Utility of Collateral Information in Assessing Substance Use Among Psychiatric Outpatients

Purpose. This study addressed the utility of collateral informants for validating self-reported substance use by psychiatric outpatients. Methods. Participants were 92 men and women with severe and persistent Axis I disorders, attending outpatient programs at a public psychiatric facility. As part of a substance use assessment, each participant identified a collateral who would provide information about the participant's substance use in the last month. The collaterals consisted of family (35%), peers (23%), and others (40%) who were primarily mental health staff. Results. Comparisons of participant and collateral reports showed high percent agreement with significant but modest measures of association. The likelihood that collateral reports will have information value (i.e., corroborate or exceed self-reports) was greater when the topic is illicit drug use and the frequency of contact is once a week or more. In this sample, siblings were more likely to be uninformative than other types of collaterals, whereas treatment staff were comparable to other types of collaterals in the information value of their corroborative reports. Overall, the collateral reports rarely provided more information than was provided by the participants themselves. Implications. This pattern is consistent with the pattern observed in non-psychiatric samples and supports the accuracy of self-reported substance use by psychiatric outpatients.