Serosorting can have potential benefits including reduction in HIV incidence and better ART adherence and retention. Although serosorting behavior has been reported among high risks groups such as men who have sex with men, its role is largely unknown in heterosexual couples in a high HIV endemic setting in sub-Saharan Africa.
Data from a population-based open cohort between January 2003 and December 2016 in KwaZulu-Natal, South Africa was used. Individuals with known HIV status, not currently in stable conjugal relationship (CR), were included for the analysis. Competing-risks survival regression was used to estimate the incidence of conjugal relationship formation with known HIV seropositive partners by participants’ HIV status, where formation with known seronegative or unknown serostatus partners was fitted as the competing risks. HIV status was used as a time-varying exposure. Hazard ratios (HR) and 95% confidence intervals (CI) are reported.
A total of 24,232 HIV-negative and 10,384 HIV-positive individuals including 3,345 who seroconverted were followed over 166,686 person-years (PY) follow-up time. We observed 68 (0.4 per 1000 PY) CR formation with known HIV seropositive, 193 (1.2/1000 PY) with known seronegative and 385 (2.3/1000 PY) with unknown serostatus partners. The average median age at the time of CR formation was 27 (IQR:21-36). HIV-positive individuals had 2.17 (95% CI: 1.29-3.64) times higher hazard of CR formation with a HIV-positive partner, compared to HIV-negative individuals. The adjusted HR was 2.26 (95% CI: 1.29-3.96) after adjusting for age, sex, education, household asset, and the number of partners in the past 12 months. When stratified by participants’ age at <30 vs. 30+ years, the association became only significant in those aged 30+ years (HR=4.11; 95% CI: 1.93-8.73).
Positive serosorting was observed among HIV-positive individuals in older heterosexual couples in rural KwaZulu-Natal, South Africa. Such behavior might be due to increased knowledge for HIV and access to antiretroviral therapy (ART) care and may lead to better long-term health outcomes.