Multiplier method estimates of the population of men who have sex with men: the effect of privacy protection.

OBJECTIVES: The stigmatization of men who have sex with men (MSM) has led to an underestimation of their population size. To address this, the United Nations Programme on HIV/Acquired Immunodeficiency Syndrome and World Health Organization developed a multiplier method. However, nearly all multiplier method estimates of MSM population size in China are far below national estimates. This study explores how privacy protection to address and avoid MSM stigmatization can affect reliable estimates.

METHODS: Data from an MSM website, a bar, and a peer-based HIV testing were used to produce three multiplier method estimates of the MSM population size in Taiyuan, China, in 2014. The effect of privacy protection on stigmatization was explored by comparing the peer-based HIV testing with other estimates. We used a national estimate as a reference to verify potential underestimation.

RESULTS: The website and bar estimates were 5- to 10-times and 8- to 16-times lower than the Chinese national estimate range, respectively. Conversely, the peer-based HIV testing estimate was within the national estimate range.

CONCLUSIONS: Though the multiplier method was developed to estimate the size of stigmatized populations, it might be affected by privacy protection addressing stigmatization; this should be considered when gathering data.