A comparison of the three year course between chronic depression and depression with multiple vs. few prior episodes

This study tested the hypothesis that chronic depression (CD) is more similar to depression with multiple prior episodes (ME) than to depression with few prior episodes (FE). Data from participants (n = 1013) with mild to moderate depressive symptoms (Patient Health Questionnaire [PHQ-9] score 5 - 14) who took part in a randomized control trial of an internet intervention for depression (EVIDENT trial) were re-analyzed. The MINI-interview was conducted to diagnose CD (n = 376). If CD was not diagnosed, the self-reported number of depressive episodes was used to categorize participants as having episodic depression with up to five (FE, n = 422) or more than five (ME, n = 215) prior episodes. Over a three-year period, participants were assessed repeatedly regarding the course of depression (PHQ-9, QIDS), quality of life (SF-12) and therapeutic progress (FEP-2). At baseline, most scores were different between CD and FE but comparable between CD and ME. Time to remission did not differ between CD and ME but was longer in CD compared to FE. Results suggest that ME closely resembles CD and that CD differs from FE.