In serodiscordant heterosexual couples, undetectable viral load (VL) is associated with a substantially reduced HIV transmission risk. No studies in gay male serodiscordant couples (SDCs) have been reported. ‘Opposites Attract’ is an ongoing cohort study of gay SDCs recruited via clinics and community-based advertising. HIV-Positive Partners (HPPs) have VL tested at baseline; HIV- Negative Partners (HNPs) have HIV antibody tests and report sexual behaviour and partner’s perceived VL. Associations between unprotected anal intercourse (UAI) and VL were examined with logistic regression and Wilcoxon rank-sum test.
As of April 2013, 64 couples were enrolled. At baseline, 84.4% (n=54) of HPPs were taking ART and 76.6% (n=49) had undetectable VL. Overall, 68.8% (n=44) of HNPs reported any UAI with their partners: 59.4% of HNPs reported any insertive UAI, 37.5% reported receptive UAI without ejaculation, and 21.9% reported receptive UAI with ejaculation. 78.1% of HNPs believed their HPP’s last VL test result to be undetectable. The HNP’s perception of his partner’s VL was mostly in accord with the baseline test results. In the couples with perceived undetectable VL, 78.0% reported UAI in the last three months. In comparison, only 35.7% of couples in which the HPP’s VL was perceived to be detectable (n=8) or where the VL result was not known (n=3) reported UAI (OR=0.16, 95%CI=0.04-0.56, p=0.005). Overall, the median number of UAI acts in the last three months was 4 (range=0-183, mean=18.5, SD=34.0). The median number of UAI acts was 6.5 in couples where the HNP believed his partner’s VL was undetectable. This compared to 0 in couples where the perceived VL was detectable or was not known (p=0.007).
Among Australian gay male SDCs, perceived undetectable VL is strongly related to increased practice of UAI. Studies of HIV transmission risk in this population are an urgent research priority.
