Prevalence, incidence, mortality, and healthcare resource use for generalised pustular psoriasis, palmoplantar pustulosis, and plaque psoriasis in England: a population-based cohort study.

BACKGROUND:Generalised pustular psoriasis (GPP) and palmoplantar pustulosis (PPP) are chronic, inflammatory skin conditions. Accumulating evidence shows that GPP and PPP have different characteristics compared with plaque psoriasis and are distinct clinical entities. OBJECTIVES:To assess the epidemiology, comorbidities, mortality and healthcare use for patients with GPP and PPP compared with those with plaque psoriasis in England. METHODS:A cohort study involving analyses of longitudinal electronic health record data in the Clinical Practice Research Datalink Aurum database and linked hospital and mortality data between 2008 and 2019. The primary study outcome was the incidence and prevalence rates for GPP, PPP and plaque psoriasis in England. Secondary outcomes included survival rates and healthcare resource use (HCRU) by disease type. RESULTS:We identified 373 patients with GPP, 1,828 with PPP and 224,223 with plaque psoriasis. The mean age was 55.9 years (standard deviation [SD]: 18.6) for patients with GPP, 51.5 years (SD: 16.4) for those with PPP, and 48.5 years (SD: 19.1) for those with plaque psoriasis; 62.5% and 65.9% of patients with GPP and PPP, respectively, were women, compared with 49.4% of those with plaque psoriasis. About half of the patients were overweight or obese at baseline (GPP, 48.6%; PPP, 56.0%; and plaque psoriasis, 45.9%). The incidence rates for GPP, PPP and plaque psoriasis were 0.25 (95% CI: 0.21-0.28), 2.01 (95% CI: 1.92-2.11) and 103.2 (95% CI: 102.5-103.9) per 100,000 person-years, respectively. From 2008 to 2019, the prevalence rates per 100,000 persons ranged from 1.61 to 3.0 for GPP, 1.1 to 18.7 for PPP and 1771.0 to 1903.8 for plaque psoriasis. Survival rates were lower for patients with GPP, particularly those who were over 55 years old and those with a history of ≥1 comorbidity in each cohort. HCRU was lower in the plaque psoriasis cohort and highest in the GPP cohort, particularly among those who had ≥1 GPP flare. CONCLUSIONS:Our results provide further evidence that GPP is a distinct disease with different epidemiology, lower survival and higher HCRU than plaque psoriasis in England.