A global assessment of incidence trends of autoimmune diseases from 1990 to 2019 and predicted changes to 2040

To analyze the global incidence trends for four autoimmune diseases (ADs) including rheumatoid arthritis (RA), inflammatory bowel disease (IBD), multiple sclerosis (MS) and psoriasis from 1990 to 2019, and further predict their changes to 2040 at global, regional, and national levels.The estimates and 95% uncertainty intervals (UIs) for case number and agestandardized incidence rate (ASIR) of RA, IBD, MS and psoriasis were derived from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019. Estimated annual percentage change (EAPC) was utilized to quantify the global incidence trends for RA, IBD, MS and psoriasis from 1990 to 2019. Furthermore, a log-linear age-period-cohort model was adopted to predict the new case number and incidence rates for these four ADs through 2040.From 1990 to 2019, the global ASIR rose significantly for RA (EAPC = 0.30%, 95% CI: 0.26 to 0.34) whereas declined significantly for IBD (EAPC = -0.60%, 95% CI: -0.72 to - 0.48), MS (EAPC = -0.19%, 95% CI: -0.24 to -0.13) and psoriasis (EAPC = -0.77%, 95% CI: -0.78 to -0.76). From 2020 to 2040, the global ASIR of RA, IBD, and psoriasis was predicted to decrease whereas the global ASIR of MS was predicted to increase, with continuous increasing case number of all these diseases. Furthermore, the predicted incidence trends of these four ADs varied significantly across 195 countries and territories, with a prominent higher burden in high-income North America and Western Europe.There are strong heterogeneities in the global incidence trends (1990-2019) and predicted changes (2020-2040) of ADs across the world, highlighting prominent challenges in the control of ADs, including both growing case number and distributive disparities of these diseases worldwide, which may be instructive for better public health policy establishment and healthcare resource allocation.