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338 results on '"Wejnert, Cyprian"'

4. Estimating the impact of HIV PrEP regimens containing long-acting injectable cabotegravir or daily oral tenofovir disoproxil fumarate/emtricitabine among men who have sex with men in the United States: a mathematical modelling study for HPTN 083

Author

Mitchell, Kate M., Boily, Marie-Claude, Hanscom, Brett, Moore, Mia, Todd, Jeffery, Paz-Bailey, Gabriela, Wejnert, Cyprian, Liu, Albert, Donnell, Deborah J., Grinsztejn, Beatriz, Landovitz, Raphael J., and Dimitrov, Dobromir T.

Published
2023
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8. Evaluating Variance Estimators for Respondent-Driven Sampling.

Author

Spiller, Michael W, Gile, Krista J, Handcock, Mark S, Mar, Corinne M, and Wejnert, Cyprian

Subjects
Mathematical Sciences, Statistics
Abstract

Respondent-Driven Sampling (RDS) is a network-based method for sampling hard-to-reach populations that is widely used by public health agencies and researchers worldwide. Estimation of population characteristics from RDS data is challenging due to the unobserved population network, and multiple point and variance estimators have been proposed. Research evaluating these estimators has been limited and largely focused on point estimation; this analysis is the first evaluation of multiple variance estimators currently in use. We evaluated the performance of RDS variance estimators via simulations of RDS on synthetic networked populations constructed from 40 RDS surveys of injection drug users in the United States. In these simulations, average design effects (DEs) were lower and average 95% confidence interval (CI) coverage percentages were higher than suggested in previous work: typical DE range=1-3; average 95% CI coverage=93%. However, DE and CI coverage vary across the 40 sets of simulations, suggesting that the characteristics of a given study should be evaluated to assess estimator performance. We also found that simulation results are sensitive to whether sampling is conducted with replacement and the approach used to create CIs. We conclude that CI coverage rates and DEs are often acceptable but not perfect and that RDS estimates are usually reliable in scenarios where RDS assumptions are met. While RDS estimation performed reasonably well, we found strong evidence that the simple random sample variance estimator and corresponding CIs significantly underestimate variance and should not be used to analyze RDS data.

Published
2018

11. An application of agent-based modeling to explore the impact of decreasing incarceration rates and increasing drug treatment access on sero-discordant partnerships among people who inject drugs

Author

Linton, Sabriya L., Jarlais, Don C. Des, Ornstein, Joseph T., Kasman, Matt, Hammond, Ross, Kianian, Behzad, Smith, Justin C., Wolfe, Mary E, Ross, Zev, German, Danielle, Flynn, Colin, Raymond, Henry F., Klevens, R. Monina, Spencer, Emma, Schacht, John-Mark, Finlayson, Teresa, Paz-Bailey, Gabriela, Wejnert, Cyprian, and Cooper, Hannah L.F.

Published
2021
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12. Intersecting Structural and Psychosocial Conditions: Investigating Injection Drug Use and HIV Among Transgender Women.

Author

Burnett, Janet, Olansky, Evelyn, Baugher, Amy R., Lee, Kathryn, Callens, Steven, Wejnert, Cyprian, Wortley, Pascale, Mustaafaa, Genetha, Taylor, Brittany, Sey, Ekow Kwa, Olaes, Gia, Ma, Yingbo, Robinson, William T., Barak, Narquis, Davis, Jasmine, Braunstein, Sarah, Rivera, Alexis, Lopez, Jasmine, Brady, Kathleen A., and Nassau, Tanner

Published
2025
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24. Analysis of a capture-recapture estimator for the size of populations with heterogenous catchability, and its evaluation on RDS data from rural Uganda

Author

Berchenko, Yakir, White, Richard G., Wejnert, Cyprian, and Frost, Simon D. W.

Subjects
Statistics - Applications, Quantitative Biology - Quantitative Methods, Statistics - Methodology
Abstract

In this paper, we consider capture-recapture experiments with heterogenous catchability. In the setting we consider, the widespread Huggins-Alho estimator is not very suitable and we introduce and study a new generalized Horvitz-Thompson estimator. Our motivation is Respondent Driven Sampling (RDS), a prime example for such a setting where the capture probability is dependent on both the unknown population size as well as on an observable covariate, the network degree of an individual, due to peer recruitment. After discussing the theoretical properties of the new estimator, with full details given in the appendix, we evaluate it on various empirical and simulated data-sets, focusing on an RDS survey in a population in rural Uganda in which the population size is known a priori. The results thus obtained demonstrate that the adjusted estimator is less biased than the naive Lincoln-Petersen estimator., Comment: 22 pages, 6 figures

Published
2011

26. Identifying Which Place Characteristics are Associated with the Odds of Recent HIV Testing in a Large Sample of People Who Inject Drugs in 19 US Metropolitan Areas

Author

Tempalski, Barbara, Cooper, Hannah L. F., Kelley, Mary E., Linton, Sabriya L., Wolfe, Mary E., Chen, Yen-Tyng, Ross, Zev, Des Jarlais, Don C., Friedman, Samuel R., Williams, Leslie D., Semaan, Salaam, DiNenno, Elizabeth, Wejnert, Cyprian, Broz, Dita, Paz-Bailey, Gabriela, and for the National HIV Behavioral Surveillance Study Group

Published
2019
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30. Pre-exposure Prophylaxis Use and Detected Sexually Transmitted Infections Among Men Who Have Sex With Men in the United States—National HIV Behavioral Surveillance, 5 US Cities, 2017

Author

Chapin-Bardales, Johanna, Johnson Jones, Michelle L., Kirkcaldy, Robert D., Bernstein, Kyle T., Paz-Bailey, Gabriela, Phillips, Christi, Papp, John R., Raymond, Henry F., Opoku, Jenevieve, Braunstein, Sarah L., Spencer, Emma C., Khuwaja, Salma, and Wejnert, Cyprian

Published
2020
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33. Associations of place characteristics with HIV and HCV risk behaviors among racial/ethnic groups of people who inject drugs in the United States

Author

Taussig, Jennifer, Johnson, Shacara, Todd, Jeff, Flynn, Colin, German, Danielle, Isenberg, Debbie, Driscoll, Maura, Hurwitz, Elizabeth, Prachand, Nikhil, Benbow, Nanette, Melville, Sharon, Yeager, Richard, Dyer, Jim, Novoa, Alicia, Thrun, Mark, Al-Tayyib, Alia, Higgins, Emily, Mokotoff, Eve, Griffin, Vivian, Sayegh, Aaron, Risser, Jan, Rehman, Hafeez, Bingham, Trista, Sey, Ekow Kwa, Metsch, Lisa, Forrest, David, Beck, Dano, Cardenas, Gabriel, Nemeth, Chris, Smith, Lou, Watson, Carol-Ann, Robinson, William T., Gruber, DeAnn, Barak, Narquis, Neaigus, Alan, Jenness, Samuel, Wendel, Travis, Gelpi-Acosta, Camila, Hagan, Holly, Godette, Henry, Bolden, Barbara, D'Errico, Sally, Brady, Kathleen A., Kirkland, Althea, Shpaner, Mark, Miguelino-Keasling, Vanessa, Velasco, Al, Raymond, H. Fisher, De Leo'n, Sandra Miranda, Rolo'n-Colo'n, Yadira, Courogen, Maria, Thiede, Hanne, Burt, Richard, Herbert, Michael, Friedberg, Yelena, Wrigley, Dale, Fisher, Jacob, Sansone, Marie, West-Ojo, Tiffany, Magnus, Manya, Kuo, Irene, Linton, Sabriya L., Cooper, Hannah L.F., Kelley, Mary E., Karnes, Conny C., Ross, Zev, Wolfe, Mary E., Chen, Yen-Tyng, Friedman, Samuel R., Des Jarlais, Don, Semaan, Salaam, Tempalski, Barbara, Sionean, Catlainn, DiNenno, Elizabeth, Wejnert, Cyprian, and Paz-Bailey, Gabriela

Published
2016
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37. Factors Associated with Use of HIV Prevention and Health Care Among Transgender Women--Seven Urban Areas, 2019-2020

Author

Lee, Kathryn, Trujillo, Lindsay, Olansky, Evelyn, Robbins, Taylor, Agnew-Brune, Christine, Morris, Elana, Finlayson, Teresa, Kanny, Dafna, and Wejnert, Cyprian

Subjects
HIV (Viruses) -- Care and treatment, Women -- Health aspects, HIV testing -- Usage, Homelessness -- Usage -- Surveys, Transgender people -- Surveys, Sexually transmitted diseases -- Prevention, Metropolitan areas -- Surveys -- Usage, Health
Abstract

Transgender women * are disproportionately affected by HIV. Among 1,608 transgender women who participated in CDC's National HIV Behavioral Surveillance (NHBS) during 2019-2020, 42% received a positive HIV test result [...]

Published
2022

39. Overview and Methodology of the National HIV Behavioral Surveillance Among Transgender Women -- Seven Urban Areas, United States, 2019-2020.

Author

Kanny, Dafna, Lee, Kathryn, Olansky, Evelyn, Robbins, Taylor, Trujillo, Lindsay, Finlayson, Teresa, Morris, Elana, Agnew-Brune, Christine, Cha, Susan, Chapin-Bardales, Johanna, and Wejnert, Cyprian

Subjects
TRANS women, HIV, WOMEN of color, SEXUAL assault
Abstract

Transgender women, especially transgender women of color, are disproportionately affected by HIV. However, no surveillance system collects data on HIV risk factors among this population. To address this gap, CDC developed a surveillance system entitled National HIV Behavioral Surveillance Among Transgender Women (NHBS-Trans) to assess behavioral and contextual data through systematic biobehavioral surveillance to monitor behavioral risk factors, prevention usage, and HIV prevalence among transgender women. NHBS-Trans used respondent-driven sampling in seven urban areas in the United States. Trained interviewers used a standardized, anonymous questionnaire to collect information on HIV-related behavioral risk factors, HIV testing, and use of prevention services. Each of the seven participating project areas recruited approximately 200 eligible transgender women and offered anonymous HIV testing. Overall, in the seven project areas, 1,757 participants completed the eligibility screener for NHBS-Trans during 2019-2020; of these, 6.6% were seeds (i.e., a limited number of initial participants who were chosen by referrals from persons and community-based organizations who knew or were part of the local population of transgender women). A total of 1,637 (93.2%) participants were eligible, consented, and completed the interview. Of these, 1,624 (99.2%) agreed to HIV testing. Of the total 1,637 participants, 29 participants did not report identity of woman or transgender woman, resulting in a final sample of 1,608 transgender women. NHBS-Trans project area staff members (n = 14) reported that the survey was timely and addressed a critical need for HIV surveillance in a population that is often overlooked. The MMWR supplement includes this overview report on NHBS-Trans, which describes the methods (history, participant eligibility criteria, questionnaire, data collection, and HIV testing) as well as evaluation of project implementation and the performance of the questionnaire content, specifically the acceptability for transgender women. The other NHBS-Trans reports in the supplement include information on pre-exposure prophylaxis use, psychosocial syndemic conditions and condomless anal intercourse, nonprescription hormone use, homelessness, discrimination and the association between employment discrimination and health care access and use, and social support and the association between certain types of violence and harassment (gender-based verbal and physical abuse or harassment, physical intimate partner abuse or harassment, and sexual violence) and suicidal ideation. NHBS-Trans provides important data related to the goals of the Ending the HIV Epidemic in the U.S. initiative. Findings from NHBS-Trans can help guide community leaders, clinicians, and public health officials in improving access to and use of HIV prevention and treatment services by transgender women. [ABSTRACT FROM AUTHOR]

Published
2024
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40. Structural and Psychosocial Syndemic Conditions and Condomless Anal Intercourse Among Transgender Women -- National HIV Behavioral Surveillance Among Transgender Women, Seven Urban Areas, United States, 2019-2020.

Author

Hershow, Rebecca B., Trujillo, Lindsay, Olansky, Evelyn, Lee, Kathryn, Agnew-Brune, Christine, Wejnert, Cyprian, and Adams, Monica

Subjects
UNSAFE sex, ANAL sex, TRANS women, HIV infection transmission, SEXUAL assault
Abstract

Psychosocial and structural syndemic conditions, including polydrug use and experiencing homelessness, frequently co-occur and might jointly increase HIV risk. Limited studies have assessed racial and ethnic differences in exposure to syndemic conditions and behaviors associated with HIV transmission among transgender women. This report examines the relation between syndemic conditions and condomless anal intercourse (CAI) among transgender women in seven urban areas in the United States to develop HIV prevention interventions for transgender women. During 2019-2020, transgender women in seven urban areas were recruited using respondent-driven sampling for a biobehavioral survey. Reported syndemic conditions (psychosocial: polydrug use, sexual violence, and psychological distress; structural: homelessness, incarceration, and exchange sex) were summed to create a syndemic score. Using modified Poisson regression to account for RDS, the study assessed whether the strength of the association between syndemic score and CAI differed by race and ethnicity. To assess additive interaction, the relative excess prevalence owing to interaction (REPI) and 95% CIs for selected pairs of syndemic conditions on CAI prevalence stratified by race and ethnicity were estimated. Of 1,348 transgender women (Black = 546, White = 176, and Hispanic = 626), 55% reported CAI; and 24% reported =3 syndemic conditions. Reporting additional syndemic conditions was associated with CAI for White, Hispanic, and Black participants. The association was significantly stronger for White than Black and Hispanic participants. Limited significant superadditive interactions were found, although the majority were between structural syndemic conditions. Racial and ethnic differences in REPI estimates were observed. Reporting more syndemic conditions was associated with increased CAI across racial and ethnic groups, demonstrating that HIV prevention efforts for transgender women should address structural and psychosocial syndemic conditions. Results differed by race and ethnicity, indicating that syndemic-focused interventions for transgender women should be tailored to racial and ethnic groups. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Sex Practices by HIV Awareness and Engagement in the Continuum of Care Among MSM: A National HIV Behavioral Surveillance Analysis in 21 U.S. Cities

Author

Whitham, Hilary K., Sansom, Stephanie L., Wejnert, Cyprian, Finlayson, Teresa, Huang, Ya-lin A., An, Qian, Paz-Bailey, Gabriela, Taussig, Jennifer, Gern, Robert, Hoyte, Tamika, Salazar, Laura, White, Jianglan, Todd, Jeff, Bautista, Greg, Flynn, Colin, Sifakis, Frangiscos, German, Danielle, Isenberg, Debbie, Driscoll, Maura, Hurwitz, Elizabeth, Miminos, Maura, Doherty, Rose, Wittke, Chris, Prachand, Nikhil, Benbow, Nanette, Melville, Sharon, Pannala, Praveen, Yeager, Richard, Sayegh, Aaron, Dyer, Jim, Sheu, Shane, Novoa, Alicia, Thrun, Mark, Al-Tayyib, Alia, Wilmoth, Ralph, Higgins, Emily, Griffin, Vivian, Mokotoff, Eve, MacMaster, Karen, Wolverton, Marcia, Risser, Jan, Rehman, Hafeez, Padgett, Paige, Bingham, Trista, Sey, Ekow Kwa, LaLota, Marlene, Metsch, Lisa, Forrest, David, Beck, Dano, Cardenas, Gabriel, Nemeth, Chris, Anderson, Bridget J., Watson, Carol-Ann, Smith, Lou, Robinson, William T., Gruber, DeAnn, Barak, Narquis, Murrill, Chris, Neaigus, Alan, Jenness, Samuel, Hagan, Holly, Reilly, Kathleen H., Wendel, Travis, Cross, Helene, Bolden, Barbara, D’Errico, Sally, Wogayehu, Afework, Godette, Henry, Brady, Kathleen A., Kirkland, Althea, Sifferman, Andrea, Miguelino-Keasling, Vanessa, Velasco, Al, Tovar, Veronica, Raymond, H. Fisher, De León, Sandra Miranda, Rolón-Colón, Yadira, Marzan, Melissa, Courogen, Maria, Jaenicke, Tom, Thiede, Hanne, Burt, Richard, Jia, Yujiang, Opoku, Jenevieve, Sansone, Marie, West, Tiffany, Magnus, Manya, Kuo, Irene, Behavioral Surveillance Team, and for the NHBS Study Group

Published
2017
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46. Racial, Ethnic, and Gender Disparities in Awareness of Preexposure Prophylaxis Among HIV-Negative Heterosexually Active Adults at Increased Risk for HIV Infection--23 Urban Areas, United States, 2019

Author

Baugher, Amy R., Trujillo, Lindsay, Kanny, Dafna, Freeman, Jincong Q., Hickey, Terence, Sionean, Catlainn, Respress, Ebony, Bardales, Johanna Chapin, Marcus, Ruthanne, Finlayson, Teresa, and Wejnert, Cyprian

Subjects
United States. Department of Health and Human Services, HIV (Viruses) -- Risk factors, Adults -- Health aspects, HIV infection -- Risk factors, Health
Abstract

In 2019, heterosexual sex accounted for 23% of new HIV diagnoses in the United States and six dependent areas (1). Although preexposure prophylaxis (PrEP) can safely reduce the risk for [...]

Published
2021

49. Respondent-Driven Sampling with Hard-to-Reach Emerging Adults: An Introduction and Case Study with Rural African Americans

Author

Kogan, Steven M., Wejnert, Cyprian, and Chen, Yi-fu

Abstract

Obtaining representative samples from populations of emerging adults who do not attend college is challenging for researchers. This article introduces respondent-driven sampling (RDS), a method for obtaining representative samples of hard-to-reach but socially interconnected populations. RDS combines a prescribed method for chain referral with a mathematical model to adjust for potential sampling bias. A case study is presented of the use of RDS to obtain a sample of rural African American emerging adults and to document the feasibility, effectiveness, and efficiency of the method with this population. RDS-related findings indicate that rural African American emerging adults form interconnected social networks that are appropriate for using RDS. RDS procedures are an acceptable and relatively efficient strategy for rural African Americans that is likely to yield more representative samples than traditional snowball sampling and provides data on potential sampling biases for planning multivariate analyses. (Contains 2 tables and 3 figures.)

Published
2011
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50. HIV Infection and HIV-Associated Behaviors Among Persons Who Inject Drugs--23 Metropolitan Statistical Areas, United States, 2018

Author

Handanagic, Senad, Finlayson, Teresa, Burnett, Janet C., Broz, Dita, and Wejnert, Cyprian

Subjects
HIV (Viruses) -- Behavior, HIV testing, Drugs, HIV infection, Health
Abstract

In the United States, 10% of HIV infections diagnosed in 2018 were attributed to unsafe injection drug use or male-to-male sexual contact among persons who inject drugs (PWID) (1). In [...]

Published
2021

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