Background: Few studies have addressed the implication of the duration of untreated illness (DUI) on the clinical outcome of mood disorders. Although not focusing on DUI, previous findings suggest that the longer it takes to start appropriate treatment, the worse will be the evolution of depressive disorder. We sought to determine the effect of the duration of untreated episode (DUE) on 1) rates of response to treatment, 2) time to attain a sustained response and 3) rates of remission of MDD, dealing specially with first-depressive episodes.
Methods: 141 patients with MDD were grouped into long DUE (>8 weeks) and short DUE (< or =8). Statistical analyses were performed to determine differences in outcome variables. The same analyses were repeated by splitting the sample between first-episode and recurrent depression.
Results: The percentage of patients who achieved a sustained response was significantly higher in the group with a short DUE [OR=2.6; 95% CI 1.3-5.1]. Survival analyses showed that patients with a long DUE delayed longer time to attain a sustained response [39 vs. 20 days, p=0.012]. Once the sample was split, these results were even more pronounced in the subsample of first-depressive episode patients.
Limitations: Given that the sample was originally recruited for two clinical trials, the follow-up period of this study is only six weeks long.
Conclusions: Our results indicate that response to antidepressant treatments is faster when the no-treatment interval is reduced. The earliest treatment of first-depressive episodes seems to be crucial since a shorter duration of untreated illness implies better response outcomes.