Jillian Pintye1,2, Alison L. Drake1, John Kinuthia4, Jennifer A. Unger1,3, Daniel Matemo4, Renee Heffron1, Ruanne Barnabas1,5,8, Pamela Kohler1,2, R. Scott McClelland1,5,6,7, and Grace John-Stewart1,5,6,8
Background: An HIV risk assessment tool for pregnant women could identify women who would most benefit from PrEP while minimizing unnecessary PrEP exposure
Methods: Data from a prospective study of incident HIV among pregnant/postpartum women in Kenya was randomly divided into derivation (n=654) and validation (n=650) cohorts. A risk score was derived using multivariate Cox proportional hazards models and standard clinical prediction rules. Ability of the tool to predict maternal HIV acquisition was assessed using the area under the curve (AUC) and Brier score.
Results: The final risk score included the following predictors: having a male partner with unknown HIV status, number of lifetime sexual partners, syphilis, bacterial vaginosis (BV), and vaginal candidiasis. In the derivation cohort, AUC was 0.84 (95% CI 0.72-0.95) and each point increment in score was associated with a 52% (hazards ratio [HR] 1.52, 95% CI, 1.32-1.76, p<0.001) increase in HIV risk; the Brier score was 0.11. In the validation cohort, the score had similar AUC, Brier score and estimated HRs. A simplified score that excluded BV and candidiasis yielded an AUC of 0.76 (95% CI 0.67-0.85); HIV incidence was higher among women with risk scores >6 than with scores 6 (7.3 vs. 1.1 per 100 person-years, respectively; p<0.001). Women with simplified scores >6 accounted for 16% of the population but 56% of HIV acquisitions.
Conclusion: A combination of indicators routinely assessed in antenatal clinics was predictive of HIV risk and could be used to prioritize pregnantwomen for PrEP.