title: Comparing respondent-driven sampling and targeted sampling methods of recruiting injection drug users in San Francisco.
abstract: The objective of this article is to compare demographic characteristics, risk behaviors, and service utilization among injection drug users (IDUs) recruited from two separate studies in San Francisco in 2005, one which used targeted sampling (TS) and the other which used respondent-driven sampling (RDS). IDUs were recruited using TS (n = 651) and RDS (n = 534) and participated in quantitative interviews that included demographic characteristics, risk behaviors, and service utilization. Prevalence estimates and 95% confidence intervals (CIs) were calculated to assess whether there were differences in these variables by sampling method. There was overlap in 95% CIs for all demographic variables except African American race (TS: 45%, 53%; RDS: 29%, 44%). Maps showed that the proportion of IDUs distributed across zip codes were similar for the TS and RDS sample, with the exception of a single zip code that was more represented in the TS sample. This zip code includes an isolated, predominantly African American neighborhood where only the TS study had a field site. Risk behavior estimates were similar for both TS and RDS samples, although self-reported hepatitis C infection was lower in the RDS sample. In terms of service utilization, more IDUs in the RDS sample reported no recent use of drug treatment and syringe exchange program services. Our study suggests that perhaps a hybrid sampling plan is best suited for recruiting IDUs in San Francisco, whereby the more intensive ethnographic and secondary analysis components of TS would aid in the planning of seed placement and field locations for RDS.
authors.affiliation: Urban Health Program, RTI International, 114 Sansome Street, Suite 500, San Francisco, CA 94104, USA. akral@rti.org
authors.forename: Alex H
authors.initials: AH
authors.lastname: Kral
authors.forename: Mohsen
authors.initials: M
authors.lastname: Malekinejad
authors.forename: Jason
authors.initials: J
authors.lastname: Vaudrey
authors.forename: Alexis N
authors.initials: AN
authors.lastname: Martinez
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lorvick
authors.forename: Willi
authors.initials: W
authors.lastname: McFarland
authors.forename: H Fisher
authors.initials: HF
authors.lastname: Raymond
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000523:psychology / Q000706:statistics & numerical data; D016001:Confidence Intervals; D015340:Epidemiologic Research Design; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D006306:Health Surveys / Q000379:methods*; D006526:Hepatitis C / Q000150:complications / Q000453:epidemiology; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D018671:Needle-Exchange Programs / Q000706:statistics & numerical data; D018579:Patient Selection; D012107:Research Design; D012309:Risk-Taking; D012494:Sampling Studies; D012495:San Francisco / Q000453:epidemiology; D016320:Substance Abuse Treatment Centers / Q000706:statistics & numerical data; D015819:Substance Abuse, Intravenous / Q000453:epidemiology* / Q000523:psychology* / Q000534:rehabilitation / Q000821:virology; D014505:Urban Population / Q000706:statistics & numerical data; D055815:Young Adult