A simpler definition of major depressive disorder

The DSM-IV symptom criteria for major depressive disorder (MDD) are somewhat lengthy, with many studies showing that treatment providers have difficulty recalling all nine symptoms. Moreover, the criteria include somatic symptoms that are difficult to apply in patients with medical illnesses. In a previous report, we developed a briefer definition of MDD that was composed of the mood and cognitive symptoms of the DSM-IV criteria, and found high levels of agreement between the simplified and full DSM-IV definitions. The goal of the present study was to replicate these findings in another large sample of psychiatric out-patients and to extend the findings to other patient samples.

We interviewed 1100 psychiatric out-patients and 210 pathological gamblers presenting for treatment and 1200 candidates for bariatric surgery. All patients were interviewed by a diagnostic rater who administered a semi-structured interview. We inquired about all symptoms of depression for all patients.

In all three samples high levels of agreement were found between the DSM-IV and the simpler definition of MDD. Summing across all 2510 patients, the level of agreement between the two definitions was 95.5% and the kappa coefficient was 0.87.

After eliminating the four somatic criteria from the DSM-IV definition of MDD, a high level of concordance was found between this simpler definition and the original DSM-IV classification. This new definition offers two 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.