Background: We aimed to assess audio-computer-assisted self-interviewing (audio-CASI) as a method of reducing under-reporting of HIV risk behaviour among injecting drug users.
Methods: Injecting drug users were interviewed at syringe-exchange programmes in four US cities. Potential respondents were randomly selected from participants in the syringe exchanges, with weekly alternate assignment to either traditional face-to-face interviews or audio-CASI. The questionnaire included items on sociodemographic characteristics, drug use, and HIV risk behaviours for 30 days preceding the interview. We calculated odds ratios for the difference in reporting of HIV risk behaviours between interview methods.
Findings: 757 respondents were interviewed face-to-face, and 724 were interviewed by audio-CASI. More respondents reported HIV risk behaviours and other sensitive behaviours in audio-CASI than in face-to-face interviews (odds ratios for reporting of rented or bought used injection equipment in audio-CASI vs face-to-face interview 2.1 [95% CI 1.4-3.3] p=0.001; for injection with borrowed used injection equipment 1.5 [1.1-2.2] p=0.02; for renting or selling used equipment 2.3 [1.3-4.0] p=0.003).
Interpretation: Although validation of these self-reported behaviours was not possible, we propose that audio-CASI enables substantially more complete reporting of HIV risk behaviour. More complete reporting might increase understanding of the dynamics of HIV transmission and make the assessment of HIV-prevention efforts easier.