Concordance between a simpler definition of major depressive disorder and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition: an independent replication in an outpatient sample

The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) symptom criteria for major depressive disorder (MDD) are somewhat lengthy with several studies showing that clinicians have difficulty recalling all 9 symptoms. Moreover, the criteria include somatic symptoms that are difficult to apply in patients with medical illnesses. To address these problems, a simpler definition of MDD was developed that did not include the somatic symptoms. Previous reports found high levels of agreement between the simplified and full DSM-IV definition of MDD. However, the same research group has conducted all previous studies of psychiatric patients. The goal of the present study was to determine if a high level of concordance between the 2 definitions would be replicated in an independent setting. We interviewed 2907 psychiatric outpatients presenting for treatment at the Boston University Center for Anxiety and Related Disorders. A trained diagnostic rater administered a semistructured interview and inquired about all symptoms of depression for all patients. A high level of agreement was found between the DSM-IV and the simpler definition of MDD. The absolute level of agreement between the 2 definitions was 95.5% and the κ coefficient was 0.88. Thus, consistent with previous studies, a high level of concordance was found between a simpler definition of MDD and the DSM-IV definition. This new definition offers 2 advantages over the current DSM-IV definition—it is briefer, and it is easier to apply with medically ill patients because it is free of somatic symptoms. Implications of these findings for DSM-5 are discussed.