Self-reports of alcohol use, drug use and sexual behavior: Expanding the timeline follow-back technique

Objective: The purpose of this study is to compare reports of alcohol use, drug use and sexual behavior from 30-day Summary measures with an expanded version of a Timeline Follow-back (Timeline) interview technique among gay/bisexual men entering outpatient substance abuse treatment at a gay-identified agency. Method: Respondents (N = 418) first completed self-administered questionnaires covering the 30-day period prior to their last use of alcohol or drugs. Summary measures included alcohol use, number of days of use for five categories of drugs and number of episodes of anal intercourse (with and without condoms) by partner type (primary or secondary). Participants then completed the Timeline interview procedure to recall their daily drinking, drug use and sexual behavior during the same 30-day period. Results: The findings indicate that the Timeline method yielded significantly lower estimates of mean number of drinks consumed when heavier than usual drinking days is included in the Summary measure (124.0 vs 147.0 drinks), mean number of days drugs were used (9.3 vs 10.7) and mean number of episodes of anal intercourse with a primary partner(1.2 vs 2.2). Differences generally remained significant when assessed by length of time between the study interview and last use of alcohol or drugs, with the exception of number of anal sex episodes with primary partners. Conclusions: These findings indicate that Timeline estimates are lower than estimates using a more standard method (Summary measures). Discrepancies between these findings and those reported by other researchers indicate a need for further exploration of the effects of the mode of administration on various populations.