A scale to screen for DSM-IV axis I disorders in psychiatric out-patients: performance of the psychiatric diagnostic screening questionnaire

Background. The Psychiatric Diagnostic Screening Questionnaire (PDSQ) is a reliable and valid self-report scale designed to screen for the most common DSM-IV Axis I disorders encountered in out-patient mental health settings. The present report is the second large-scale validation study of the PDSQ in psychiatric out-patients. Because some of the sizes of the diagnostic groups in the initial report were modest, it is important to determine whether the recommended cut-off scores to screen for psychiatric disorders remained the same in a replication study. Method. Six hundred and seventy psychiatric out-patients presenting for treatment were evaluated with a semi-structured diagnostic interview after completing the PDSQ. Results. Based on receiver operating curve analysis, the PDSQ performed as well in the replication sample as in the initial validation study. For nine of the 13 PDSQ subscales the recommended cutoff score in the replication study was the same as in the initial study. After combining the data from the two studies (n = 1300) the mean sensitivity across the 13 PDSQ subscales was 87 % and the mean negative predictive value was 97%. Conclusions. The PDSQ is a diagnostic aid designed to improve the efficiency of conducting initial diagnostic evaluations. From a clinical perspective it is important that a screening tool have good sensitivity so that most cases are detected, and high negative predictive value so that most non-cases on the measure are indeed non-cases. The results of this second large validation study indicate that most of the PDSQ subscales achieved this goal.