Antiretroviral therapy initiation is not associated with risky sexual behavior among heterosexual HIV-infected persons in serodiscordant partnerships

Abstract

Background— Few prospective studies have assessed whether antiretroviral therapy (ART) use is associated with changes in sexual risk behavior of HIV-infected persons in known HIV- serodiscordant partnerships. Methods— We conducted a longitudinal analysis of HIV-infected persons with known uninfected partners enrolled in the Partners PrEP Study in Kenya and Uganda. ART use and self-reported sexual behavior were ascertained every 3 months. We assessed the effect of ART on sexual risk behaviors using zero-inflated negative binomial regression. Primary outcomes were condomless vaginal sex acts, pregnancy incidence and new STI diagnoses. Results— We followed 1817 HIV-infected persons (58% women) for 864 person-years before ART initiation and 771 person-years after ART. Median CD4 and plasma viral load at ART initiation were 277 cells/μL and 4.18 log 10 copies/mL. ART use was associated with a significant decrease in condomless vaginal sex acts with HIV-uninfected partners (0.65 vs. 0.39 per month; rate ratio [RR] 0.64; 95% CI: 0.55–0.75; p<0.001), but not condomless vaginal sex acts with non- primary partners (1.30 vs. 1.04 per month; RR 0.94; 95% CI: 0.94–1.20; p=0.62). Pregnancy incidence was lower after ART (13.2 vs 8.4 per 100 person-years; HR 0.71, 95% CI: 0.60–0.84, p<0.001). Incident STI diagnoses were similar (OR 1.05, 95% CI: 0.86–1.29; p=0.63). Conclusions— Substantial risk compensation did not occur following ART initiation among East African HIV-infected persons with known HIV-uninfected partners. These data inform modeling studies of ART for HIV prevention by suggesting that risky sexual behavior did not appear to offset decreased HIV infectiousness in this key population