An increase in C-reactive protein levels during antidepressant treatment predicts treatment non-response in major depressive disorder

BackgroundOne-third of patients with major depressive disorder (MDD) exhibit low-grade inflammation as reflected by C-reactive protein (CRP) concentrations > 3 mg/L. We explored whether CRP changes from baseline to week one of antidepressant treatment ({Delta}CRP) can serve as a marker of treatment response. MethodsCRP plasma levels were measured at baseline and after the first week of treatment in 33 MDD patients and correlated with patients Hamilton depression scale (HAM-D), while adjusting for age, gender and body mass index. The early and final antidepressant responses were defined as a > 25% and > 50% HAM-D score reduction at week one and four of treatment compared to baseline, respectively. We compared baseline and week-one CRP levels with the paired t-test within responders and non-responders separately and {Delta}CRP between the groups with the ANCOVA. ResultsHigher {Delta}CRP correlated with lower final {Delta}HAM-D scores (r = -0.5, p = 0.006). Non-responders showed higher {Delta}CRP - but not baseline and week one CRP - than responders (p = 0.018, Cohens d = 1.1). A {Delta}CRP increase was observed in 13/16 (81%) non-responders and 7/17 (41%) responders (Fishers exact tests p = 0.03). A {Delta}CRP increase combined with an early non-response was observed in 13/16 (81%) non-responders and 1/17 (6%) responders (p < 0.0001). ConclusionsRather early {Delta}CRP at week one than baseline CRP might be indicative of treatment response at week four, especially if combined with early {Delta}HAM-D. In the future, {Delta}CRP could be introduced into psychiatric practice to guide treatment plans.