Background/Purpose: Prior population-based studies have shown an increased risk for cardiovascular complications in patients with SLE. However, the magnitude of the risk for venous thromboembolism (VTE) has not been well quantified in this patient group, particularly within the general population context. Our objective was to determine the risk of venous thromboembolism (VTE), pulmonary embolism (PE), and deep vein thrombosis (DVT) in individuals with incident systemic lupus erythematosus (SLE) in the general population.

Methods: Using the Health Information Network (THIN) database, a population database that includes 11.1 million patients, 6.2% of the population of the United Kingdom, we conducted a cohort study of all patients with incident SLE and up to 10 age-, sex-, and entry time-matched individuals from the general population. SLE patients were identified by read codes for systemic involvement of lupus, excluding cutaneous-only disease. We compared incidence rates of PE, DVT, and VTE between the two groups and within the SLE group according to SLE disease duration. We calculated hazard ratios (HRs), adjusting for potential confounders including the comorbidities stroke, myocardial infarction, kidney disease, and malignancy, the use of NSAIDs, aspirin, and glucocorticoids, and for smoking status.

Results: Among 1494 individuals with SLE (87.1% female, mean age 50 years), there were 13 cases of DVT and 14 of PE. Among the 10,473 individuals without SLE, there were 38 cases of DVT and 33 of PE. The incidence rates of PE, DVT, and VTE were 1.6, 1.4, and 2.9 per 1000 person-years in the SLE group, whereas the corresponding rates were 0.5, 0.6, and 1.1 per 1000 person-years among individuals without SLE. Compared with non-SLE individuals, the multivariable HRs among patients with SLE were 3.17 (95% CI, 1.65-6.10), 3.42 (95% CI, 1.72-6.81), and 3.14 (95% CI, 1.94-5.07) for PE, DVT and VTE, respectively. The age-, sex-, BMI-, and entry time-matched HRs for PE, DVT, and VTE were highest during the first year after SLE diagnosis: 14.30 (95% CI, 4.02-50.82), 8.70 (95% CI, 1.74-43.40), and 10.82 (95% CI, 3.91-29.90), respectively.

Conclusion: These findings provide population-based evidence that patients with SLE are at an increased risk of VTE, especially within the first year after SLE diagnosis. Increased monitoring for this potentially fatal outcome and its modifiable risk factors is warranted in this patient population, particularly early after disease onset.