Age-standardized incidence, prevalence, and mortality rates of autoimmune diseases in adolescents and young adults (15–39 years): an analysis based on the global burden of disease study 2021
Authors: Zhao Meng , Zhai Hongrui , Li Han , Wei Feiran , Ma Hongfei , Liu Yangyang , Li Wei , Wei Pingmin 
Published: July 2024

Abstract
Background
Autoimmune diseases (ADs) present significant health challenges globally, especially among adolescents and young adults (AYAs) due to their unique developmental stages. Comprehensive analyses of their burden are limited. This study leverages the Global Burden of Disease (GBD) 2021 data to assess the global, regional, and national burden and trends of major ADs among AYAs from 1990 to 2021.

Methods
Utilizing data from the Global Burden of Disease (GBD) Study 2021 for individuals aged 15–39 years, we employed a direct method for age standardization to calculate estimates along with 95% uncertainty intervals (UIs) for assessing the age-standardized incidence rates (ASIR), prevalence rates (ASPR), and mortality rates (ASMR) of ADs. The diseases analyzed included rheumatoid arthritis (RA), inflammatory bowel disease (IBD), multiple sclerosis (MS), type 1 diabetes mellitus (T1DM), Asthma, and Psoriasis. Trends from 1990 to 2021 were analyzed using Joinpoint regression, providing average annual percentage changes (AAPC) and 95% confidence intervals (CIs).

Result
In 2021, the global ASIR, ASPR, and ASMR of RA among AYAs (per 100,000 population) were 9.46 (95% UI: 5.92 to 13.54), 104.35 (77.44 to 137.84), and 0.016 (0.013 to 0.019), respectively. For IBD, the corresponding rates were 4.08 (3.07 to 5.37), 29.55 (23.00 to 37.83), and 0.10 (0.07 to 0.12). MS exhibited rates of 1.40 (0.93 to 1.93), 16.05 (12.73 to 19.75), and 0.05 (0.04 to 0.05), respectively. T1DM had rates of 6.63 (3.08 to 11.84), 245.51 (194.21 to 307.56), and 0.54 (0.47 to 0.60). Asthma demonstrated rates of 232.22 (132.11 to 361.24), 2245.51 (1671.05 to 2917.57), and 0.89 (0.77 to 1.08). Psoriasis showed rates of 55.08 (48.53 to 61.93) and 426.16 (394.12 to 460.18) for ASIR and ASPR, respectively. From 1990 to 2021, the global ASIR of RA (AAPC = 0.47, 95% CI: 0.46 to 0.49), IBD (0.22 [0.12 to 0.33]), MS (0.22 [0.19 to 0.26]), T1DM (0.83 [0.80 to 0.86]), and Psoriasis (0.33 [0.31 to 0.34]) showed increasing trends, whereas Asthma (-0.96 [-1.03 to -0.88]) showed a decreasing trend. The global ASPR of RA (0.70 [0.68 to 0.73]), MS (0.35 [0.32 to 0.37]), T1DM (0.68 [0.66 to 0.69]), and Psoriasis (0.29 [0.27 to 0.32]) also showed increasing trends, whereas IBD (-0.20 [-0.27 to -0.13]) and Asthma (-1.25 [-1.31 to -1.19]) showed decreasing trends. Notably, the estimated global ASMR of RA (-2.35 [-2.57 to -2.12]), MS (-0.63 [-0.86 to -0.41]), T1DM (-0.35 [-0.56 to -0.14]), and Asthma (-1.35 [-1.44 to -1.26]) in AYAs declined. Additionally, the burden of disease for ADs in AYAs varies considerably across continents and between 204 countries and territories.

Conclusion
ADs among AYAs present a substantial public health burden with notable regional disparities in incidence, prevalence, and mortality rates. Understanding these patterns is essential for developing targeted public health interventions and policies to mitigate the impact of ADs in this population.