Sampling methods used in developed countries for behavioural surveillance among men who have sex with men.

The aim of this review was to develop an overview of the sampling methods used in developed countries for behavioural surveillance among men who have sex with men. We abstracted information from peer-reviewed and non-peer-reviewed publications and, when needed, contacted first authors and surveillance authorities. Out of the 40 developed countries, 26 surveillance systems were identified in 23 countries. These surveillance systems made use of one or a combination of: venue-based sampling (n = 16); web-based sampling (n = 11); gay press/mail-out (n = 8); or respondent-driven sampling (n = 4). Differences in the sampling methods used were found by year of implementation and by region. More information is needed to better assess the strengths and limitations of the range of sampling methods. There was substantial variation in the way sampling methods were applied, most especially in venue-based sampling. To improve the ability to compare indicators across countries, key elements of the sampling methods should be standardized.