Journal of Urban Health

, Volume 87, Issue 5, pp 839-850

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Comparing Respondent-Driven Sampling and Targeted Sampling Methods of Recruiting Injection Drug Users in San Francisco

  • Alex H. KralAffiliated withUrban Health Program, RTI InternationalUniversity of California Email author 
  • , Mohsen MalekinejadAffiliated withInstitute for Global Health, University of California
  • , Jason VaudreyAffiliated withSan Francisco Department of Public Health
  • , Alexis N. MartinezAffiliated withDepartment of Sociology, San Francisco State University
  • , Jennifer LorvickAffiliated withUrban Health Program, RTI InternationalSchool of Public Health, University of California
  • , Willi McFarlandAffiliated withUniversity of CaliforniaSan Francisco Department of Public Health
  • , H. Fisher RaymondAffiliated withSan Francisco Department of Public Health


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.


IDU Methods Epidemiology RDS Targeted sampling Geography