Case-control study of risk factors for incident HIV infection in rural Uganda

Objective: To identify risk factors associated with HIV incidence in a rura l Ugandan population. Design: Case-control study. Methods: Men and women who seroconverted between 1990 and 1997 (cases) and seronegative subjects (controls) were drawn from a general population cohor t of approximately 5000 adults in rural, southwestern Uganda. information o n risk factors was ascertained through a detailed interview and physical ex amination by clinicians who were blind to the study subjects' HIV status. A ll patients were interviewed within 2 years of their estimated date of sero conversion. Results: Data were available on 130 men (37 cases, 93 controls) and 133 wom en (46 cases, 87 controls). There was a significantly higher risk of infect ion in men (odds ratio [OR], 6.51; 95% confidence interval [CT], 1.06-39.84 ) and women (OR, 4.75; 95% CT, 1.26-17.9) who were unmarried and in a stead y relationship, and in men who were divorced, separated, or widowed (OR, 4. 33; 95% CI, 1.32-14.25) compared with those who were married. There was a s ignificantly higher risk of HIV infection in men (OR, 3.78; 95% CI, 1.20-11 .93) and women (OR, 20.78; 95% CI, 2.94-141.2) who reported greater than or equal to 5 lifetime sexual partners compared with those who reported at mo st 1 partner. For men, there was an increased risk of infection associated with receiving increasing numbers of injections in the 6 months prior to in terview (p < .001 for trend). Women reporting sex against their will in the year prior to interview were at higher risk of infection (OR, 7.84; 95% CI , 1.29-47.86,; p = .020). Conclusions: The strongest risk factor for HIV incidence in this rural Ugan dan population is lifetime sexual partners. The increased risks found for w omen reporting coercive sex and men reporting injections require further in vestigation.