Influence of psychoactive substance use on the reliability of psychiatric diagnosis.

The interrater reliability of diagnoses made on the basis of a structured interview for psychiatric patients with and without psychoactive substance use disorders (PSUDs) was examined. Forty-seven pairs of ratings by 9 different clinical interviewers were used. Results supported 3 major findings: (a) The interrater reliability for non-PSUD psychiatric diagnoses is quite high when a subject has no diagnosable PSUD; it is lower, though still substantial, when a PSUD is present. (b) Interviewers are not aware of this and are just as certain of the accuracy of their diagnoses when a PSUD is present as when one is not. (c) Interrater reliability is moderate to substantial as to the judgment of whether, when a non-PSUD diagnosis is present, it is caused by the use of psychoactive substances. The implications of these findings for the appropriate selection of treatments for dually diagnosed patients are discussed.