Quantifying geographical diversity in sexually transmitted infections using population attributable risk: results from HIV prevention trials in South Africa.

In this study, we investigated spatial diversities of sexually transmitted infections (STIs) and quantified their impacts on the STIs using population attributable risk (PAR%). The study population was 7,557 women who participated in several HIV prevention trials from KwaZulu-Natal, South Africa. Our results provide compelling evidence for substantial geographical diversities on STI incidence rates in the region. Their population-level impacts on the STIs exceeded the combined impacts of the individual risk factors considered in this study (PAR%: 41% (<25 years), 52% (25-34 years) and 34% (35+ years). When all these factors are considered together, PAR% was the highest among younger women (PAR%: 67%, 82% and 50% for <25, 25-34 and 35+ years old respectively). Results from our study will bring greater insight into the previous research by increasing our understanding of the impacts of the sub-geographical level variations of STI prevalence and incidence rates in the region.