Interactive effects of systemic inflammation and life stressors on treatment response of depressive disorders.

Inflammation is an important contributor in the pathophysiology of depression and recent evidence suggests that systemic inflammation and life stressors have interactive roles in depression onset. The aim of the present study was to investigate the individual and interactive effects of systemic inflammation and life stressors with short- and long-term treatment responses in outpatients with depressive disorders in a naturalistic one-year prospective design. Serum high-sensitivity C-reactive protein (hsCRP) levels were measured and number of stressful life events (SLEs) during the last 3 months were ascertained from 1094 patients at baseline. These patients received initial antidepressant monotherapy, then, for patients with an insufficient response or uncomfortable side effects, next treatment with alternative strategies were administered at every 3 weeks in the acute treatment phase (3, 6, 9, and 12 weeks) and at every 3 months in the continuation treatment phase (6, 9, and 12 months). 12-week and 12-month remission was estimated, defined as a Hamilton Depression Rating Scale score of ≤ 7. In multivariable logistic regression analyses, individual effects were found only between higher baseline serum hsCRP levels (≥ 1.0 vs. < 0.1 mg/L) and 12-week non-remission. Significant interactive effects between higher hsCRP levels and higher number of SLEs (≥ 2 vs. < 2) on both 12-week and 12-month non-remission were observed. Combining serum hsCRP levels and number of SLEs might therefore be a useful predictor for short- and long-term treatment responses in patients with depressive disorders receiving pharmacotherapy.