Impact of early antiretroviral treatment on sexual behaviour in the INSIGHT Strategic Timing of Anti-Retroviral Treatment (START) Trial.

Abstract

BACKGROUND\nAntiretroviral treatment (ART) reduces HIV infectiousness, but the effect of early ART on sexual behaviour is unclear.\n\n\nMETHODS\nWe assessed, within the START randomised trial that enrolled HIV-positive adults with CD4>500/mm, the effect of early (immediate) versus deferred ART on: (i) condomless sex with HIV-serodifferent partners (CLS-D); (ii) all condomless sex (CLS); (iii) HIV transmission-risk-sex (CLS-D-HIV-risk, defined as CLS-D and: not on ART or started ART\u200a<\u200a6 months ago or viral load(VL)>200c/mL or no VL in past 6 months), during two year follow-up. Month-12 CLS-D (2010-2014) was the primary outcome.\n\n\nRESULTS\nAmong 2562 MSM, there was no difference between immediate and deferred arms in CLS-D at month 12 [12.6% versus 13.1%; difference (95% CI): -0.4% (-3.1%, 2.2%), p\u200a=\u200a0.75] or month 24, or in CLS. Among 2010 heterosexual men and women, CLS-D at month 12 tended to be higher in the immediate versus deferred arm [10.8% versus 8.3%; difference:2.5% (-0.1%, 5.2%), p\u200a=\u200a0.062]; the difference was greater at month 24 [9.3% versus 5.6%; difference:3.7%(1.0%, 6.4%), p\u200a=\u200a0.007], at which time CLS was higher in the immediate arm [20.7% versus 15.7%, p\u200a=\u200a0.013]. CLS-D-HIV-risk at month 12 was substantially lower in the immediate versus deferred arm for MSM [0.2% versus 11.0%; difference: -10.7% (-12.5%, -8.9%), p\u200a<\u200a0.001] and heterosexuals [0.6% versus 7.7%; difference: -7.0% (-8.8%, -5.3%), p\u200a<\u200a0.001], due to viral suppression on ART.\n\n\nCONCLUSIONS\nA strategy of early ART had no effect on condomless sex with HIV-serodifferent partners among MSM, but resulted in modestly higher prevalence among heterosexuals. However, among MSM and heterosexuals, early ART resulted in a substantial reduction in HIV-transmission-risk-sex, to a very low absolute level.