Atopic dermatitis epidemiological research methodology: a global scoping review.

Background: Atopic dermatitis has the highest burden of all skin diseases globally. While numerous systematic reviews and meta-analyses have attempted to estimate the burden of atopic dermatitis at country, regional, and global levels, the variability in research methodology often leads to the exclusion of significant portions of data or the aggregation of data representing disparate factors. As a result, improving the understanding of the burden of atopic dermatitis requires a thorough review of the methodologies currently in use.

Objective: This scoping review aims to identify and map the research methodology used in population-based epidemiological studies of atopic dermatitis in terms of the case definitions used, the severity assessment method, measures of frequency and key socio-demographic factors.

Methods: A systematic literature search was conducted covering an 18-month period from 1st January 2023 to 31st July 2024. Original, population-based studies were included if they reported the prevalence and/or incidence of atopic dermatitis. Abstract screening and data extraction was done in duplicate and blinded. Descriptive analyses stratified by geographic region and age group are presented in tabular and graphical form.

Results: A total of 111 studies were included across 48 countries. Data on atopic dermatitis prevalence used various diagnostic criteria, with studies defining cases by a physician diagnosis (69%), validated questionnaires (13%), and other methods (19%) with considerable heterogeneity between geographic regions. Nineteen studies (17%) reported the severity distribution. Geographical regions with the fewest studies on atopic dermatitis were the South-East Asian (4%) and African (3%) regions.

Conclusion: Recent population-based epidemiological studies on atopic dermatitis are highly heterogeneous, limiting meaningful comparisons across studies. Future research should aim to address this variability and fill key geographical gaps in the global burden data.