Background and objectives: Heterosexual HIV-1–serodiscordant couples are increasingly recognized as an important source of new HIV-1 infections in sub-Saharan Africa. A simple risk assessment tool could be useful for identifying couples at highest risk for HIV-1 transmission.
Methods: Using data from 3 prospective studies of HIV-1–serodiscordant couples from 7 African countries and standard methods for development of clinical prediction rules, the authors derived and validated a risk scoring tool developed from multivariate modeling and composed of key predictors for HIV-1 risk that could be measured in standard research and clinical settings.
Results: The final risk score included age of the HIV-1–uninfected partner, married and/or cohabiting partnership, number of children, unprotected sex, uncircumcised male HIV-1–uninfected partner, and plasma HIV-1 RNA in the HIV-1–infected partner. The maximum risk score was 12, scores ≥5 were associated with an annual HIV-1 incidence of >3%, and couples with a score ≥6 accounted for only 28% of the population but 67% of HIV-1 transmissions. The area under the curve for predictive ability of the score was 0.74 (95% confidence interval: 0.70 to 0.78). Internal and external validation showed similar predictive ability of the risk score, even when plasma viral load was excluded from the risk score.
Conclusions: A discrete combination of clinical and behavioral characteristics defines highest risk HIV-1–serodiscordant couples. Discriminating highest risk couples for HIV-1 prevention programs and clinical trials using a validated risk score could improve research efficiency and maximize the impact of prevention strategies for reducing HIV-1 transmission.
Departments of *Epidemiology
‖Pediatrics, University of Washington, Seattle, WA
¶Department of Epidemiology and Biostatistics, Makerere University, Kampala, Uganda
#Research Care Training Program, Center for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
**Department of Obstetrics and Gynecology, University of Nairobi and Kenyatta National Hospital, Nairobi, Kenya
††Kilimanjaro Christian Medical Centre, Moshi, Tanzania.
Correspondence to: Erin M. Kahle, Department of Epidemiology, University of Washington, 908 Jefferson Street, 12th Floor, Box 359927, Seattle, WA 98104 (e-mail: firstname.lastname@example.org).
Supported by the United States National Institutes of Health (grant R01-MH095507) and the Bill and Melinda Gates Foundation (grants 26469, 41185 and 47674).
Presented in part at the 19th Conference on Retroviruses and Opportunistic Infections, Seattle, March 5–8, 2012, Seattle, WA.
The authors have no conflicts of interest to disclose.
Received June 29, 2012
Accepted October 28, 2012