Assessing differences in groups randomized by recruitment chain in a respondent-driven sample of Seattle-area injection drug users
Published Date:Sep 10 2014
Source:Ann Epidemiol. 2014; 24(11):861-867.e14.
Pubmed Central ID:PMC4252737
Funding:R03 DA031072/DA/NIDA NIH HHS/United States
U1B PS003250/PS/NCHHSTP CDC HHS/United States
5U1BPS003250/PHS HHS/United States
Respondent-driven sampling (RDS) is a form of peer-based study recruitment and analysis that incorporates features designed to limit and adjust for biases in traditional snowball sampling. It is being widely used in studies of hidden populations. We report an empirical evaluation of RDS’s consistency and variability, comparing groups recruited contemporaneously, by identical methods and using identical survey instruments.
We randomized recruitment chains from the RDS-based 2012 National HIV Behavioral Surveillance survey of Seattle-area injection drug users into two groups and compared them in terms of sociodemographic characteristics, drug-associated risk behaviors, sexual risk behaviors, HIV status and HIV testing frequency.
The two groups differed in 5 of the 18 variables examined (p ≤ .001): race (for example, 60% white vs. 47%), gender (52% male vs. 67%), area of residence (32% downtown Seattle vs. 44%), an HIV test in the previous 12 months (51% vs. 38%). The difference in serologic HIV status was particularly pronounced (4% positive vs. 18%). In 4 further randomizations, differences in one to five variables attained this level of significance, though the specific variables involved differed.
We found some material differences between the randomized groups. While the variability of the present study was less than has been reported in serial RDS surveys, these findings indicate caution in the interpretation of RDS results.
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