Application of capture and recapture method to estimate the population size of men who have sex with men among college students in Hangzhou

Objective To determine current same-sex social software usage among college students in Hangzhou and to estimate the population size,as to provide evidence for HIV/AIDS prevention among male college students who have sex with men (MSM).Methods On 15th April 2017,the numbers of MSM among college students from universities located in advanced education zone were collected according to log records in same-sex social software,and the process was repeated after 7 days.The population size of MSM among college students in Hangzhou was recorded by the capture and recapture method.Results The population size of MSM was about 2 636 (95%CI:2 522-2 750),with average age (20.75±2.00) years old.Average weight and height was (63.58± 11.82) kg and (175.86±8.89) cm.Among the classification of sex roles,21.11% (400) played both the top and bottom role,21.39%(405) reported only the bottom role and 14.78%(280) played the top role.Conclusion Same-sex social software provides a new approach to estimate the population size of MSM by using the application of capture and recapture method.In the meanwhile,it provides a new carrier to start propaganda and education work on male homosexuality among young students in high school.It is worth considering to carry out more studies on roles of new media technology in HIV/AIDS program in the future.