Duration of untreated depression influences clinical outcomes and disability.

Background: The duration of untreated depression (DUD) might have a substantial impact on the clinical outcomes; however, there are important knowledge gaps including the effects on disability and potential differences between first-episode and recurrent episodes of depression.

Methods: We recruited 121 outpatients with first episode and recurrent major depression, and conducted prospective clinical assessments over six months. Clinical outcomes included response to antidepressant therapy, remission and changes in disability.

Results: Patients with a DUD of six months or shorter were more frequently young, unemployed and had higher levels of physical illnesses than those with a longer DUD (all p<0.05). A shorter DUD was associated with significantly higher odds of response at 12 weeks (adjusted odds ratio 2.8; 95% CI: 1.2-6.8) and remission at 24 weeks (4.1; 95% CI: 1.6-10.5) after adjusting for relevant confounders. Changes in disability ratings were analyzed with growth curve analysis and showed steeper declines among those with a shorter DUD. The associations of DUD on clinical outcomes were evident both in patients with first-episode and recurrent depression.

Limitations: Naturalistic design. Self-rated assessment of disability. Findings from subgroup analyses should be replicated in larger sample size.

Conclusions: A shorter duration of untreated depression is associated with more favorable outcomes for major depression, including depression-related disability. This association seems to work both at the first and recurrent episodes, which might have direct implications for both primary and secondary prevention.