Evaluation of the Center for Disease Control and Prevention's HIV behavioral surveillance of men who have sex with men: sampling issues.

Background: The Centers for Disease Control and Prevention is embarking on a program of biannual venue-based time-space sampling surveys to monitor prevalence and incidence of HIV among men who have sex with men (MSM).

Goal: We examine the efficacy of the suggested methodology in terms of population coverage, sample period, range of venues, and representativeness.

Study: The 2002 Urban Men's Health Study (N = 879) is a telephone interview of a household probability sample of adult MSM living in San Francisco.

Results: A 6-month bar/club sample would capture 79% of the adult MSM population and yield an accurate estimate of HIV prevalence. Using a longer sample period or sampling other less-frequented venues yields marginal improvement. Risk behavior, when broadly defined, is overestimated.

Conclusions: The National HIV Behavioral Surveillance of MSM protocol may be satisfactory for sampling urban MSM within defined limits, but could be conducted at significantly less cost by reducing the types of venues and fielding time. However, bias in the venue sample with respect to risk behavior and other key correlates argues for validity checks based on household probability samples conducted at infrequent intervals.