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 (BP) 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 BP 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 100000 person-years and annual point prevalence per 100000 people. Multivariate 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% confidence interval (CI) 7·35–7·93] per 100000 person-years and rose with increasing age, particularly for elderly men. The annual increase in incidence was 0·9% (95% CI 0·2–1·7). The prevalence almost doubled over the observation period, reaching 47·99 (95% CI 43·09–53·46) per 100000 people and 141·24 (95% CI 125·55–158·87) per 100000 people over the age of 60 years. The risk of all-cause mortality was highest in the 2 years after diagnosis (HR 2·96; 95% CI 2·68–3·26) and remained raised thereafter (HR 1·54; 95% CI 1·36–1·74). Conclusions: We report a modest increase in the incidence rate of BP, but show that the burden of disease in the elderly population is considerable. Mortality is high, particularly in the first 2 years after diagnosis