Pustular psoriasis, is a rare form of psoriasis, that is characterised by widespread pustules (white, pus-filled, painful bumps) on a background of red and tender skin. There are different types of pustular psoriasis that depend on where the symptoms appear: Palmoplantar pustulosis (PPP) is when pustules appear on the palms of the hand and/or soles of the feet. Generalised pustular psoriasis (GPP) describes pustules that affect large areas of the body. Patients with GPP often develop symptoms beyond the skin, such as fever, chills and fatigue, which can lead to serious complications, and even death. Due to the rareness of PPP and GPP, literature is limited. The number of individuals in the UK affected by these conditions are unknown. There are also no studies reporting the extent of healthcare utilisation in the UK, and no recent studies investigating the death rates of these patients.
The objective of this study is to address these unknowns by conducting a retrospective analysis of routinely collected primary care data in England (CPRD Aurum). This study will report the following for PPP and GPP patients, compared to patients with the more commonly diagnosed plaque psoriasis/psoriasis vulgaris (PV): number of individuals who develop these conditions (incidence), the number of individuals who are affected at a given timepoint (prevalence), healthcare utilisation, and mortality rates. It is anticipated that this study will further the understanding of the disease landscape of these rare diseases in the UK, in particular highlighting the difference with PV.
Generalised pustular psoriasis (GPP) and palmoplantar pustulosis (PPP) are two sub-classifications of pustular psoriasis. GPP is characterised by rapidly progressing diffuse erythematous patches with pustules that coalesce to form lakes of pus. Patients with GPP may experience flares which can lead to serious complications such as sepsis, and even death. In PPP, pustules are restricted to the palms of hands and soles of feet. Both GPP and PPP can occur independently of a history of psoriasis.
This retrospective descriptive cohort study will utilise primary electronic health records linked to Hospital Episodes Statistics (HES) and Office of National Statistics (ONS) datasets to quantify prevalence, incidence, mortality, and resource utilisation of GPP and PPP compared to the more commonly diagnosed psoriasis vulgaris (PV).
The primary objectives of this study include the estimation of prevalence, incidence, and patient characteristics of GPP, PPP, and PV between 1st January 2008 and 31st December 2019. The secondary objectives will estimate the all-cause mortality for each cohort using Kaplan-Maier analysis during this time period and recent healthcare resource utilisation (HCRU) during 1st January 2015 to 31st December 2019.
Patient characteristics and HCRU will be stratified by prevalent and incident cases and by patient cohort. categorical variables will be tabulated with frequencies and percentages whereas the mean/standard deviation or will be used to describe continuous variables. Prevalence, incidence, and mortality will be directly standardised by age and sex from 01st January 2008 to 31st December 2019. These rates will also be presented using negative binomial Poisson regression adjusted for age and sex.
The study design has been chosen as it is appropriate for data extracted from healthcare datasets that already have data collected retrospectively. CPRD-HES linked dataset has been chosen due to the availability of good quality data for procedures, demographics, costs, complications, readmissions and resource use.
Health Outcomes to be Measured:
Prevalent cases and rate of GPP,PPP, and PV; Incident cases and rate of GPP,PPP, and PV
Number of prior hospitalisations; Mortality rate (By 5-year age group and sex; directly standardised to 2019 1st July CPRD general population); healthcare utilisation: number/NHS cost of A&E visits, outpatient visits, inpatient admissions, and general practitioner (GP) visits
Number and cost of psoriasis prescriptions/treatments
Psoriasis Area Severity Index (PASI) scores
Incidence, prevalence, and mortality of GPP,PPP, and PV patients will be stratified by 5-year age groups and sex; directly standardised to 2019 1st July CPRD general population):
HES Accident and Emergency;HES Admitted Patient Care;HES Outpatient;ONS Death Registration Data;Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation