Assessing and evaluating the combined impact of behavioural and biological risk factors for HIV seroconversion in a cohort of South African women.

In this prospective study, we aimed to investigate and evaluate the impact of combinations of behavioural and biological risk factors on HIV acquisition in a cohort of women. Demographic, sexual and biologic risk factors including HIV seroconversion results from 1485 HIV negative women who were enrolled in a HIV prevention trial were used. First, Cox regression models were used to create a prediction model and weighted scoring system. Second, internal validation data-set was used to evaluate the performance characteristics of the model prospectively. In the prediction model, an increasing number of lifetime sexual partners, women who were classified as in a "high risk behavior" group, and those who were not cohabitating with their partners were consistently associated with increased risk of HIV acquisition. Among the baseline biological factors, genital epithelial disruption, genital signs and symptoms, genital discharge and detecting edema, erythma or warts in vulva were all associated with HIV seroconversion. High scores were associated with increased risk of HIV seroconversion. A cut-point score of 15 (out of 44) or higher distinguished an "increased risk" group with a sensitivity of 88%. This study presents reasonable robust analyses for investigating and evaluating epidemiological measures on HIV infection. Results from this study may be included as part of a health promotion to prompt those who are at increased risk of HIV infection which may potentially lead to increased uptake and frequency of testing.