Caution regarding historical estimates and trends for global burden of AD

Summary: Abstract Body: The Global Burden of Disease (GBD) Study is a respected source for standardized estimates of the burden of hundreds of diseases that is frequently used to track disease burden trends over time and inform health policy planning. To address discrepancies in recent publications on trends in the global prevalence of atopic dermatitis (AD) using GBD data, we compared estimates of the global prevalence of AD over the same historical period (1990-2017), using data from the three most recent data releases: GBD2017, GBD2019, and GBD2021. We found marked differences by data release year: Data from both GBD2019 and GBD2021 suggest that AD prevalence decreased since 1990, in contrast to GBD2017, which shows an increasing trend. Overall, AD prevalence estimates across the same three decades are highest using data from GBD2017 (2,746 to 2,787 cases per 100,000 people) and lowest using data from GBD2021 (1,673 to 2,015 cases per 100,000 people). To examine the external validity of each data release, we compared historical estimates to age- and year-matched International Study of Asthma and Allergies in Childhood Phase Three data and found low concordance (Pearson correlation coefficient [PCC] -0.133 for GBD 2021 and -0.130 for GBD 2019). Correlations were lowest for low income and non-European countries. The GBD’s modeling tool is designed to incorporate new data. However, it appears that changes in historical GBD estimates are primarily driven by the addition of large insurance claims databases since 2019. Insurance claims databases have limitations for the capture of AD activity and severity and may have limited generalizability, therefore it is important for researchers using GBD data to understand how the employed data sources have changed over time and interpret it with caution. Sheng-Pei Wang^{1, 2}, Elisha M. Myers⁷, Bernd Arents³, Alan Irvine⁴, Sinead Langan⁵, Carsten Flohr⁶, Katrina Abuabara¹ 1. University of California San Francisco, SF, CA, United States. 2. Children's Hospital Los Angeles, LA, CA, United States. 3. Dutch Association for People with AD, Nijkerk, Netherlands. 4. Children's Health Ireland at Crumlin, Dublin, Ireland. 5. Faculty of Epidemiology and Population Health, LSHTM, London, United Kingdom. 6. Global Atopic Dermatitis Atlas, London, United Kingdom. 7. Florida Atlantic University, Boca Raton, FL, United States. Clinical Research: Epidemiology and Observational Research