Results from 2 longitudinal cohort studies conducted in South Korea indicate a significantly increased risk for depression among patients with rheumatoid arthritis (RA), with women and those >30 years of age displaying the highest rates. This is according to an article published in Rheumatology.
Investigators abstracted data from the Korean Health Insurance Review and Assessment Service – National Sample Cohort (HIRA-NSC) from the years 2002-2013. The HIRA-NSC is a population-based cohort established by the National Health Insurance Service of South Korea. HIRA-NSC queries demographics, health, and diagnostic data from >1 million individuals randomly selected from South Korea’s National Health Insurance Database.
The present analyses included data from 114,369,638 medical claims filed by 1,125,691 patients. Patients with depression and/or RA were identified through their respective International Statistical Classification of Diseases version 10 (ICD-10) codes. Two studies were designed. Study I matched patients with depression 1:4 with cohort members without depression. Study matched patients with RA 1:4 with cohort members without RA. Matching in both studies was performed for age group, sex, income bracket, and region of residence. Cox proportional hazards models were used to calculate hazard ratios (HRs) for depression and RA in each study. HR calculations were adjusted for number of comorbidities.
Study I enrolled a total of 38,087 patients with depression and 152,348 individuals in a control group. A greater proportion of the patients with depression (n=1260; 0.7%) had a diagnosis of RA compared with the control group (n=883; 0.6%) (P =.02). However, the HR for RA was not significantly elevated in the depression group compared with the control group.
Study II enrolled a total of 7385 patients with RA and 29,540 individuals in a control group, of whom 408 (5.5%) and 1246 (4.3%) had a diagnosis of depression, respectively (P <.001). Patients with RA had significantly increased risk for depression compared to those in the control group without RA (HR, 1.20; 95% CI, 1.07-1.34; P =.002). In subgroup analyses, patients with RA over 30 years of age had the greatest HRs for depression compared with their control subgroups.
Specifically, patients with RA aged 30-59 years (HR, 1.17; 95% CI, 1.01-1.36; P =.036) and patients ≥60 years (HR, 1.29; 95% CI, 1.08-1.55; P =.006) had significantly elevated risk for depression compared to controls in the same age brackets. Women with RA, unlike men, also displayed significantly higher depression risk compared with controls of the same gender (HR, 1.19; 95%, 1.05-1.35; P =.006).
These results suggest that while RA increases the risk for depression, this association is not bidirectional. Women with RA and patients >30 years were particularly susceptible to depression. Of note, data on RA and depression severity were not available, nor were data on smoking, alcohol consumption, or physical activity. As such, analyses may not have accounted for all possible factors contributing to depression. Even so, the elevated HRs for depression observed among RA subgroups emphasize the need for mental health care access for patients with RA.
Kim SY, Chanyang M, Oh DJ, Choi HG. Association between depression and rheumatoid arthritis: two longitudinal follow-up studies using a national sample cohort [published online November 19, 2019]. Rheumatology (Oxford). doi:10.1093/rheumatology/kez559