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.