Validity of a simpler definition of major depressive disorder

In previous reports from the Rhode Island Methods to Improve Diagnostic Assessment and Services project, we developed a briefer definition of major depressive disorder (MDD), and found high levels of agreement between the simplified and DSM-IV definitions of MDD. The goal of the present study was to examine the validity of the simpler definition of MDD. We hypothesized that compared to patients with adjustment disorder, patients with MDD would be more severely depressed, have poorer psychosocial functioning, have greater suicidal ideation at the time of the intake evaluation, and have an increased morbid risk for depression in their first-degree family members.

We compared 1,486 patients who met the symptom criteria for current MDD according to either DSM-IV or the simpler definition to 145 patients with a current diagnosis of adjustment disorder with depressed mood or depressed and anxious mood.

The patients with MDD were more severely depressed, more likely to have missed time from work due to psychiatric reasons, reported higher levels of suicidal ideation, and had a significantly higher morbid risk for depression in their first-degree family members. Both definitions of MDD were valid.

The simpler definition of MDD was as valid as the DSM-IV definition. This new definition offers two advantages over the DSM-IV definition-it is briefer and therefore more likely to be recalled and applied in clinical practice, and it is free of somatic symptoms thereby making it easier to apply with medically ill patients.