Background. Sexually transmitted infections (STIs) among people living with HIV/AIDS can facilitate the spread of HIV.
Objectives. To estimate STI incidence and identify predictors of STI acquisition among HIV-positive patients during their first 24 months of antiretroviral therapy (ART) in Johannesburg, South Africa.
Methods. We conducted a cohort study using prospectively collected routine data on patients who initiated ART between January 2004 and January 2015 at the Themba Lethu HIV clinic in Johannesburg. Kaplan-Meier analysis was used to estimate STI incidence rates (based on evidence of laboratory diagnosis and STI syndromic treatment prescription records). STI predictors were identified using Cox regression analysis.
Results. Among 26 762 adult patients on ART, there were 1 906 (7.1%) cases of STI (incidence 4.8/100 person-years; 95% confidence interval (CI) 4.7 – 5.1). Non-pregnant women were 60% more likely than men to be diagnosed with an STI (adjusted hazard ratio (aHR) 1.6; 95% CI 1.4 – 1.8). The risk of STI decreased with increasing baseline CD4 count (aHR 0.8, 0.5 and 0.4 for CD4 counts 101 – 200, 201 – 350 and >350 cells/μL, respectively, compared with CD4 count <100 cells/μL). Patients with advanced baseline World Health Organization (WHO) clinical stages had a higher risk (aHR 1.6 for WHO stage 4; 95% CI 1.3 – 1.9) compared with those with WHO stage 1. However, there was a 20% increase in the risk of STI among obese patients compared with underweight patients (aHR 1.3; 95% CI 1.0 – 1.7). Over 80% of obese patients diagnosed with an STI had a CD4 count <200 cells/μL.
Conclusions. STIs are common in HIV-infected patients who are receiving ART. While both ART and the syndromic management of STIs are high-impact interventions for controlling the spread of HIV, closer monitoring of STI occurrences is warranted, particularly among immunologically vulnerable patients.