Diagnosing major depressive disorder VI: performance of an objective test as a diagnostic criterion

Considerable research has evaluated biological and psychological tests for various psychiatric disorders; however, few objective tests are included in DSM-IV as diagnostic criteria. It was recently suggested that existing tests are insufficiently accurate to be included as diagnostic criteria. While it is true that there are limitations in the sensitivity and/or specificity of such tests, this should not rule them out as effective diagnostic criteria. Studies examining the diagnostic efficiency of the DSM criteria sets demonstrate that the individual criteria vary in their sensitivity and specificity. In the present article, we suggest that the same standard should be applied to the evaluation of objective tests. That is, we suggest changing the perspective used to evaluate the performance of biological and psychological measures from the traditional one examining them as diagnostic tests to one in which these measures are evaluated as diagnostic criteria. To our knowledge, no previous investigators have compared the psychometric performance of an objective test to the psychometric performance of the DSM-IV symptom criteria. The recent report from the committee to develop a research agenda for the initial planning phase for DSM-V discussed the use of self-report symptom scales as possible diagnostic criteria in nonpsychiatric settings. In the present report from the Rhode Island Methods to Improve Diagnostic Assessment and Services project, we examined the performance of a self-report depression questionnaire as a diagnostic criterion for major depressive disorder (MDD). We compared the performance of the Diagnostic Inventory for Depression to the performance of the DSM-IV MDD symptom criteria in 1138 psychiatric outpatients. The results indicated that the diagnostic efficiency of the Diagnostic Inventory for Depression was similar to the loss of interest or pleasure criterion, and superior to all of the remaining DSM-IV MDD symptom criteria except low mood. We discuss issues related to the possible use of a self-administered depression symptom scale as a diagnostic criterion.