Prevalence of sexually transmitted infections and bacterial vaginosis among women in sub-Saharan Africa: an individual participant data meta-analysis of 18 HIV prevention studies

Abstract

Background: Estimates of sexually transmitted infection (STI) prevalence are essential for efforts to prevent and control STIs. Few large STI prevalence studies exist, especially for low- and middle-income countries (LMICs). Our primary objective was to estimate prevalence of chlamydia, gonorrhea, trichomoniasis, syphilis, HSV-2, and bacterial vaginosis (BV) among women in sub-Saharan Africa by age, region, and population-type.Methods and Findings: We analyzed individual-level data from 18 HIV prevention studies (cohort studies, randomized controlled trials; conducted during 1993–2011), representing >37,000 women, which tested participants for ≥1 selected STI/BV at baseline. We used a two-stage meta-analysis to combine data. After calculating the proportion with each STI/BV and standard error by study, we used a random-effects model to obtain a summary mean prevalence of each STI/BV and 95% confidence interval (CI) across age, region, and population-types. Despite substantial study heterogeneity for some STIs/populations, several patterns emerged. Across all regions/population groups, prevalence was higher among 15–24 year-old than 25–49 year-old women for all STIs except HSV-2. In general, higher-risk populations had greater prevalence of gonorrhea and syphilis than clinic/community-based populations. For chlamydia, prevalence among 15–24 year olds was 10.3% (95% CI: 7.4, 14.1; I2=75.7%) among women specifically recruited from higher-risk settings for HIV in Eastern Africa and was 15.1% (95% CI: 12.7, 17.8; I2=82.3%) in South African clinic/community-based populations. Among clinic/community-based populations, prevalence was generally greater in South Africa than in Southern/Eastern Africa for most STIs; for gonorrhea, prevalence among 15–24 year olds was 4.6% (95% CI: 4.4, 6.4; I2=82.8%) in South Africa and was 1.7% (95% CI: 1.2, 2.6; I2=55.2%) in Southern/Eastern Africa. Across all region/population groups, HSV-2 and BV prevalence was high among 25–49 year-olds (ranging from 70–83% and 33–44%, respectively). The main study limitation is that the data are not from random samples of the target populations. Conclusions: Combining data from 18 HIV prevention studies, our findings highlight important features of STI/BV epidemiology among sub-Saharan African women. This methodology can be used where routine STI surveillance is limited and offers a new approach to obtaining critical information on STI and BV prevalence in LMICs.

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ORCID for Nuala Mcgrath: orcid.org/0000-0002-1039-0159

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