Audio-computer interviewing to measure risk behaviour for HIV among injecting drug users: a quasi-randomised trial

Background We aimed to assess audio-computer-assisted self-interviewing (au dio-CASI) as a method of reducing underreporting of HIV risk behaviour amon g injecting drug users. Methods Injecting drug users were interviewed at syringe exchange programme s in four US cities. Potential respondents were randomly selected from part icipants in the syringe exchanges, with weekly alternate assignment to eith er traditional face-to-face interviews or audio-CASI. The questionnaire inc luded items on sociodemographic characteristics, drug use, and HIV risk beh aviours for 30 days preceding the interview. We calculated odds ratios for the difference in reporting of HIV risk behaviours between interview method s. Findings 757 respondents were interviewed face-to-face, and 724 were interv iewed by audio-CASI. More respondents reported HIV risk behaviours and othe r 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 no t possible, we propose that audio-CASI enables substantially more complete reporting of HIV risk behaviour. More complete reporting might increase und erstanding of the dynamics of HIV transmission and make the assessment of H IV-prevention efforts easier.