Diagnosing major depressive disorder: II: is there justification for compound symptom criteria?

The DSM-IV symptom inclusion criteria for the diagnosis of major depressive disorder (MDD) are constructed in three ways: single symptom criteria, compound criteria encompassing opposite variants of the same disturbance, and compound criteria encompassing related problems. In the present report from the Rhode Island Methods to Improve Diagnostic Assessment and Services project, we tested the following three hypotheses: (1) the components of compound-opposite criteria rarely occur simultaneously, (2) the components of the compound-related criteria frequently occur simultaneously, and (3) the components of the compound-related criteria more frequently co-occur than other pairs of the MDD criteria. We also examined how many patients would be rediagnosed if the compound criteria were split into separate items. One thousand eight hundred psychiatric outpatients were evaluated with a semistructured diagnostic interview. We inquired about all of the DSM-IV diagnostic criteria for MDD for all patients. As hypothesized, the symptoms of the compound-opposite criteria usually did not co-occur, whereas the symptoms of the compound-related criteria frequently were present simultaneously. However, the results also indicated that other pairs of symptoms were as likely to co-occur, and were as strongly associated with each other, as the symptoms of the compound-related criteria. Thus, the findings provide mixed support for the assumptions hypothesized to underlie the composition of the DSM-IV criteria for MDD. When the compound criteria were subdivided and the diagnostic threshold for MDD was kept constant, only a small percentage of patients was reclassified from a noncase to a case. The implications of these results for constructing diagnostic criteria, and for developing measures to assess the severity of depression, are discussed.