To investigate risk factors for acute coronary syndrome (ACS) in patients with new-onset rheumatoid arthritis (RA).
We performed a nested case-control study of patients with incident RA included in the Epidemiological Investigation of RA study. Cases with ACS were identified using Swedish national health registers and matched with up to 5 controls without ACS, based on incidence density-based sampling. Information on potential exposures (clinical disease activity, serologic features, genetic markers, comorbidities, pharmacotherapies, and sick leave) was collected from medical charts and register-based sources.
We identified 138 cases and 624 controls. Smoking, history of myocardial infarction, and >50 days of sick leave the year following RA onset were associated with an increased risk of ACS. Area under the curve measurements of C-reactive protein level, erythrocyte sedimentation rate, Disease Activity Score in 28 joints (DAS28), and global health in the upper tertile during the first year and the complete followup period were both strongly associated with an increased risk of ACS. Treatment with disease-modifying antirheumatic drugs did not alter the ACS risk, nor did the presence of rheumatoid factor (RF) or shared epitope alleles, whereas high anti-citrullinated protein antibody (ACPA) levels were borderline significantly associated with ACS risk.
In this study of risk factors for ACS in incident RA, clinical markers of inflammatory activity, disease activity, and total number of days of sick leave and disability pension during the first year following RA onset were identified as ACS risk factors. We found no association with RF, which was previously linked to cardiovascular disease risk in RA, but there was a borderline significant association with high ACPA levels.