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 100 000 person-years and annual point prevalence per 100 000 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 center dot 63 [95% confidence interval (CI) 7 center dot 35-7 center dot 93] per 100 000 person-years and rose with increasing age, particularly for elderly men. The annual increase in incidence was 0 center dot 9% (95% CI 0 center dot 2-1 center dot 7). The prevalence almost doubled over the observation period, reaching 47 center dot 99 (95% CI 43 center dot 09-53 center dot 46) per 100 000 people and 141 center dot 24 (95% CI 125 center dot 55-158 center dot 87) per 100 000 people over the age of 60 years. The risk of all-cause mortality was highest in the 2 years after diagnosis (HR 2 center dot 96; 95% CI 2 center dot 68-3 center dot 26) and remained raised thereafter (HR 1 center dot 54; 95% CI 1 center dot 36-1 center dot 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. What is already known about this topic? Bullous pemphigoid (BP) is a blistering skin disorder which typically affects the elderly. BP poses a high burden on affected patients and has significant healthcare costs. The burden of disease in the UK was estimated over a decade ago and found to have a rising incidence and high mortality. What does this study add? The incidence of BP in England was 7 center dot 63 (95% CI 7 center dot 35-7 center dot 93) per 100 000 person-years between 1998 and 2017. The burden of BP in the elderly population is substantial and it should not be considered a rare disease in these age groups. The risk of death was almost three times higher in the first 2 years after a diagnosis of BP compared with people without the disease and remained raised thereafter.