捕获—再捕获法对南京市男男性行为人群的估算调查

Estimation of population size of men who have sex with men in Nanjing city by capture-recapture method and investigation of their relative behaviors

目的 估算南京市男男性行为人群基数,并对其相关行为进行调查,为性病防治工作提供基线资料。方法 利用捕获—再捕获法（C-R）,对南京市MSM人群基数进行估计,在第二次捕获过程中同时开展问卷调查,了解MSM的相关行为和HIV、梅毒感染状况。结果 第一次捕获共473人参加并被标记,第二次捕获共招募合格对象439人,其中11人曾被标记。捕获—再捕获法估计南京市MSM人群基数为17 379人（95%CI：81 80-26 578）,占同年龄段男性总人口数的0.5%（0.2%-0.7%）。接受问卷调查的439例调查对象中,有412例知晓艾滋病预防知识,知晓率为93.9%;有82.5%最近6个月内与同性有过肛交性行为,63.5%存在多性伴;52.2%发生过无保护性肛交性行为,7.7%过去一年曾被诊断患过性病。血清学检测结果：HIV感染率11.8%,既往梅毒感染率15.5%,现症梅毒感染率6.4%。结论 捕获—再捕获法可以估计MSM人群规模,为性病艾滋病预防提供基础数据。南京地区MSM人群HIV感染率高,并存在多性伴、不安全性行为,需对该类人群的行为进行干预,以控制性病艾滋病的传播流行。

Objectives To estimate population size and investigate related behaviors of men who have sex with men （MSM） in Nanjing city; to provide fundamental data for HIV control and prevention. Methods Capture-recapture method was used to estimate population size of MSM in Nanjing city. Questionnaire based investigation was conducted at recapture phase to obtain information of MSM＇s relative behaviors; serological test was carried out to investigate prevalence of HIV and syphilis. Re- sults A total of 473 MSM were captured and marked at first capture phase; while 439 qualified MSM were recruited at recap- ture phase, among which 11 were marked in the first capture phase. The estimated population size of MSM in Nanjing was 17 379 （95%CI： 8 180-26 578） calculated by capture-recapture method formula, which accounted for 0.5%（0.2%-0.7%） of male population of corresponding ages. Among 439 participants who completed survey questionnaires, 412 had awareness of HIV knowledge, resulting awareness rate of 93.9%; 82.5% had homosexual anal intercourses in past 6 months; 63.5% had multiple sex partners; 52.2% had unprotected anal intercourses; 7.7% were diagnosed for STDs infection in past year. Sero- logical analysis showed HIV infection rate of 11.8%, previous syphilis infection rate of 15.5% and current infection rate of 6.8%. Conclusion Capture-recapture method could be used to estimate MSM population size, which provided basic data for lo- cal HIV prevention and control. MSM in Nanjing area had a relatively high HIV prevalence; multiple sex partners, unprotect- ed anal intercourses. High risk behavior interventions should be strengthened to control HIV/AIDS spreading in Nanjing city.