Association between bullous pemphigoid and risk of venous thromboembolism: A nationwide population-based cohort study

Bullous pemphigoid (BP) has been reported to be associated with an increased risk of venous thromboembolism (VTE). However, the exact time course is unclear, and no previous studies have been reported in the Asian population. This nationwide population-based cohort study examined the risk of VTE among BP patients in Taiwan between 2007 and 2018. A total of 12 692 BP patients were 1:2 matched with non-BP patients by age, sex, and propensity score of comorbidities. Cumulative incidence and Cox proportional hazards models were used to investigate the risk of VTE. The BP cohort had a significantly higher VTE rate than the non-BP cohort (0.17% vs. 0.08%, p = 0.015) in 1 year; the finding was more prominent within the first 6 months after diagnosis. BP was a significant risk factor for VTE (hazard ratio [HR], 2.02; 95% confidence interval [CI], 1.01–4.06); the association mildly diminished but remained significant after extending the follow-up period to 2 years (HR, 1.73; 95% CI, 1.06–2.81). Other significant risk factors for VTE included cancer, chronic liver disease and cirrhosis, and female sex. In conclusion, this study revealed a 2.02-fold increased risk of VTE in patients with BP in Taiwan.