Association between use of Chinese herbal medicine and depression risk in patients with rheumatoid arthritis: A nationwide retrospective cohort study

Aim: Depression is a common mental disorder in rheumatoid arthritis (RA) patients and may provoke the onset of poor clinical prognoses. In view of this, whether or not the use of Chinese herbal medicines (CHMs) can alleviate the risk of depression still remains unclear. We conducted a longitudinal cohort study to evaluate the association between CHMs us and depression risk among RA patients. Method: Using claims data from the National Health Insurance of Taiwan, we identified 6609 newly diagnosed RA patients aged 20 years or older between 1998 and 2010. From this sample, we recruited 3386 CHM users and randomly selected 3223 controls using propensity scores matching from the remaining cases as the non-CHMs users. They were followed until the end of 2012 to record depression incidence. A Cox proportional hazards regression model was used to compute the hazard ratio (HR) of depression with regard to the use of CHMs. Results: During the 15-year follow-up, 249 CHM users and 314 non-CHM users developed depression, representing an incidence rate of 9.33 and 14.98, respectively, per 1000 person-years. We found that use of CHMs was associated with lower risk of depression by 38% (95% confidence interval 0.54-0.76). The most predominant effect was observed in those receiving CHMs for over 2 years (adjusted HR 0.34). Seven commonly prescribed CHMs could lessen the risk of depression: Chuan-niu-xi, Jie-geng, San-qi, Jia-wei-xia-yao-san, Dang-gui-nian-tong-tang, Zhi-gan-cao-tang, and Suan-zao-ren-tang. Conclusion: This study supports that adding CHMs into conventional therapy may prevent subsequent depression risk for RA patients.