CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

855 CHANGES IN RISK BEHAVIORS AFTER HIV SEROCONVERSION, BANGKOK MSM COHORT STUDY Wipas Wimonsate 1 , Sarika Pattanasin 1 , Pikunchai Luechai 1 , Jaray Tongtoyai 1 , Wichuda Sukwicha 1 , Chaiwat Ungsedhapand 1 , Anupong Chitwarakorn 2 , Michael Thigpen 3 , Eileen Dunne 3 , Timothy Holtz 3 1 Thailand Ministry of Pub Hlth–US CDC Collab, Nonthaburi, Thailand, 2 Thailand Ministry of Pub Hlth, Nonthaburi, Thailand, 3 US CDC, Nonthaburi, Thailand Background: HIV seroconversion has been associated with change in HIV risk behaviors among men who have sex with men (MSM). We evaluated risk behaviors before and after HIV seroconversion in the Bangkok MSM cohort study (BMCS). Methods: From 2006–2016, we enrolled Bangkok MSM aged ≥18 years into BMCS and followed them at 4-month intervals. At each visit, participants provided behavioral information using computer-assisted self-interview and were tested for HIV on oral fluid, and, if reactive, confirmed with three rapid tests on serum. We used the McNemar test to compare proportions of each risk behavior reported at the study visit immediately before seroconversion with the visit immediately after seroconversion, and with the visit at 12 months after seroconversion. We compared these behaviors between the visit immediately after seroconversion with the visit at 12 months after seroconversion. We used the binomial distribution to calculate the estimates of the percentage reduction in risk behaviors with associated 95% confidence intervals [CI]. Results: Among 1744 enrollees, 1259 (72.2%) were initially HIV-negative and returned for at least one follow-up visit: 249 (19.8%) individuals acquired HIV during the follow-up period. Among 183 who returned for follow-up both immediately before and after seroconversion and provided information for the comparison of behaviors, there was a 64% reduction in group sex after seroconversion (95% CI 0.50-0.76), an 82% reduction in condomless anal intercourse (CAI) with a steady male partner (95% CI 0.71-0.90), and a 79% reduction in CAI with a casual partner (95% CI 0.66-0.88). Among 150 who were available at visits pre-seroconversion and 12-month after seroconversion, there was a 74% reduction in group sex at 12-month after seroconversion (95% CI 0.59-0.85), an 84% reduction in CAI with a steady male partner (95% CI 0.72-0.93), and an 82% reduction in CAI with a casual partner (95% CI 0.68-0.92). Among 158 who were available at visits immediately post-seroconversion and 12-month after seroconversion, there were no significant differences in the proportions with these behaviors. There were no significant changes in recreational drug use and erectile dysfunctional drug use before and after seroconversion. Conclusion: In this cohort, three high-risk sexual behaviors decreased in frequency for at least 12 months after HIV seroconversion. This change in behaviors could prevent further onward transmission of HIV, especially during the critical period after HIV acquisition. 856 AN EMPIRIC RISK SCORE TO GUIDE PREP UPTAKE IN MSM IN COASTAL KENYA Elizabeth Wahome 1 , Alexander N. Thiong’o 1 , Oscar Chirro 1 , Evans Gichuru 1 , John Mwambi 1 , Matt A. Price 2 , Susan M. Graham 3 , Eduard Sanders 4 1 KEMRI Wellcome Trust Rsr Prog, Kilifi, Kenya, 2 Intl AIDS Vaccine Initiative, New York, NY, USA, 3 Univ of Washington, Seattle, WA, USA, 4 Kenya Med Rsr Inst, Kilifi, Kenya Background: The World Health Organization recommends preexposure prophylaxis (PrEP) for populations with high HIV-1 incidence (≥3% per year). While Kenyan guidelines recommend PrEP for men who have sex with men (MSM), HIV-1 acquisition risk is heterogeneous. We set out to develop an empiric risk score to target PrEP use among MSM in Kenya, using data from a cohort of high-risk MSM followed on the Kenyan coast. Methods: Poisson regression was used to identify predictors of incident HIV-1 infection in MSM followed in the period 2005-2016 in Coastal Kenya. We assigned a predictor score to each statistically significant predictor based on its model coefficient, summing predictor scores to calculate a risk score for each participant. We then determined which risk score cut-off would correspond to an HIV-1 incidence ≥3%. We evaluated risk score algorithm performance, and assessed whether higher risk scores correlated with higher HIV-1 incidence. We then calculated the proportion of MSM who should start PrEP, if this algorithmwas used. Results: A total of 741 MSM contributed a median follow-up time of 15.0 (interquartile range: 5.6-33.1) months, for an average of 117 MSM followed per calendar year (range: 11-208). HIV-1 incidence was 7.0 [95% confidence interval (CI), 5.7–8.5] per 100 person-years. Independent predictors of HIV-1 infection and corresponding risk scores were: 1 for exclusive sex with men, receptive anal intercourse, any unprotected sex, and group sex; and 2 for age 18-24 years. While laboratory-confirmed urethral or rectal gonorrhea infection was the strongest predictor of HIV-1 infection, we did not include this in the model as few providers have access to such information. The area under the receiver operator curve (AUC) for predictive ability of the risk score was 0.71 (95% CI, 0.66-0.76). A risk score ≥1 corresponded to an HIV-1 incidence ≥3% (Table). A unit increase in risk score strongly correlated with an increase in observed HIV-1 incidence (test for trend: p<0.001). A total of 79.6% of MSM participating in this cohort met eligibility criteria for PrEP start. Conclusion: An empiric risk score based on the summation of four reported risk behaviors and age strongly correlated with increased HIV-1 incidence in our cohort. This risk score may help Kenyan health providers to assess HIV-1 acquisition risk in MSM and encourage PrEP uptake. MSM with recent laboratory-confirmed gonorrhea infection qualify for PrEP a priori but should be evaluated for acute HIV infection prior to initiation.

Poster and Themed Discussion Abstracts

CROI 2017 370