SELF-REPORT AND OBSERVER MEASURES OF SUBSTANCE-ABUSE AMONG HOMELESS MENTALLY-ILL PERSONS IN THE CROSS-SECTION AND OVER TIME

The comparability of self-report and observer measures of substance ab use among 118 homeless mentally ill persons was assessed using cross-s ectional and longitudinal measures. Possible correlates of nondisclosu re were identified from demographic variables and clinical indicators. Lifetime abuse reported at baseline was a sensitive predictor of subs equent abuse. behavior in the project, but cross-sectional measures ba sed only on self-report or observer ratings failed to identify many ab users. A total of 17% of the subjects never disclosed abuse that was o bserved during the project. The level of substance abuse is likely to be severely underestimated among homeless mentally ill persons when on ly one self-report measure is used at just one point in time. This pro blem can, however, largely be overcome by incorporating information fr om observers and from multiple follow-ups or by focusing on Lifetime r ather than current abuse. We also conclude that underreporting may bia s estimates of some correlates of substance abuse.