Factors affecting agreement between severely mentally ill alcohol abusers' and collaterals' reports of alcohol and other substance abuse.

This study examined subject-collateral reports of alcohol use among a sample of 167 dually diagnosed individuals seeking outpatient treatment at a community mental health clinic. All subjects met Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) criteria for a schizophrenia-spectrum or bipolar disorder and for alcohol abuse or dependence. Subjects were recruited within 2 weeks of treatment entry and completed measures of cognitive functioning, alcohol dependence severity, psychiatric symptoms, and quantity and frequency of substance use over the previous 60 days using the Timeline Follow-Back interview (L. C. Sobell & M. B. Sobell, 1996). They also provided a urine sample, which was screened for recent drug use. Collateral interviews were conducted by phone and included an assessment of the subject's alcohol and drug use over the same 60-day period. Collaterals also reported their confidence in the accuracy of their reports. Overall, the results indicated generally poor subject-collateral agreement. However, subject-collateral agreement appeared better for those individuals (n = 97) with negative urine drug screens. The most consistent predictor of subject-collateral discrepancy scores was subjects' recent drug use. Recommendations for enhancing the validity of self-reports of substance use in a severely mentally ill population are discussed.