Objective: The purpose of this study was to evaluate the test-retest reliability of the Timeline Followback (TLFB) interview for assessing daily alcohol and drug use with adults living with a severe mental illness.
Method: Participants were 132 psychiatric outpatients (64% men) with a confirmed schizophrenia-spectrum (52%) or major mood disorder (48%) and a lifetime history of substance use disorder. They completed a 90-day TLFB twice, separated by a mean of 5 days, and represented 55% of the participants who originally consented to be in the study.
Results: Test-retest reliability coefficients ranged from 0.73 to 1.00 (rounded) for 30-day TLFB and from 0.77 to 1.00 (rounded) for the 90-day TLFB. Within-subject comparisons of means across the three 30-day windows revealed no significant differences, and no degradation of the magnitude of the reliability coefficients was observed with increasingly distant assessment periods.
Conclusions: The TLFB is a reliable method of assessing alcohol and drug use in outpatients diagnosed with severe mental illness.