Incidence prevalence and mortality of bullous pemphigoid in
Incidence, prevalence, and mortality of bullous pemphigoid in England 1998 -2017: a population -based cohort study MSM PERSSON 1, KE HARMAN 1, Y VINOGRADOVA 1, SM LANGAN 2, J HIPPISLEYCOX 3, KS THOMAS 1, S GRAN 1 1 UNIVERSITY OF NOTTINGHAM 2 LONDON SCHOOL OF HYGIENE AND TROPICAL MEDICINE 3 UNIVERSITY OF OXFORD British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Lead Researcher Monica SM Persson Research Fellow Centre of Evidence Based Dermatology University of Nottingham British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Introduction What’s already known? Bullous pemphigoid is a blistering skin disorder which typically affects the elderly Bullous pemphigoid 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 a rising incidence and high mortality British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Objective To determine the incidence, prevalence, and mortality rates of bullous pemphigoid in England from 1998 to 2017 British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Methods Data sources - Routinely collected healthcare data from England: Clinical Practice Research Datalink (CPRD) primary care data Hospital Episode Statistics (HES) Admitted Patient Care inpatient data Office of National Statistics (ONS) mortality data Observation period – January 1998 to December 2017 Study population – Adult men and women British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Methods Incidence Outcome - bullous pemphigoid Incidence rates per 100, 000 person-years Poisson regression – adjusted incidence ratios for age, calendar period, sex, ethnicity, region, and index of multiple deprivation Prevalence Outcome – bullous pemphigoid Prevalence per 100, 000 people on 31 st of July of each calendar year British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Methods Mortality Design – matched longitudinal cohort (4 disease-free controls, matched by age, sex, and general practice) Outcome – date of death Survival described with Kaplan-Meier technique All-cause mortality compared with Cox proportional hazards regression stratified by matched set British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Results - incidence Overall incidence rate: 7. 63 (95%CI 7. 35 to 7. 93) per 100, 000 person-years Incidence has increased by 0. 9% per calendar year Figure Crude incidence rate of bullous pemphigoid per 100, 000 person -years by age category Shown separately for men and women, with upper and lower limits of 95%CI British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Results - prevalence Figure Point prevalence of bullous pemphigoid on 31 st of July of each calendar year, per 100, 000 people. Shown for all adults and for people aged over 60 years Shading indicates the upper and lower limits of the 95%CI 141. 2 (95%CI 125. 6 to 158. 9) in 2017 48. 0 (95%CI 43. 1 to 53. 5) in 2017 26. 8 (95%CI 23. 8 to 30. 2) in 1998 British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Results - mortality Hazard ratio: 2. 96 (95%CI 2. 68 to 3. 26) in the first two years after diagnosis 1. 54 (95%CI 1. 36 to 1. 74) thereafter Figure Kaplan-Meier curve for patients with and without bullous pemphigoid, showing mortality over time since index date British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Discussion – main findings The incidence of bullous pemphigoid is highest in older people, particularly older men Incidence of bullous pemphigoid has increased by 0. 9% per year in the last two decades Using the European definition of a rare disease (prevalence < 50 per 100, 000) – bullous pemphigoid is not a rare disease in older people Risk of death within two years of diagnosis of bullous pemphigoid is almost three times higher than in matched disease-free people British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Discussion – how does our study compare… Comparison with previous UK estimate (Langan et al, BMJ, 2008) More modest increase in incidence over time (0. 9% vs 17% annual increase) Overall higher incidence rate (7. 6 vs 4. 3/100, 000 person-years) Similar one-year mortality rate (20. 4% vs 19%) Comparison worldwide Incidence rate is similar to Sweden (7. 1/100, 000 person-years) Incidence and prevalence are higher than elsewhere in the world One-year mortality appears marginally better than the rest of Europe (26. 7%), but worse than USA (15. 1%) British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Discussion – strengths and limitations Strengths Limitations Large sample size Use of routinely collected healthcare data at population level Case ascertainment – inaccurate recording or misclassification Validated approach to identifying people with bullous pemphigoid Poor recording of ethnicity (in patients registered with their GP pre-2006) Assumed a person remains a prevalent case until the end of the observation – may overestimate prevalence Accurate recording of death British Journal of Dermatology. DOI: 10. 111/bjd. 19022
Conclusions What does this study add? The incidence of bullous pemphigoid in England was 7. 63 (95%CI 7. 35 to 7. 93)/100, 000 person-years between 1998 -2017 The burden of bullous pemphigoid 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 two years after a diagnosis of bullous pemphigoid compared to people without the disease and remained raised thereafter British Journal of Dermatology. DOI: 10. 111/bjd. 19022
The Team Monica SM Persson Karen E Harman Yana Vinogradova Sinead M Langan Julia Hippisley-Cox British Journal of Dermatology. DOI: 10. 111/bjd. 19022 Kim S Thomas Sonia Gran
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