Systemic lupus erythematosus increases the risks of deep vein thrombosis and pulmonary embolism: a nationwide cohort study

Background Studies on the risks of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients with systemic lupus erythematosus (SLE) are limited. We evaluated the effects of SLE on the risks of developing DVT and PE in a nationwide, population-based cohort study in Taiwan. Methods We randomly selected patients without SLE from the National Health Insurance database (N=23.74million), and frequency-matched four of them, on the basis of age, sex, and index year, to each SLE patient in the catastrophic illness registry of the NHI who was diagnosed with SLE between 1998 and 2008. Using a follow-up period ending in 2010, we analyzed the risks of DVT and PE with a Cox proportional-hazards regression analysis. Results The 13084 SLE patients (87.9% women; mean age of 35.6years) and 52336 controls were followed for 90237 and 379185 person-years, respectively. After adjustment for age, sex, and comorbidities, the SLE patients' risks of developing DVT and PE were 12.8-fold and 19.7-fold higher, respectively, than those of the comparison cohort. The risks of DVT and PE increased in both study groups when the data were stratified on the basis of sex, age, and comorbidities. The SLE patients aged <= 35years had the highest risks of developing DVT and PE. The multiplicative increased risks of DVT and PE were also significant in SLE patients with any comorbidity. Conclusion The risks of DVT and PE are significantly higher in SLE patients than in the general population.