Incidence, prevalence, and mortality of bullous pemphigoid in England 1998-2017: a population-based cohort study.

BACKGROUND: A rising incidence and high mortality were found for bullous pemphigoid over a decade ago in the UK. Updated estimates of its epidemiology are required to understand the healthcare needs of an ageing population. OBJECTIVES: To determine the incidence, prevalence, and mortality rates of bullous pemphigoid in England from 1998 to 2017. METHODS: We conducted a cohort study of longitudinal electronic health records using the Clinical Practice Research Datalink and linked Hospital Episode Statistics. Incidence was calculated per 100,000 person-years and annual point prevalence per 100,000 people. Multivariable analysis was used to determine incidence rate ratios by sociodemographic factors. Mortality was examined in an age-, sex-, and practice-matched cohort, using linked Office of National Statistics death records. Hazard ratios (HRs) were stratified by matched set. RESULTS: The incidence was 7.63 (95%CI 7.35 to 7.93)/100,000 person-years and rose with increasing age, particularly for elderly men. The annual increase in incidence was 0.9% (95%CI 0.2 to 1.7). The prevalence almost doubled over the observation period, reaching 47.99 (95%CI 43.09 to 53.49)/100,000 people and 141.24 (95%CI 125.55 to 158.87)/100,000 people over the age of 60. The risk of all-cause mortality was highest in the two years after diagnosis (HR 2.96; 95%CI 2.68 to 3.26), and remained raised thereafter (HR 1.54; 95%CI 1.36 to 1.74). CONCLUSIONS: We report a modest increase in the incidence rate of bullous pemphigoid, but show that the burden of disease in the elderly population is considerable. Mortality is high, particularly in the first two years after diagnosis.