HIV-1 seroconversion in United States Army active duty personnel, 1985-1999.

Objective To monitor HIV-1 infection trends among United States Army personnel, a predominantly young population group, tested between 1985 and 1999 for HIV-1 infection. Design Demographic correlates of HIV-1 infection were assessed in the cohort via epidemiologic analysis. Methods Annual seroconversion incidence rates were calculated per 1000 person-years (PY) of follow-up. Poisson regression was used to assess demographic correlates of HIV-1 seroconversion risk. Results There were 1275 seroconverters among 2 004 903 active duty Army personnel accounting for 7 700 231 PY of follow-up. The HIV-1 incidence rate (IR) was 0.17/1000 PY [95% confidence interval (CI), 0.16–0.17]. The highest IR was observed in the first year of testing (IR, 0.43/1000 PY; 95% CI, 0.33–0.52). The IR for male and female soldiers was 0.18/1000 PY and 0.08/1000 PY, respectively. HIV-1 incidence declined with age. Significant risk of HIV-1 seroconversion was associated with age [> 30 years old relative risk (RR), 1.51], race (Black RR, 4.61; Hispanic RR, 2.76), gender (male RR, 3.12), marital status (unmarried RR, 2.01) and rank (enlisted RR, 2.50). Conclusions HIV-1 seroconversions in the US Army have been low and stable since the early 1990s. Continued HIV-1 incidence surveillance in the US Army provides information on the status of the epidemic in the Army, as well as important corroborative data on HIV-1 infections throughout the US.