Reconsidering the definition of Major Depression based on Collaborative Psychiatric Epidemiology Surveys

Diagnostic definitions for depressive disorders remain a debated topic, despite their central role in clinical practice and research. We use both recent evidence and nationally representative data to derive an empirically-based modification of DSM-IV/-5 Major Depressive Disorder (MDD).

A modified MDD diagnosis was derived by analyzing data from Collaborative Psychiatric Epidemiology Surveys, a multistage probability sample of adults (n=20 013; age ≥ 18 years) in coterminous USA, Alaska and Hawaii. The old and the newly suggested MDD definitions were compared for their associated disability (WHO Disability Assessment Schedule and number of disability days in past month), suicide attempt, and other covariates.

Our data-driven definition for major depression was "lack of interest to all or most things" plus four other symptoms from the set {weight gain, weight loss, insomnia, psychomotor retardation, fatigue, feelings of worthlessness, diminished ability to think/concentrate, suicidal ideation/attempt}. The new definition captured all the disability implied by MDD and excluded cases that showed no greater disability than the general population nor increased risk of suicide attempts. The lifetime prevalence of the new diagnosis was 14.7% (95% CI=14-15.4%) of the population, slightly less than for the old definition (16.4%; CI=15.4-17.3%).

Only conservative modifications of MDD could be studied, because of restrictions in the symptom data.

With only small adjusting, the new definition for major depression may be more clinically relevant than the old one, and could serve as a conservative replacement for the old definition.