Cancer is not a risk factor for bullous pemphigoid: 10-year population-based cohort study.

ABSTRACT

BACKGROUND: Bullous pemphigoid (BP) is the most common autoimmune bullous disease. Whether there is an increased risk for subsequent BP among patients with cancer is still unclear. OBJECTIVES: To evaluate the risk for subsequent BP in patients with cancer. METHODS: This nationwide population-based cohort study was based on data obtained from the Taiwan National Health Insurance Database between 2000 and 2011. A total of 36 838 patients with cancer and 147 352 age-, sex- and index-date-matched controls were recruited. The hazard ratio (HR) of subsequent BP in the patients with cancer was analysed using a Fine-Gray competing risk regression model with mortality as the competing event. RESULTS: The incidence of BP per 100 000 person-years was 17·2 in the patients with cancer and 19·8 in the controls; therefore, the crude incidence rate ratio was 0·87 [95% confidence interval (CI) 0·53-1·36]. The HR of subsequent BP in the patients with cancer was 0·47 (95% CI 0·23-0·94) using the Fine-Gray competing risk regression model. Age (HR 1·05, 95% CI 1·03-1·07), diabetes mellitus (HR 1·69, 95% CI 1·10-2·59) and cerebrovascular disease (HR 2·14, 95% CI 1·36-3·34) were independent risk factors for BP. CONCLUSIONS: The incidence of BP in patients with cancer was not higher than in the control group. Cancer is not a risk factor for BP.