Incidence, prevalence, and life expectancy of patients with generalised pustular psoriasis in England: a population-based cohort study exploring ethnic and sex variations.

BACKGROUND: Generalised pustular psoriasis (GPP) is a rare, severe inflammatory skin disease associated with significant morbidity and increased mortality. Population-based data on the epidemiology of GPP examining ethnic and sex differences, and life-expectancy, remain scarce. OBJECTIVES: To examine the epidemiology of GPP in England over a 15-year period (2008-2022), all-cause and cause-specific mortality risk associated with GPP, and life expectancy including years of life lost associated with age at diagnosis. METHODS: A population-based cohort study using the Clinical Practice Research Datalink linked with hospital, mortality, deprivation, and ethnicity records. Patients with a diagnosis of GPP from primary care or hospital records were identified. Annual prevalence and incidence rates were calculated. Individuals with incident GPP were matched with up to 10 comparators without GPP. Flexible parametric survival models estimated adjusted hazard ratios (aHRs) for the association between GPP and mortality. Abridged life tables were used to estimate years of life lost. RESULTS: Among 25.8 million people, 991 with GPP were identified (63% female; 86% White, 10% Asian, 3% Black/Mixed/Other). GPP prevalence increased from 20.9 per million in 2008 to 32.5 per million in 2022, with higher rates in females, the Asian population, and older age groups. Incidence remained stable until 2016, followed by an upward trend reaching 4.9 per million person-years. Mean age (SD) at onset was 51.4 (21.2) years, occurring earlier in Asian people than in White people. All-cause mortality risk was over three times higher for patients with GPP compared with people without GPP (aHR 3.19; 95% CI 2.58-3.91). Death rates were elevated with GPP for neoplasms, respiratory, digestive, and circulatory diseases, and particularly sepsis (aHR 9.76 [4.92-19.35]). A younger age at diagnosis of GPP was associated with the greatest reduction in life expectancy. CONCLUSIONS: Over the past 15 years, the prevalence of GPP in England increased by more than 50%, with notable differences by sex and ethnicity. GPP was associated with elevated risks of all-cause and cause-specific mortality and reductions in life expectancy. These findings highlight the clinical burden of GPP and the need for appropriate and targeted strategies to reduce preventable morbidity and mortality.