Epidemiology and management of atopic dermatitis in England: an observational cohort study protocol

Introduction Atopic dermatitis (AD) is one of the most common inflammatory skin conditions in both children and adults. Despite this, contemporary descriptions of the incidence, prevalence and current management of the condition in the UK are lacking. Methods and analysis We will perform a series of retrospective studies using a large population-based cohort derived from the Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) network database to explore two key research themes: AD epidemiology and AD management. In the epidemiology theme, we will describe the incidence and prevalence of AD in children and adults in England from 2009 to 2018 inclusive. We will stratify findings by age, national Index of Multiple Deprivation (IMD), ethnicity, urban-rural environment and geographic location; and explore independent associations of these features with AD in multivariable models. In the management theme, we will explore healthcare utilisation and treatment in people with AD. Regarding healthcare utilisation, we will evaluate rates of AD-associated primary care visits and specialist dermatology referrals in people with AD. Rates will be stratified by age, gender, socioeconomic IMD quintile and ethnicity. We will describe contemporary treatment by estimating prescribing rates across medication classes used in AD (emollients, topical corticosteroids by potency, topical calcineurin inhibitors, topical antimicrobials, antihistamines, oral corticosteroids and systemic immunomodulatory therapies) overall, and by age and sociodemographic groupings. We will also examine trends in prescribing over the study period. In people first diagnosed with AD during the study period, we will describe differences in treatment escalation by sociodemographic factors using time-to-event analysis. Ethics and dissemination The Health Research Authority decision tool classed this a study of 'usual practice', ethics approval was not required. Study approval was granted by the RCGP RSC Study Approval Committee. Results will be disseminated through peer-reviewed publications.