Rheumatoid arthritis increases the risk of deep vein thrombosis and pulmonary thromboembolism: a nationwide cohort study

Objective Studies on the association between rheumatoid arthritis (RA) and deep vein thrombosis (DVT) and pulmonary thromboembolism (PE) are scarce. This study identifies the effects of RA on the risks of developing DVT and PE in a nationwide prospective cohort study. Methods We studied the entire Taiwan population from 1998 to 2008, with a follow-up period extending to the end of 2010. We identified patients with RA using the catastrophic illness registry of the Taiwan National Health Insurance Research Database (NHIRD). We also selected a comparison cohort that was randomly frequency-matched by age (each 5-year span), sex and index year from the general population. We analysed the risks of DVT and PE using Cox proportional hazards regression models, including sex, age and comorbidities. Results From 23.74 million people in the cohort, 29 238 RA patients (77% women, mean age of 52.4 years) and 1 16 952 controls were followed 1 93 753 and 7 92 941 person-years, respectively. The risk of developing DVT and PE was 3.36-fold and 2.07-fold, respectively, in patients with RA compared with patients without RA, after adjusting for age, sex and comorbidities. The multiplicative increased risks of DVT and PE were also significant in patients with RA with any comorbidity. Conclusions This nationwide prospective cohort study demonstrates that DVT and PE risks significantly increased in patients with RA compared with those of the general population.