Risk of New-Onset Acute Coronary Syndrome and Atrial Fibrillation in Patients With Rheumatoid Arthritis Compared With a Risk-Set and Propensity Score-Matched Cohort　― A Nationwide Cohort Study ―

BACKGROUND: Rheumatoid arthritis (RA) has extra-articular manifestations of cardiovascular diseases and is associated with a high mortality rate in Western populations. This study aimed to investigate the risk of acute coronary syndrome (ACS) and atrial fibrillation (AF) associated with RA in a Korean population. METHODS AND RESULTS: Patients were selected from a senior cohort from the Korean National Health Insurance Service in 2002, and followed until 31 December 2015. Patients with newly developed ACS and AF were identified and compared with controls for a 10-year period using time-dependent propensity and risk-set matching. A total of 4,217 incident RA patients and their 8,432 controls comprised the incident RA and matched cohorts, respectively. ACS was identified during 24,642 person-years [incidence rate (IR) 402 per 10,000 person-years, 95% confidence interval (CI) 330-489] among the RA cohort. In the matched cohort, 141 ACS patients were identified during 50,011 person-years (IR 282 per 100,000 person-years, 95% CI 239-333). RA patients were 1.43-fold more likely to develop ACS than the matched controls [hazard ratio (HR) 1.43, 95% CI 1.10-1.84], but showed similar occurrence risk of AF (HR 1.06, 95% CI 0.83-1.35). CONCLUSIONS: A higher risk for ACS and a similar risk for AF were found by risk-set matched analysis in a senior RA cohort compared with the control, using Korean nationwide long-term data.