Risk of venous thromboembolism in patients with rheumatoid arthritis.

Abstract

Rheumatoid arthritis (RA) is associated with cardiovascular disease (CVD), but little is known about its association with another form of vascular disorder, venous thromboembolism (VTE). A retrospective cohort study was conducted using US insurance claims. RA and non-RA patients were matched on age, sex, and index date. Incidence rates (IRs) and rate ratios (RRs) of VTE, defined as the composite of deep vein thrombosis (DVT) or pulmonary embolism (PE), were calculated. Cox proportional hazards models compared VTE risks between RA and non-RA patients, adjusting for VTE risk factors such as CVD, surgery, hospitalization, medications, and acute-phase reactants. Over the mean followup of 2 years, the IR for VTE among RA patients was 6.1 per 1,000 person-years, 2.4 times higher (95% confidence interval [95% CI] 2.1-2.8) than the rate of non-RA patients. The IRs for both DVT (RR 2.2, 95% CI 1.9-2.6) and PE (RR 2.7, 95% CI 2.2-3.5) were higher in RA patients compared with non-RA patients. After adjusting for risk factors of VTE, the VTE risk remained elevated in RA patients (hazard ratio 1.4, 95% CI 1.1-1.7) compared to non-RA patients. The result was similar after further adjustment for elevated acute-phase reactants (hazard ratio 1.5, 95% CI 0.3-6.5). One-third of patients who developed VTE had at least 1 major VTE risk factor 90 days before and after the VTE event. Our results showed an increased risk of developing VTE for RA patients compared with non-RA patients. The risk was attenuated but remained elevated even after adjusting for various risk factors for VTE.