Risk of Serious Infections in Patients with Bullous Pemphigoid: A Population-based Cohort Study

Patients with bullous pemphigoid are susceptible to serious infections, which are the leading cause of death in these patients. The aims of this population-based cohort study were to investigate the incidence and spectrum of serious infections in patients with bullous pemphigoid and to identify associated risk factors. The outcome measure was any infection requiring hospitalization. Hazard ratios with 95% confidence intervals were estimated using subdistribution hazard models. In total, 12,300 patients with bullous pemphigoid and 49,200 matched controls were identified through the National Health Insurance Research Database in Taiwan. Within 2 years of bullous pemphigoid diagnosis, 5,006 (40.7%) patients developed serious infections, with an incidence of 385.5/1,000 person-years. Patients with bullous pemphigoid were twice as likely to develop serious infections as controls (adjusted hazard ratio, 2.01; 95% confidence interval 1.92–2.10). Systemic corticosteroid use was the strongest risk factor, resulting in a 2-fold increase in the risk for serious infections. Other independent risk factors were advanced age, female sex, low income, and certain comorbidities. In conclusion, this study demonstrated an increased risk of serious infections following a diagnosis of bullous pemphigoid. Prophylaxis of serious infections through active intervention with the risk factors may be essential in reducing the morbidity and mortality associated with bullous pemphigoid. SIGNIFICANCE Infections were found to be common and severe following diagnosis of bullous pemphigoid. Patients with bullous pemphigoid were 3.3 times as likely to develop serious infections as those without bullous pemphigoid. Bullous pemphigoid per se doubled the risk of serious infections. Systemic corticosteroid use, the first-line therapy for bullous pemphigoid, was the strongest risk factor for serious infection in patients with bullous pemphigoid. Other independent risk factors associated with serious infections were advanced age, female sex, low income, and certain comorbidities. Prophylaxis of serious infections through active intervention with the risk factors might be essential in reducing the morbidity and mortality associated with bullous pemphigoid.