Definitions of recovery and outcomes of major depression: results from a 10-year follow-up

Objective: Consensus operational definitions for symptomatic remission and recovery of a major depressive episode have been proposed but only irregularly followed. Method: We examined the predictive validity of different definitions of recovery in a multi-center 10-year follow-up study of an inception cohort of untreated unipolar major depressive episodes (n = 95). Time to recovery and time to recurrence after recovery were estimated by Kaplan-Meier survival analyses for alternative definitions requiring 2, 4, 6 or 12 months of remission to declare recovery. Results: The median time to recovery was 3.0, 4.0, 4.0 and 12.0 months respectively. The index episode lasted longer than 24 months in 9.4%, 9.2%, 12.6% and 24.5%. The median time to subthreshold recurrence was 16.0, 32.0, 42.0 and 74.0 months. Conclusion: Either 4- or 6-month duration of remission defined a change point before which the episode was continuous and after which the recurrence was reasonably unlikely.