title: Detoxification center-based sampling missed a subgroup of higher risk drug users, a case from Guangdong, China.
abstract: BACKGROUND
  Injection drug use remains among the most important HIV transmission risk in China. Representativeness of drug users sampled from detoxification centers is questionable. A respondent driven sampling survey was conducted to compare the results with those from the detoxification center in the same city.
  
  
  METHODS
  In 2008, two independent surveys were conducted in Dongguan, China, one for community-based drug users using respondent driven sampling and the other for drug users in a compulsory detoxification center as routine sentinel surveillance. Demographic and behavioral information were collected using the same structured questionnaire. Intravenous blood samples were collected to measure antibodies to HIV-1, and syphilis.
  
  
  RESULTS
  Compared to those 400 drug users recruited from the detoxification center, the 303 community-based drug users had higher HIV prevalence (14.7% versus 4.0%, P = 0.04), lower syphilis prevalence (4.7% versus 10.8%, P = 0.07), higher proportion of injection drug use (83.9% versus 60.2%, P = 0.01) and syringe sharing (47.8% versus 36.3%, P = 0.10), more likely to be separated (12.4% versus 3.8%, P = 0.01) and being migrants from Guangxi province (31.4% versus 18.0%, P = 0.09), more engaging in commercial sex (64.4% versus 52.5%, P = 0.04). HIV prevalence and rate of syringe sharing were consistently higher among drug users from Guangxi.
  
  
  CONCLUSIONS
  Detoxification center-based sampling missed a subgroup with higher HIV prevalence and higher rate of injection drug use. While detoxification center-based sampled can be used to monitor the trend of HIV prevalence and risk behaviors over time, periodic community-based sampling is still necessary to avoid possible systematic error in detoxification center-based samples.
authors.affiliation: Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Lin
authors.forename: Man
authors.initials: M
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Qiaoli
authors.initials: Q
authors.lastname: Zhang
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.forename: Jinkou
authors.initials: J
authors.lastname: Zhao
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D055030:Drug Users; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000635:transmission*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D018571:Sentinel Surveillance; D012725:Sexual Behavior; D013587:Syphilis / Q000453:epidemiology / Q000635:transmission; D055815:Young Adult