Prevalence of Atopic Dermatitis: A Systematic Review and Meta-Analysis.

Background: Atopic dermatitis (AD) negatively affects quality of life and places a substantial financial burden on health care systems due to treatment costs and increased demand for services. Objective: To estimate the worldwide prevalence of AD, the proportion of severe cases worldwide and explore sources of heterogeneity. Methods: We searched MEDLINE, Embase, and Global Index Medicus from January 2012 up until August 30, 2022. We included primary prevalence studies published from 2012 onward. Study selection was conducted by two reviewers independently. One reviewer performed data extraction and assessed risk of bias using the JBI Critical Appraisal Checklist for Prevalence Studies, with independent checking by a second reviewer. Random-effects meta-analyses were conducted to pool results; subgroup analyses were conducted to evaluate potential modifiers. Certainty of evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation approach. Main outcomes were point prevalence and proportion of severe cases. Results: We identified 12,774 unique references and assessed 1029 full texts, ultimately resulting in the inclusion of 310 studies with 25.5 million individuals. Point prevalence was 11.1% (95% CI 9.4-13.1; 123 studies; 12,776,910 individuals; moderate certainty of evidence) in children and adolescents, and 6.3% (95% CI 5.0-7.8; 59 studies; 12,794,260 individuals; moderate certainty of evidence) in adults. Relatively similar results were observed for studies with low risk of bias. Proportion of severe cases varied from 1.9 to 7.2% in children and adolescents and 2.8% to 15.6% in adults. Conclusions: These findings may underpin effective health care policies, research initiatives, and clinical decision-making.