Is prior course of illness relevant to acute or longer-term outcomes in depressed out-patients? A STAR*D report.

Background: Major depressive disorder (MDD) is commonly chronic and/or recurrent. We aimed to determine whether a chronic and/or recurrent course of MDD is associated with acute and longer-term MDD treatment outcomes.
Method: This cohort study recruited out-patients aged 18-75 years with non-psychotic MDD from 18 primary and 23 psychiatric care clinics across the USA. Participants were grouped as: chronic (index episode >2 years) and recurrent (n = 398); chronic non-recurrent (n=257); non-chronic recurrent (n=1614); and non-chronic non-recurrent (n = 387). Acute treatment was up to 14 weeks of citalopram (≤ 60 mg/day) with up to 12 months of follow-up treatment. The primary outcomes for this report were remission [16-item Quick Inventory of Depressive Symptomatology - Self-Rated (QIDS-SR(16)) ≤ 5] or response (≥ 50% reduction from baseline in QIDS-SR(16)) and time to first relapse [first QIDS-SR16 by Interactive Voice Response (IVR) ≥ 11].
Results: Most participants (85%) had a chronic and/or recurrent course; 15% had both. Chronic index episode was associated with greater sociodemographic disadvantage. Recurrent course was associated with earlier age of onset and greater family histories of depression and substance abuse. Remission rates were lowest and slowest for those with chronic index episodes. For participants in remission entering follow-up, relapse was most likely for the chronic and recurrent group, and least likely for the non-chronic, non-recurrent group. For participants not in remission when entering follow-up, prior course was unrelated to relapse.
Conclusions: Recurrent MDD is the norm for out-patients, of whom 15% also have a chronic index episode. Chronic and recurrent course of MDD may be useful in predicting acute and long-term MDD treatment outcomes.