Evaluation of screens for mental disorders in primary care: methodological issues.

Several brief screens are available to help identify mental disorders in primary care. In choosing among them, an investigator must consider the clinical research setting, the sampling framework, and the strategy used to assess the reliability and validity of the instruments. These issues are considered in the context of the study that revised the Symptom-Driven Diagnostic System for Primary Care (SDDS-PC) for the DSM-IV. The sample size determination strategy used in that study rendered a sample that was large enough to allow for a split-sample approach to data analysis. The screen algorithms were developed on an index sample, and the operating characteristics were cross-validated with data from a separate sample. Standard operating characteristics as well as chance-corrected, or quality operating characteristics were used to evaluate the construct validity of the screens. Criterion-related validity of the screens was evaluated by examining functional impairment. Screens such as these may be valuable clinical and research tools for psychiatric diagnosis in primary care.