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Background: Population-level estimates of sexual network mixing for parameterizing prediction models of pre-exposure prophylaxis (PrEP) effectiveness are needed to inform prevention of HIV transmission among men who have sex with men (MSM). Estimates obtained by egocentric sampling are vulnerable to information bias due to incomplete respondent knowledge.Methods: We estimated patterns of serosorting and PrEP sorting among MSM in the United States using data from a 2017-2019 egocentric sexual network study. Respondents served as proxies to report the HIV status and PrEP use of recent sexual partners. We contrasted results from a complete-case analysis (unknown HIV and PrEP excluded) versus a bias analysis with respondent-reported data stochastically reclassified to simulate unobserved self-reported data from sexual partners.Results: We found strong evidence of preferential partnering across analytical approaches. The bias analysis showed concordance between sexual partners of HIV diagnosis and PrEP use statuses for MSM with diagnosed HIV (39%; 95% simulation interval: 31, 46), MSM who used PrEP (32%; 21, 37), and MSM who did not use PrEP (83%; 79, 87). The fraction of partners with diagnosed HIV was higher among MSM who used PrEP (11%; 9, 14) compared with MSM who did not use PrEP (4%; 3, 5). Comparatively, across all strata of respondents, the complete-case analysis overestimated the fractions of partners with diagnosed HIV or PrEP use.Conclusions: We found evidence consistent with HIV and PrEP sorting among MSM, which may decrease the population-level effectiveness of PrEP. Bias analyses can improve mixing estimates for parameterization of transmission models. [ABSTRACT FROM AUTHOR]

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Amphetamine use is higher among men who have sex with men (MSM) compared with other men, and is associated with sexual behavior linked to HIV transmission. No national estimates of amphetamine use among MSM with HIV have been published. We used data from the Medical Monitoring Project, a nationally representative sample of persons with diagnosed HIV, to describe patterns in amphetamine use in the past 12 months among MSM during 2015–2016 (N = 3796). Prevalence of amphetamine use in this population was 9.6% (95% CI 7.6, 11.6%) in the past 12 months. MSM who used amphetamines were more likely to have condomless sex with partners without HIV or of unknown serostatus (PR 1.87; 95% CI 1.62, 2.16) and less likely to be durably virally suppressed (PR 0.81; 95% CI 0.71, 0.91). Interventions to address amphetamine use and associated transmission risk behaviors among MSM living with HIV may decrease transmission. [ABSTRACT FROM AUTHOR]

The potential for human immunodeficiency virus (HIV) preexposure prophylaxis (PrEP) to reduce the racial disparities in HIV incidence in the United States might be limited by racial gaps in PrEP care. We used a network-based mathematical model of HIV transmission for younger black and white men who have sex with men (BMSM and WMSM) in the Atlanta, Georgia, area to evaluate how race-stratified transitions through the PrEP care continuum from initiation to adherence and retention could affect HIV incidence overall and disparities in incidence between races, using current empirical estimates of BMSM continuum parameters. Relative to a no-PrEP scenario, implementing PrEP according to observed BMSM parameters was projected to yield a 23% decline in HIV incidence (hazard ratio = 0.77) among BMSM at year 10. The racial disparity in incidence in this observed scenario was 4.95 per 100 person-years at risk (PYAR), a 19% decline from the 6.08 per 100 PYAR disparity in the no-PrEP scenario. If BMSM parameters were increased to WMSM values, incidence would decline by 47% (hazard ratio = 0.53), with an associated disparity of 3.30 per 100 PYAR (a 46% decline in the disparity). PrEP could simultaneously lower HIV incidence overall and reduce racial disparities despite current gaps in PrEP care. Interventions addressing these gaps will be needed to substantially decrease disparities. [ABSTRACT FROM AUTHOR]