10-1.42, P < 0.001). There were independent associations between anemia and all-cause death (HR: 1.11, 95% CI: 0.87-1.42, P = 0.38), CV death or CV hospitalization (HR: 1.16, 95% CI: 1.01-1.33, P = 0.035), and CV death and HF hospitalization (HR: 1.27, 95% CI: 1.06-1.51, P = 0.008)., Conclusions: Anemia modestly is associated with increased rates of death, hospitalization, and HF exacerbation in patients with chronic HFREF. After adjusting for other important covariates, anemia is independently associated with an excess hazard for all-cause mortality and all-cause hospitalization. Anemia is also associated with combinations of CV death and CV/HF hospitalizations as composite endpoints., (© 2013 Wiley Periodicals, Inc.)

Patients with ESRD have a substantially increased risk of bone fractures, but the burden of fractures has not been sufficiently characterized in this population. Here, we analyzed fracture rates and postdischarge outcomes using Medicare data from hemodialysis patients in the United States between 2000 and 2009. We assessed adjusted quarterly fracture rates (inpatient and outpatient) and consequences of postfracture hospitalization for seven categories of fracture location. Pelvis/hip, vertebral, and lower leg fractures were the most prevalent fracture types. Pelvis/hip fractures declined slightly from 29.6 to 20.6 per 1000 patient-years between early 2000 and late 2009, but the incidence rates for all other fracture types remained relatively constant. Median lengths of stay for the primary fracture hospitalization ranged from 5 days (interquartile range [IQR], 3-9 days) for forearm/wrist fractures to 8 days (IQR, 5-12 days) for femur fractures. The proportion of patients discharged from the primary hospitalization to a skilled-nursing facility ranged from 28% (ribs/sternum) to 47% (pelvis/hip). A negative binomial regression model suggested that patients had an adjusted mean of 3.8-5.2 additional hospitalizations during the year after discharge from the index hospitalization, varying by fracture type, comprising a mean of 33-52 inpatient days. Case-mix-adjusted mortality rates after discharge ranged from 0.43 to 0.91 per patient-year and were highest for vertebral, pelvis/hip, and femur fractures. In conclusion, fractures in the dialysis population are common and are associated with a substantially increased risk for death and hospitalization.

Background: There are few data available on low hemoglobin and incident falls in the general U.S. population., Methods: Of 30,239 black and white U.S. adults ≥45 years in the population-based REasons for Geographic And Racial Differences in Stroke study, 16,782 had hemoglobin measured at baseline and follow-up data on falls. Hemoglobin was categorized by 1.0 g/dL increments relative to the World Health Organization anemia threshold (<13.0 g/dL for men, <12.0 g/dL for women). Recurrent falls (≥2 falls in the 6 months after baseline) were assessed during a telephone interview., Results: Recurrent falls occurred in 3.9% of men and 4.8% of women. Compared with those with a hemoglobin level 1 to 2 g/dL above the anemia cut-off, multivariable adjusted odds ratios (95% confidence intervals) for recurrent falls associated with hemoglobin levels ≥3, 2 to <3 and 0 to 1 g/dL above the cut-off point, and 0 to <1 and ≥1 g/dL below the cut-off point were 0.73 (0.45-1.19), 0.84 (0.57-1.24), 1.29 (0.88-1.90), 1.32 (0.0.80-1.2.18) and 2.12 (1.23-3.63), respectively, among men (linear trend P < 0.001), and 1.59 (1.10-2.3), 1.24 (0.95-1.62), 1.42(1.11-1.81), 1.28 (0.91-1.80) and 1.76 (1.13-2.74), respectively, among women (linear trend P = 0.45; quadratic trend P = 0.016)., Conclusions: Among men, lower hemoglobin levels were associated with an increased risk for recurrent falls. Although our findings suggest an increased risk for recurrent falls at both lower and higher hemoglobin levels among women, these findings should be confirmed in subsequent studies.

Purpose: When medications are modified in response to changing clinical conditions, confounding by indication arises that cannot be controlled using traditional adjustment. Inverse probability of treatment weights (IPTWs) can address this confounding given assumptions of no unmeasured confounders and that all patients have a positive probability of receiving all levels of treatment (positivity). We sought to explore these assumptions empirically in the context of epoetin-alfa (EPO) dosing and mortality., Methods: We developed a single set of IPTWs for seven EPO dose categories and evaluated achieved covariate balance, mortality hazard ratios, and confidence intervals using two levels of treatment model parameterization and weight deletion., Results: We found that IPTWs improved covariate balance for most confounders, but was not optimal for prior hemoglobin. Including more predictors in the treatment model or retaining highly weighted individuals resulted in estimates closer to the null, although precision decreased., Conclusion: We chose to evaluate weights and covariate balance at a single time-point to facilitate an empirical analysis of model assumptions. These same assumptions are applicable to a time-dependent analysis, although empirical examination is not straight forward in that case. We find that the inclusion of rare treatment decisions and the high weights that result is needed for covariate balance under the positivity assumption. Removal of these influential weights can result in bias in either direction relative to the original confounding. It is therefore important to determine the reason for these rare patterns and whether inference is possible for all treatment levels., (Copyright © 2012 John Wiley & Sons, Ltd.)

Background/aims: Data describing real-world use and effectiveness of cinacalcet are limited. We aimed to characterize predictors of treatment and changes in secondary hyperparathyroidism (SHPT) biochemistry after cinacalcet initiation., Methods: We studied 25,250 in-center hemodialysis patients from a large dialysis provider, alive through November 2004, with no prior cinacalcet prescription. Patients were followed until initiation of cinacalcet, censoring, death, or July 31, 2007. Initiators were further followed for dose titration and discontinuation. Predictors of these events were evaluated using Cox proportional hazards modeling. Biochemical parameters and other SHPT medication use were compared between baseline, pre-initiation, and post-initiation time points., Results: Over an average of 1.25 years of follow-up, 30% of patients initiated cinacalcet therapy. Between baseline and initiation (mean of 386 days), parathyroid hormone (PTH) and phosphorus levels increased 78 and 7%, respectively, in these patients. After adjustment, cinacalcet initiation was associated with higher SHPT severity, younger age, African-American race, higher phosphorus levels, and more comorbidity. Within 1 month of initiation, median PTH was reduced by 15-30% and phosphorus by 3-5%. Reductions were sustained or increased over 12 months, depending on initiating PTH level and whether dose up-titration occurred. Discontinuation was common, although many patients reinitiated., Conclusions: A substantial proportion of patients experienced SHPT progression and initiated cinacalcet treatment. Reductions in biochemistry varied by disease severity and whether doses were titrated., (Copyright © 2013 S. Karger AG, Basel.)

Background/aims: African-Americans with end-stage renal disease receiving dialysis have more severe secondary hyperparathyroidism than Whites. We aimed to assess racial differences in clinical use of cinacalcet., Methods: This retrospective cohort study used data from DaVita, Inc., for 45,589 prevalent hemodialysis patients, August 2004, linked to Centers for Medicare & Medicaid Services data, with follow-up through July 2007. Patients with Medicare as primary payer, intravenous vitamin D use, or weighted mean parathyroid hormone (PTH) level >150 pg/ml at baseline (August 1-October 31, 2004) were included. Cox proportional hazard modeling was used to evaluate race and other demographic and clinical characteristics as predictors of cinacalcet initiation, titration, and discontinuation., Results: Of 16,897 included patients, 7,674 (45.4%) were African-American and 9,223 (54.6%) were white; 53.2% of cinacalcet users were African-American. Cinacalcet was prescribed for 47.7% of African-Americans and 34.5% of Whites, and for a greater percentage of African-Americans at higher doses at each PTH strata. After covariate adjustment, African-Americans were more likely than Whites to receive cinacalcet prescriptions (hazard ratio 1.17, p < 0.001). The direction and magnitude of this effect appeared to vary by age, baseline PTH, and calcium, and by elemental calcium use. African-Americans were less likely than Whites to have prescriptions discontinued and slightly more likely to undergo uptitration (hazard ratio 1.09, 95% confidence interval 0.995-1.188), but this relationship lacked statistical significance., Conclusion: Cinacalcet is prescribed more commonly and at higher initial doses for African-Americans than for Whites to manage secondary hyperparathyroidism.

Confounding is an important source of bias in nonexperimental studies, arising when the effect of an exposure on the occurrence of an outcome is distorted by the effect of some other factor. In nonexperimental studies of patients with CKD or who are on chronic dialysis, confounding is a significant concern owing to the high burden of comorbid disease, extent of required clinical management, and high frequency of adverse clinical events in this patient population. Confounding can be addressed in both the design stage (restriction, accurate measurement of confounders) and analysis stage (stratification, multivariable adjustment, propensity scores, marginal structural models, instrumental variable) of a study. Time-dependent confounding and confounding by indication are 2 special cases of confounding that can arise in studies of treatment effects and may require more sophisticated analytic techniques to adequately address. The availability and expanded use of large health care databases have ensured greater precision and have now placed the focus on validity. Addressing the major threats to validity, such as confounding, should be a first-order concern., (© 2012 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose: Elevated levels of phosphorus (P) and calcium (Ca) have been shown in observational studies to be associated with an increased risk of adverse clinical outcomes including mortality. Vitamin D sterols have been shown to increase the risk of hypercalcemia and hyperphosphatemia in clinical trials. We sought to explore these risks in real-world clinical practice., Methods: We employed a case-crossover design, which eliminates confounding by non-time-varying patient characteristics by comparing, within each patient, vitamin D doses before the event with those at an earlier period. Using this method, we estimated the risk of hypercalcemic (Ca ≥ 11 g/dL) and hyperphosphatemic (P ≥ 8 g/dL) events for patients at different dose quartiles of vitamin D relative to patients not on a vitamin D sterol., Results: There was a dose-dependent association between vitamin D dose quartile and risk of hypercalcemia or hyperphosphatemia. In adjusted analyses, each increase in vitamin D quartile was associated with a multiple of hypercalcemia risk between 1.7 and 19 times compared with those not on vitamin D and a multiple of hyperphosphatemia risk between 1.8 and 4., Conclusion: Use of vitamin D sterols is associated with an increased risk of hypercalcemic and hyperphosphatemic events in real-world clinical practice. Other potential predictors of these events, such as phosphate binder use and dialysate Ca levels, were not examined in this analysis., (Copyright © 2011 John Wiley & Sons, Ltd.)

HIV-1-infected adults over the age of 50 years progress to AIDS more rapidly than adults in their twenties or thirties. In addition, HIV-1-infected individuals receiving antiretroviral therapy (ART) present with clinical diseases, such as various cancers and liver disease, more commonly seen in older uninfected adults. These observations suggest that HIV-1 infection in older persons can have detrimental immunological effects that are not completely reversed by ART. As naïve T-cells are critically important in responses to neoantigens, we first analyzed two subsets (CD45RA(+)CD31(+) and CD45RA(+)CD31(-)) within the naïve CD4(+) T-cell compartment in young (20-32 years old) and older (39-58 years old), ART-naïve, HIV-1 seropositive individuals within 1-3 years of infection and in age-matched seronegative controls. HIV-1 infection in the young cohort was associated with lower absolute numbers of, and shorter telomere lengths within, both CD45RA(+)CD31(+)CD4(+) and CD45RA(+)CD31(-)CD4(+) T-cell subsets in comparison to age-matched seronegative controls, changes that resembled seronegative individuals who were decades older. Longitudinal analysis provided evidence of thymic emigration and reconstitution of CD45RA(+)CD31(+)CD4(+) T-cells two years post-ART, but minimal reconstitution of the CD45RA(+)CD31(-)CD4(+) subset, which could impair de novo immune responses. For both ART-naïve and ART-treated HIV-1-infected adults, a renewable pool of thymic emigrants is necessary to maintain CD4(+) T-cell homeostasis. Overall, these results offer a partial explanation both for the faster disease progression of older adults and the observation that viral responders to ART present with clinical diseases associated with older adults.

Background and Objectives: Observational studies relating epoetin alfa (EPO) dose and mortality frequently use analytic methods that do not control time-dependent confounding by indication (CBI). The relationship between EPO dose and 1-year mortality, adjusting for the effects of time-dependent CBI, was examined using a marginal structural model., Design, Setting, Participants, & Measurements: This retrospective cohort study included 27,791 hemodialysis patients between July 2000 and June 2002. Patients were grouped at successive 2-wk intervals into a zero-dose category or four nonzero-dose categories. Ordinal regression was used to calculate inverse probability of treatment weights of patients receiving their own dose level given their covariate and treatment history. Three treatment models with an increasing number of treatment predictors were evaluated to assess the effect of model specification. A small number of excessively large patient weights were truncated. Relative hazards for higher-dose groups compared with the lowest nonzero-dose group varied by treatment model specification and by level of weight truncation., Results: Results differed appreciably between the simplest treatment model, which incorporated only hemoglobin and EPO dosing history with 2% weight truncation (hazard ratio: 1.51; 95% confidence interval: 1.09, 1.89 for highest-dose patients), and the most comprehensive treatment model with 1% weight truncation (hazard ratio: 0.98; 95% confidence interval: 0.76, 1.74)., Conclusions: There is appreciable CBI at higher EPO doses, and EPO dose was not associated with increased mortality in marginal structural model analyses that more completely addressed this confounding.

Findings from randomized controlled trials examining the efficacy of therapy with erythropoiesis-stimulating agents (ESAs) to normalize hemoglobin levels in patients with chronic kidney disease or kidney failure have raised questions regarding the safety of this class of drugs. However, no trial to date has specifically assessed the safety of ESA-dosing algorithms used to achieve the lower hemoglobin targets typically using in clinical practice. Although a wealth of nonexperimental data is available for dialysis patients, analyses based on these data are more susceptible to confounding bias than randomized controlled trials. Conducting valid pharmacoepidemiologic studies of drug effects in hemodialysis patients is complicated by the extent of their comorbidities, frequent hospitalizations, various concomitant medications, and an exceedingly high mortality rate. The need for greater ESA doses for the treatment of anemia in sicker patients potentially and plausibly generates confounding by indication, the control of which is complicated by the presence of time-dependent confounding. Here, we describe sources of bias in nonexperimental studies of ESA therapy in hemodialysis patients and critically appraise analytical methods that may help minimize bias in such studies.

Background and Objectives: Among hemodialysis patients, achieved hemoglobin is associated with Epoetin alfa dose and erythropoietin responsiveness. A prospective erythropoietin responsiveness measure was developed and its association with mortality evaluated., Design, Setting, Participants, & Measurements: Data from 321 participants were used and randomized to the hematocrit normalization arm of the Normal Hematocrit Cardiac Trial. Subjects were to receive a 50% Epoetin alfa dose increase at randomization. The prospective erythropoietin responsiveness measure was defined as the ratio of weekly hematocrit change (over the 3 wk after randomization) per Epoetin alfa dose increase (1000 IU/wk) corresponding to the mandated 50% dose increase at randomization. The distribution of responsiveness was divided into quartiles. Over a 1-yr follow-up, Cox proportional hazard modeling evaluated associations between this responsiveness measure and mortality., Results: Erythropoietin responsiveness values ranged from -2.1% to 2.4% per week per 1000 IU. Although subjects were similar across response quartiles, mortality ranged between 14% and 34% among subjects in the highest and lowest response quartiles (P = 0.0004), respectively. After adjusting for baseline prognostic indicators, highest versus lowest responsiveness was associated with a hazard ratio of 0.41 (95% confidence interval, 0.20 to 0.87)., Conclusion: Lower erythropoietin responsiveness is a strong, independent predictor of mortality risk and should be considered when evaluating associations between clinical outcomes and potential prognostic indicators, such as Epoetin alfa dose and achieved hemoglobin values.

Despite thymic involution, the number of naive CD4(+) T cells diminishes slowly during aging, suggesting considerable peripheral homeostatic expansion of these cells. To investigate the mechanisms behind, and consequences of, naive CD4+ T cell homeostasis, we evaluated the age-dependent dynamics of the naive CD4+ T cell subsets CD45RA+CD31+ and CD45RA+CD31-. Using both a cross-sectional and longitudinal study design, we measured the relative proportion of both subsets in individuals ranging from 22 to 73 years of age and quantified TCR excision circle content within those subsets as an indicator of proliferative history. Our findings demonstrate that waning thymic output results in a decrease in CD45RA+CD31+ naive CD4+ T cells over time, although we noted considerable individual variability in the kinetics of this change. In contrast, there was no significant decline in the CD45RA+CD31- naive CD4+ T cell subset due to extensive peripheral proliferation. Our longitudinal data are the first to demonstrate that the CD45RA+CD31+CD4+ subset also undergoes some in vivo proliferation without immediate loss of CD31, resulting in an accumulation of CD45RA+CD31+ proliferative offspring. Aging was associated with telomere shortening within both subsets, raising the possibility that accumulation of proliferative offspring contributes to senescence of the naive CD4+ T cell compartment in the elderly. In contrast, we observed retention of clonal TCR diversity despite peripheral expansion, although this analysis did not include individuals over 65 years of age. Our results provide insight into naive CD4+ T cell homeostasis during aging that can be used to better understand the mechanisms that may contribute to immunosenescence within this compartment.

In maintenance hemodialysis (MHD) patients, hepatitis C virus (HCV) infection is common and may be associated with poor clinical outcomes. It was hypothesized that HCV infection would be associated with high all-cause and cardiovascular mortality in these patients after controlling for demographic and clinical characteristics, including surrogates of malnutrition-inflammation complex syndrome. A national database of 13,664 MHD patients who underwent HCV antibody serology testing at least once during a 3-yr interval (July 2001 through June 2004) was analyzed. Measurements included third-generation HCV enzyme immunoassay and routine laboratory measurements. The HCV enzyme immunoassay was reported positive in 1590 (12%) patients. In logistic regression models that included case mix and available surrogates of malnutrition-inflammation complex syndrome, HCV infection was associated with younger age, male gender, black race, Hispanic ethnicity, Medicaid insurance, longer dialysis vintage (duration), unmarried status, HIV infection, and smoking history. In proportional-hazards regressions, the mortality hazard ratio that was associated with HCV infection was 1.25 (95% confidence interval 1.12 to 1.39; P < 0.001). Mortality hazards were higher among incident (dialysis duration <6 mo) than prevalent HD patients. Subgroup analyses indicated that HCV was associated with higher all-cause and cardiovascular mortality across almost all clinical, demographic, and laboratory groups of patients. Hence, in MHD patients, HCV infection exhibits distinct demographic, clinical, and laboratory patterns, including associations with higher dialysis treatment vintage, and is associated with higher mortality. More diligent efforts to prevent and treat HCV infection may improve outcomes in MHD patients.

Despite the enormous cardiovascular disease epidemic among maintenance hemodialysis (MHD) patients, total hypercholesterolemia seems paradoxically to be associated with better survival. It was hypothesized that similar paradoxic associations also exist for serum LDL, HDL, and triglycerides. A 3-yr (July 2001 through June 2004) cohort of 15,859 MHD patients was studied in the United States from DaVita dialysis clinics where lipid profile was measured in at least 50% of all outpatients during a given calendar quarter. Cox proportional hazard models were adjusted for case mix and surrogates of malnutrition-inflammation complex. Both total and LDL hypercholesterolemia showed a paradoxic association with better survival. Hypertriglyceridemia (>200 mg/dl) also showed a similar trend, but serum HDL cholesterol did not have any clear association with survival. The association between a low serum LDL <70 mg/dl, which was prevalent among almost 50% of all MHD patients, and a higher all-cause death risk was robust to multivariate adjustment. In the subgroup analyses, these paradoxic associations persisted among most subgroups, although they tended to be stronger among hypoalbuminemic (<3.8 mg/dl) patients and those with a lower dietary protein intake (<1 g/kg per d). However, in black patients, a high serum LDL (>100 mg/ml) was associated with adjusted cardiovascular death hazard ratio of 1.94 (95% confidence interval 1.12 to 2.38; P = 0.02). Despite inverse associations between hyperlipidemia and survival, black MHD patients with high LDL show almost two-fold increase in cardiovascular death risk. Although these associations may not be causal, they call into question whether specific subgroups of dialysis patients are better targets for cholesterol-lowering therapy.

Background: Decreased dietary protein intake may be associated with increased mortality risk in individuals with kidney failure undergoing maintenance hemodialysis (MHD). We hypothesized that longitudinal changes in dietary protein intake have independent associations with survival in MHD patients., Methods: The relation between urea kinetic-based normalized protein nitrogen appearance (nPNA) and all-cause and cardiovascular mortality was examined in a 2-year (July 2001 to June 2003) cohort of 53,933 MHD patients from virtually all DaVita dialysis clinics in the United States, using both conventional and time-dependent (repeated-measure) Cox models to estimate death hazard ratios for quarterly averaged nPNA categories controlled for case-mix, comorbidity, dialysis dose (Kt/V), and available markers of malnutrition-inflammation complex syndrome (MICS)., Results: The best survival was associated with nPNA between 1.0 and 1.4 g/kg/d, whereas nPNA less than 0.8 or greater than 1.4 g/kg/d was associated with greater mortality in almost all models. Adjustment for MICS mitigated the associations substantially. A decrease in protein intake during the first 6 months in patients with an nPNA in the 0.8- to 1.2-g/kg/d range was associated incrementally with greater death risks in the subsequent 18 months, whereas an increase in nPNA tended to correlate with reduced death risk., Conclusion: Low daily protein intake or decrease in its magnitude over time is associated with increased risk for death in MHD patients. Whether the association between time-varying protein intake and survival is causal or a consequence of anorexia secondary to MICS or other factors needs to be explored further in interventional trials.

Although treating anemia of chronic kidney disease by erythropoiesis-stimulating agents (ESA) may improve survival, most studies have examined associations between baseline hemoglobin values and survival and ignored variations in clinical and laboratory measures over time. It is not clear whether longitudinal changes in hemoglobin or administered ESA have meaningful associations with survival after adjustment for time-varying confounders. With the use of time-dependent Cox regression models, longitudinal associations were examined between survival and quarterly (13-wk averaged) hemoglobin values and administered ESA dose in a 2-yr (July 2001 to June 2003) cohort of 58,058 maintenance hemodialysis patients from a large dialysis organization (DaVita) in the United States. After time-dependent and multivariate adjustment for case mix, quarterly varying administered intravenous iron and ESA doses, iron markers, and nutritional status, hemoglobin levels between 12 and 13 g/dl were associated with the greatest survival. Among prevalent patients, the lower range of the recommended Kidney Disease Quality Outcomes Initiative hemoglobin target (11 to 11.5 g/dl) was associated with a higher death risk compared with the 11.5- to 12-g/dl range. A decrease or increase in hemoglobin over time was associated with higher or lower death risk, respectively, independent of baseline hemoglobin. Administration of any dose of ESA was associated with better survival, whereas among those who received ESA, requiring higher doses were surrogates of higher death risk. In this observational study, greater survival was associated with a baseline hemoglobin between 12 and 13 g/dl, treatment with ESA, and rising hemoglobin. Falling hemoglobin and requiring higher ESA doses were associated with decreased survival. Randomized clinical trials are required to examine these associations.

Background: In maintenance hemodialysis (MHD) outpatients, a reverse epidemiology is described, ie, baseline obesity appears paradoxically associated with improved survival. However, the association between changes in weight over time and prospective mortality is not known., Methods: Using time-dependent Cox models and adjusting for changes in laboratory values over time, the relation of quarterly-varying 3-month averaged body mass index (BMI) to all-cause and cardiovascular mortality was examined in a 2-year cohort of 54,535 MHD patients from virtually all DaVita dialysis clinics in the United States., Results: Patients, aged 61.7 +/- 15.5 (SD) years, included 54% men and 45% with diabetes. Time-dependent unadjusted and multivariate-adjusted models, based on quarterly-averaged BMI controlled for case-mix and available time-varying laboratory surrogates of nutritional status, were calculated in 11 categories of BMI. Obesity, including morbid obesity, was associated with better survival and reduced cardiovascular death, even after accounting for changes in BMI and laboratory values over time. Survival advantages of obesity were maintained for dichotomized BMI cutoff values of 25, 30, and 35 kg/m2 across almost all strata of age, race, sex, dialysis dose, protein intake, and serum albumin level. Examining the regression slope of change in weight over time, progressively worsening weight loss was associated with poor survival, whereas weight gain showed a tendency toward decreased cardiovascular death., Conclusion: Weight gain and both baseline and time-varying obesity may be associated with reduced cardiovascular mortality in MHD patients independent of laboratory surrogates of nutritional status and their changes over time. Morbidly obese patients have the lowest mortality. Clinical trials need to verify these observational findings.

Background: Hypoalbuminaemia is a marker of malnutrition-inflammation complex syndrome (MICS) and a strong predictor of cardiovascular (CV) death in maintenance haemodialysis (MHD) patients. However, serum albumin may change over time. Hence, its time-varying associations with outcome may be different., Methods: Associations between 3-month averaged serum albumin levels, measured in a single laboratory using bromocresol green, and CV mortality were studied longitudinally in a 2-year cohort of 58,058 MHD patients. Mortality predictability of fixed baseline and trimonthly-varying serum albumin concentrations were compared., Results: Hazard ratios (HRs) of CV death strictly increased across decrements of baseline serum albumin, whereas the HR for time-varying serum albumin decrements below 3.8 g/dl did not differ. A drop in serum albumin in the first 6 months was associated with increasing all-cause and CV death risks in the subsequent 18 months, while a rise in serum albumin was a predictor of better survival independent of baseline serum albumin. The multivariate adjusted population-attributable fraction of death due to baseline serum albumin <3.8 g/dl was 19%., Conclusions: Time-varying hypoalbuminaemia predicts all-cause and CV death differently from fixed measures of serum albumin in MHD patients. An increase in serum albumin over time is associated with better survival independent of baseline serum albumin or other MICS surrogates. If this association is causal, an intervention that could increase serum albumin >3.8 g/dl might reduce the number of MHD deaths in the USA by approximately 10,000 annually. Nutritional interventions examining benefits of increasing serum albumin in MHD patients are urgently needed.

The high incidence of cardiac and vascular disease in maintenance hemodialysis (MHD) patients has heightened interest in many investigations concerning the serum lipid levels of these patients. The prevalence and laboratory characteristics of serum lipid concentrations in MHD patients, however, are far from clear. We hypothesized that serum lipids are significantly lower in MHD patients compared to their matched nondialysis counterparts. We compared 2-year averaged serum levels of total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoproteins (HDL), and triglycerides in 285 MHD patients to the same averaged measurements during the same period of time in 285 nondialyzed outpatients from the same geographic area, whose lipid panels were measured in the same laboratory. Matching factors were sex, race and/or ethnicity, diabetes mellitus, and age (+/- 5 years). The MHD patients and their matched controls were 55.6 +/- 13.5 (SD) and 56.3 +/- 13.0 years old, respectively. Each group contained 51% women, 31% African Americans, 52% Hispanics, and 37% diabetics; 16% of MHD patients and 38% of controls were receiving statins. Body mass index (BMI) was significantly lower in MHD patients than in controls (26.2 vs. 31.5 kg/m2; p < 0.001). Serum cholesterol levels were significantly lower in MHD patients than in control subjects including after adjustment for BMI and statin use (TC, -51; LDL, -39; and HDL, -10 mg/dL; p < 0.001). Using conditional logistic regression for matched data and after controlling for BMI and statins, all odds ratios for predetermined hypercholesterolemic, but not hypertriglyceridemic, levels were significantly and substantially lower than 1.00, indicating much lower likelihood of hypercholesterolemia in MHD patients. Total and LDL hypercholesterolemia, although very common in nondialysis ambulatory outpatients, are substantially less prevalent in the MHD population, whereas hypertriglyceridemia is approximately equally prevalent between these populations.

Maintenance hemodialysis patients in the United States have a high prevalence (approximately 80%) of systolic hypertension and a high mortality (approximately 20% per year). Some reports indicate a paradoxical association between hypertension and mortality in hemodialysis patients (ie, a normal to low blood pressure is associated with poor outcome), whereas high pressure confers survival advantages, a phenomenon referred to as "reverse epidemiology." We hypothesized that malnutrition-inflammation complex syndrome may be a cause of this paradoxical association. We studied a 15-month cohort of 40 933 hemodialysis patients in the United States whose predialysis and postdialysis blood pressure values were recorded routinely during each hemodialysis treatment. Patients were 59.8+/-15.3 years old; 54% were women and 46% diabetics. Cox proportional hazard models were used for blood pressure categories (systolic <110, > or =190 mm Hg; diastolic <50, > or =110; and increments of 10 mm Hg in between). Unadjusted, case-mix and dialysis dose-adjusted, and additional malnutrition-inflammation-adjusted hazard ratios of all-cause and cardiovascular death showed progressively increasing all-cause and cardiovascular death risk for decreasing blood pressure values. The lowest mortality was associated with predialysis systolic pressure of 160 to 189 mm Hg, whereas normal to low predialysis pressure values were associated with significantly increased mortality. Adjustment for the malnutrition-inflammation mitigated only a small portion of paradoxical associations between the low blood pressure and mortality. Predialysis systolic hypertension remained a significant predictor of highest all-cause and cardiovascular survival rate. Although these associations may not be causal, they call into question whether treatment goals for the general population can be applied to dialysis patients or other similar populations.

In the general population, a high body mass index (BMI; in kg/m(2)) is associated with increased cardiovascular disease and all-cause mortality. However, the effect of overweight (BMI: 25-30) or obesity (BMI: >30) in patients with chronic kidney disease (CKD) undergoing maintenance hemodialysis (MHD) is paradoxically in the opposite direction; ie, a high BMI is associated with improved survival. Although this "reverse epidemiology" of obesity or dialysis-risk-paradox is relatively consistent in MHD patients, studies in CKD patients undergoing peritoneal dialysis have yielded mixed results. Growing confusion has developed among physicians, some of whom are no longer confident about whether to treat obesity in CKD patients. A similar reverse epidemiology of obesity has been described in geriatric populations and in patients with chronic heart failure (CHF). Possible causes of the reverse epidemiology of obesity include a more stable hemodynamic status, alterations in circulating cytokines, unique neurohormonal constellations, endotoxin-lipoprotein interaction, reverse causation, survival bias, time discrepancies among competitive risk factors, and malnutrition-inflammation complex syndrome. Reverse epidemiology may have significant clinical implications in the management of dialysis, CHF, and geriatric patients, ie, populations with extraordinarily high mortality. Exploring the causes and consequences of the reverse epidemiology of obesity in dialysis patients can enhance our insights into similar paradoxes observed for other conventional risk factors, such as blood pressure and serum cholesterol and homocysteine concentrations, and in other populations such as those with CHF, advanced age, cancer, or AIDS. Weight-gaining interventional studies in dialysis patients are urgently needed to ascertain whether they can improve survival and quality of life.

In maintenance hemodialysis (MHD) patients, associations between demographic, clinical and laboratory values and mortality, including cardiovascular death, are significantly different and, in some cases, in the opposite direction of those derived from the general population. This phenomenon, termed 'reverse epidemiology', is not limited to MHD patients but is also observed in populations that encompass an estimated 20 million Americans including those with an advanced age, heart failure, malignancies, and AIDS. A significant portion of this reversal may be due to the overwhelming effect of the malnutrition-inflammation complex syndrome (MICS). Since two thirds of MHD patients die within 5 years of initiation of dialysis treatment, traditional cardiovascular risk factors such as obesity, hypercholesterolemia and hypertension cannot exert a long-term deleterious impact, and instead, their short-term beneficial effects on MICS provides a survival advantage. In order to improve survival and quality of life in MHD patients, extrapolated ideal norms derived from the general population should be substituted with novel norms obtained from outcome-oriented epidemiologic analyses while accounting for the differential effect of MICS in different case-mix subgroups., (Copyright 2005 S. Karger AG, Basel.)