A New Empirical Definition of Major Depressive Episode Recovery and Its Positive Impact on Future Course of Illness

Abstract

Objective: To provide the first head-to-head test of the predictive validity of 2 resolution levels included in the current consensus definition of major depressive episode (MDE) recovery and provide an empirically based, clinically useful definition of the end of an MDE.

Method: 322 participants entering the National Institute of Mental Health Collaborative Depression Study with MDE (diagnosed by Research Diagnostic Criteria) in 1978-1981, and followed thereafter for up to 31 years, were divided into those with 8 consecutive weeks of asymptomatic MDE recovery or residual subsyndromal depressive symptom (SSD) resolution of their index MDE. These 2 levels of recovery were defined based on weekly symptom status on all depressive conditions, assessed by Longitudinal Interval Follow-Up Evaluation (LIFE) interviews conducted every 6 months. Primary measures of validity of these 2 alternative definitions were first well interval duration and long-term depressive illness burden. Groups were also compared on clinical variables, antidepressant treatment, and psychosocial function.

Results: 61.2% of subjects recovered asymptomatically from their index MDE. By survival analysis, they remained free of a depressive episode relapse or recurrence 4.2 times longer than those with SSD resolution (median = 135 vs 32 weeks; χ² = 70.65; P < .0001). This was not attributable to a difference in intensity of antidepressant medication. Compared to asymptomatic recovery, SSD resolution was associated with significantly longer and more severe index MDEs, with more miscellaneous psychopathology as well as increased long-term psychosocial dysfunction and a greater depressive illness burden during the ensuing 10 or 20 years. Asymptomatic MDE resolution was a stronger predictor of time well than any of 18 other predictors, singly or combined. Eight consecutive weeks of asymptomatic recovery had 93% overlap with a 4-week definition and conferred little benefit over 4 weeks.

Conclusions: Four consecutive weeks of asymptomatic recovery defines the end of an MDE and the beginning of a stable well state with improved psychosocial function. Residual symptom resolution is a continuation of an active state of the episode, not the end of an MDE.