545 - Prevalence of moderate and severe atopic dermatitis in Ireland: a cross-sectional, real-world study of a secondary care population.
Authors: Gough Oisín Shane , McEvoy Fiona , O’Connell Michael , Lynch Maeve , Kirby Brian , Murphy Michelle 
Published: February 2024

Abstract

Introduction/Background
Atopic dermatitis (AD) is a common chronic inflammatory skin disease with significant unmet needs globally.1 European prevalence rates range from up to 8% and 20% of adults and children respectively.2 In the E.U., a 12-month prevalence of AD has been reported at 4.4%.4 Self-reported moderate-to-severe AD affects between 46-66% of E.U. adult AD patients.4 However, global prevalence estimates vary widely. In Ireland, the epidemiology of AD is not fully understood.

Objectives
The aim of this study was to estimate the prevalence of patients aged 12 years or older presenting to secondary care dermatology clinics in Ireland with moderate-to-severe AD. The primary objective was to estimate the prevalence of patients aged 12 years and over with moderate or severe AD within secondary care clinics in Ireland. Secondary objectives included estimating the prevalence and incidence of moderate-to-severe AD patients aged 12–17 and ≥ 18 years respectively within secondary care clinics in Ireland.

Methods
Three secondary care sites located in the south of Ireland collated the number of AD patients ≥ 12 years old (one visit per patient only) with moderate or severe AD presenting between August 2021 and March 2022. The aggregated six-month data from each site was expected to include all patients with AD being actively treated within secondary care in the Munster region. As this epidemiological study was exploratory in nature, no limit was placed on the volume of aggregated patient data collected. Prevalence of AD was standardised to the regional population by dividing the total number of patients with a clinic visit, by the regional population covered by the sites using the 2016 census data. Incidence of AD was standardised similarly by dividing the total number of new patients attending clinic by the regional population covered by the sites using the 2016 census data. The regional prevalence and incidence estimates were stratified by age group and gender and then multiplied by the total Irish population (per the 2016 county level census data) to estimate the national number of cases of moderate and severe AD in secondary care over a six-month period.

Results
The outcome of the analysis estimates an overall prevalence rate for moderate-to-severe AD in secondary care in Ireland of 2.893 patients per 10,000 people in the Irish population. The total estimated number of moderate-to-severe AD cases in secondary care was 1,141. The prevalence rate (95% CI) was 1.456 (1.236, 1.704) and 1.437 (1.218, 1.683) per 10,000 for patients with moderate AD and severe AD respectively. The highest overall prevalence rate of 6.03 patients per 10,000 of the Irish population was observed for patients aged 12–17 years with moderate-to-severe AD in secondary care. Amongst adults, similar prevalence rates were reported for moderate and severe AD patients (1.204 and 1.359 patients per 10,000 respectively) with the highest prevalence rates for 18–24 year olds (2.680 and 2.776 patients per 10,000 for moderate and severe AD respectively). An overall incidence rate of 0.385 patients per 10,000 (in 6-months) was observed for patients aged 12 years and older with moderate-to-severe AD in secondary care, with an estimated 152 new AD patients entering secondary care in Ireland in 6 months. Twenty percent of all current AD patients had attended their first secondary care AD clinic visit during the study period.

Conclusions
Considering E.U. prevalence estimates of AD4, the findings of this study suggest that a very small proportion of patients with moderate-to-severe AD are being seen in secondary care clinics in Ireland.