Untreated duration predicted the severity of depression at the two-year follow-up point

Background: No study has investigated the impact of the duration of untreated depression (DUD) on the severity of depression at the two-year follow-up point in patients with major depressive disorder (MDD) who discontinued pharmacotherapy. This study aimed to investigate this issue. Methods: This study enrolled 155 subjects with MDD at baseline, and 101 subjects who had discontinued pharmacotherapy for 17.1 ± 5.8 months were assessed at the two-year follow-up point. DUD was defined as the interval between the onset of the index major depressive episode and the start of pharmacotherapy. The 17-item Hamilton Depression Rating Scale (HAMD) was used to evaluate depression. Multiple linear regressions were used to examine the impacts of DUD on the severity and improvement percentage (IP) of depression at follow-up. Results: A longer DUD was significantly associated with a greater severity and a lower IP of depression at follow-up. After controlling for confounding factors, DUD was the most significant factor predicting the severity and IP of depression at follow-up. DUD was more strongly associated with the prognosis of depression at follow-up than depression and anxiety severities at baseline. Conclusions: The DUD at baseline independently predicted the severity of depression at the two-year follow-up point. Although the patients had discontinued pharmacotherapy for nearly 1.5 years, the impact of the DUD on the severity of depression persisted at follow-up. The DUD was an important index that predicted the severity of depression at the two-year follow-up point.