Adopting LMS Method To Estimate The Size Of MSM Populations In Urban Area Of Changsha

Background In recent years, the infection rate of HIV was constantly increasing in Men who have Sex with Men population (MSM). The proportion of the new HIV infections caused by MSM behavior was rapidly growing and still accelerating. The risk for MSM in China to infect HIV is higher than general population, so MSM become at risk population of HIV/AIDS. China has established a relatively complete HIV/AIDS monitoring system, which enables us to know the number of all the new HIV infectors. We can understand the constituent situation of all the new HIV infections approaches through some epidemiology researches. Because MSM are sensitive and hard to reach, some current methods have limitations in estimation the size of MSM, especially on the Internet virtual venues. So it is still tough to obtain the precise size of MSM populations and understand the general social features, the safe sex behavior characteristics, also especially those on the Internet virtual venues.Objective The study tried to adopt LMS method originated by Laska, Meisner and Siegel to estimate the size of MSM. LMS method provided some new ideas to estimate the hard-to-reach population, including MSM. The study understood the MSM social features in different venues. All outcomes were important to forecast and prevent the HIV/AIDS epidemic and implement the prevention strategies aimed to MSM.Methods We implement the survey in MSM venues adopting cross-sectional study. Using the questionnaire survey to understand the MSM social features and the safe sex behavior characteristics in actual and virtual venues, and using LMS method to estimate the MSM size of different venues in Changsha, we tried to modify original LMS simply and feasibly, fitting for MSM social features and obtaining more reasonable size.Results According to LMS method and some modifications, the result showed that the number of MSM was65657, constituting a proportion of5.43%(95%CI:4.79%～6.07%) in the sexually active male population in Changsha. The MSM socialize in multiple venues consisted of actual and virtual. Four actual venues were identified, including three bathrooms and one music bar, and there were about100to150QQ groups and two websites. The number of respondents in actual venues was566; most of them were24～43years old and had secondary education. Whereas the number of respondents in virtual venues was3126, the majority of this population was less than29years old and had higher education. The differences of occupational constituent were statistical significance between actual venues and virtual venues. The ratio of students in virtual venues was39.09%, while the ratio of students in actual venues was only3.18%. The awareness of AIDS of the two groups from different venues showed no statistically significant difference, neither the safe sex behavior.Conclusion The MSM social features can meet the LMS condition of application in the main. After the reasonable reforms and result modifications of LMS method, the MSM size was more authentic. When adopting LMS to estimate MSM size, required information is non-sensitive, privacy-free and practicable, so investigators obtained accurate information. LMS method could be applied in MSM size estimation on Internet virtual venues, and it provided some new ideas for estimating the size of MSM populations. In Changsha, the MSM population was in a large size and was characterized differently in actual and virtual venues. As most MSM preferred virtual venue, the intervention in this area especially Internet should be paid more attention and the AIDS-specific strategy should be implemented.