Effect of early antiretroviral therapy on sexual behaviors and HIV-1 transmission risk among adults with diverse heterosexual partnership statuses in Côte d'Ivoire

Abstract

Background: The effect of early initiation of antiretroviral therapy (ART; ie, at CD4(+) T-cell counts >350 cells/mm(3)) on sexual behaviors and human immunodeficiency virus type 1 (HIV) transmission risk has not been documented in populations other than HIV-serodiscordant couples in stable relationships.

Methods: On the basis of data from a behavioral study nested in a randomized, controlled trial (Temprano-ANRS12136) of early ART, we compared proportions of risky sex (ie, unprotected sex with a partner of negative/unknown HIV status) reported 12 months after inclusion between participants randomly assigned to initiate ART immediately (hereafter, "early ART") or according to ongoing World Health Organization criteria. Group-specific HIV transmission rates were estimated on the basis of sexual behaviors and viral load-specific per-act HIV transmission probabilities. The ratio of transmission rates was computed to estimate the protective effect of early ART.

Results: Among 957 participants (baseline median CD4(+) T-cell count, 478 cells/mm(3)), 46.0% reported sexual activity in the past month; of these 46.0%, sexual activity for 41.5% involved noncohabiting partners. The proportion of subjects who engaged in risky sex was 10.0% in the early ART group, compared with 12.8% in the standard ART group (P = .17). After accounting for sexual behaviors and viral load, we estimated that the protective effect of early ART was 90% (95% confidence interval, 81%-95%).

Conclusion: Twelve months after inclusion, patients in the early and standard ART groups reported similar sexual behaviors. Early ART decreased the estimated risk of HIV transmission by 90%, suggesting a major prevention benefit among seronegative sex partners in stable or casual relationships with seropositive individuals.

Keywords: HIV prevention; HIV-1 sexual transmission; antiretroviral treatment; epidemiology; sexual behaviors; sub-Saharan Africa; treatment as prevention.

Figure 1.

Distribution of plasma human immunodeficiency virus type 1 (HIV-1) RNA, by antiretroviral (ART) strategy at baseline (A) and 12 months after inclusion (B). A, In the standard ART group, 4.3% had an undetectable viral load at baseline, and the mean viral load among individuals with a detectable viral load was 4.60 log₁₀ copies/mL (95% confidence interval [CI], 4.52–4.68). In the early ART group, 4.1% had an undetectable viral load at baseline, and the mean viral load among individuals with a detectable viral load was 4.63 log₁₀ copies/mL (95% CI, 4.55–4.71). B, In the standard ART group, 12.5% had an undetectable viral load 12 months after inclusion, and the mean viral load among individuals with a detectable viral load was 4.68 log₁₀ copies/mL (95% CI, 4.60–4.76). In the early ART group, 82.9% had an undetectable viral load 12 months after inclusion, and the mean viral load among individuals with a detectable viral load was 3.88 log₁₀ copies/mL (95% CI, 3.66–4.11). Patients in the early arm initiated ART immediately on inclusion in the trial, whereas patients in the standard arm delayed ART initiation until ongoing WHO starting criteria were met. A log₁₀ HIV-1 RNA load of <2.48 log₁₀ copies/mL corresponds to an HIV-1 RNA detectability threshold of <300 copies/mL.

Figure 2.

Estimated human immunodeficiency virus type 1 (HIV)–transmission rates at the last episode of sexual intercourse in the past month, by antiretroviral therapy (ART) strategy, per 10 000 sexually active participants (A; preventive effect, 89% [95% confidence interval {CI}, 79–95]) and per 10 000 participants (B; preventive effect, 90% [95% CI, 81–95]). Data are from 957 patients who participated in a sociobehavioral study nested in the Temprano trial and were recorded at the 12-month visit. Patients in the early arm initiated ART immediately on inclusion in the trial, whereas patients in the standard arm delayed ART initiation until ongoing WHO starting criteria were met. Per-act viral load–specific transmission probabilities are derived from Hughes et al [19]. Calculations accounted for sexual activity, condom use, circumcision, and partner's HIV infection status.