同伴推动抽样法在社区吸毒人群HIV/STI调查中应用的方法学探讨

Application of respondent-driven sampling in recruiting community-based drug users for HIV/STI epidemiological survey:a methodological assessment

目的探索同伴推动抽样法（respondent-driven sampling,RDS）在社区吸毒人群HIV/STI流行病学调查中应用的可行性。方法2008年选择佛山市南海区和东莞市,借助当地的美沙酮维持治疗（methadone maitenance treatment,MMT）门诊选择初级种子,采用限额招募和双向激励机制招募社区吸毒人群进行HIV/STI相关行为学调查和生物学检测。其中南海调查地点为美沙酮门诊,招募限额为3,激励机制早期为超市购物券,3个月后增加部分现金;东莞调查地点为健康体检门诊,招募限额为5,激励机制为现金。对所得数据利用RDSAT进行统计学校正。结果佛山市南海区17名种子经过26周共招募127名社区吸毒人员,招募人数达到预期样本量的63.5%,每周招募人数为0~16人,中位数为4,招募链最长为8轮,其中3条招募链超过3轮,所招募人数占总招募数的70.1%;东莞市13名种子经过15周共招募290名社区吸毒人员,达到预期样本量的145%,每周招募人数为5~41人,中位数为17,最长招募链为11轮,2条招募链超过3轮,所招募人数占总招募数的88.6%。南海和东莞的招募样本分别在第6轮、第8轮达到平衡;经RDSAT校正后,估计南海区及东莞市吸毒人群参加MMT的比例分别为15.7%、8.4%。结论RDS用于社区吸毒人群的HIV/STI流行病学调查是可行的,使调查对象感到安全的地点和适当水平的激励机制是促使目标人群参与的关键因素。

Objective To explore the feasibility of respondent - driven sampling （RDS） in recrui- ting community - based drug users for HIV/STI epidemiological survey. Methods In 2008, RDS was applied to recruit community - based drug users for HIV/STI behavioral and biological surveillance in Nanhai and Donggnan, two areas of the Pearl River Delta region of Guangdong Province. The initial seeds were chosen through the methadone maintenance treatment （MMT） clinics, and the quotalimiting recruitment and the dual incentive mechanism were applied. In Nanhai, the interview site was the MMT clinic. Three coupons were given to each participant to recruit his/her peers, and supermarket vouchers were offered as incentive at first and some cash was added three months later. While in Dongguan, the physical examination clinic was selected as interview site, and 5 coupons with cash incentives were offered. RDSAT was adopted for adjusting the estimates. Results In Nanhai, 17 seeds recruited 127 community - based drug users within 26 weeks, which accounted for 63.5% of the pre - defined sample size. The drug users successfully recruited every week varied from 0 to 16, with a median of 4. The longest seed -linked wave was 8, and 3 seed - lined waves were longer than 3 which accounted for 70. 1% of the recruit sample. While in Dongguan 13 initial seeds recruited 290 community drug users successfully within 15 weeks, which reached 145% of the pre - defined sample size. The drug users successfully recruited every week varied from 5 to 41, with a median of 17. The longest wave was 11, with 2 seed - linked waves longer than 3 which accounted for 88.6% of the recruitment sample. The equilibrium was reached in the sixth and eighth waves in Nanhai and Dongguan, respectively. The adjusted percentages of the drug users who attended MMT in Nanhai and Dongguan were 15.7% and 8.4%, respectively. Conclusion RDS is an effective way to recruit community- based drug users for HIV/STI survey. Safe interview site and appropriate incentive were the two most important factors associated with the recruitment efficiency.