Examining the reliability of alcohol/drug use and HIV-risk behaviors using Timeline Follow-Back in a pilot sample

Research on the course of substance use disorders (SUDs) faces challenges in assessing behavior over lengthy time periods. Calendar-based methods, like the Timeline Followback (TLFB), may overcome these challenges. This study assessed the reliability of self-reported weekly alcohol use, drug use, and HIV-risk behaviors over the past 90 days using an interview TLFB. Individuals with SUD in outpatient treatment (N = 26) completed the TLFB at baseline and then a week later with separate interviewers. Weekly ratings were aggregated across 4 week intervals for each administration. Intra-class correlations were used to compare agreement between the two administrations. Reliabilities for alcohol and drug use ratings ranged from good to excellent for most drug categories (ICCs = 0.76 - 1.00), except opioid use (other than heroin) and sedative use produced sub-standard reliabilities (ICCs = 0.29 - 0.74). HIV-risk behavior reliabilities also ranged from good to excellent (ICCs = 0.70 - 0.97), but were substandard for the number of casual sex partners for some intervals (ICCs = 0.29, 0.63). Findings extend support for the use of TLFB to produce reliable assessments of many drugs and HIV-risk behaviors across longitudinal intervals.