Global age-standardized rates of prevalence for psoriasis, inflammatory bowel disease, rheumatoid arthritis, and multiple sclerosis (MS) were found to be somewhat higher in the US and Europe compared to Africa and Asia, according to new findings.¹

The occurrence of different autoimmune diseases varies across regions and countries due to factors like environmental triggers, genetics, and sociodemographic development.² Prior to this new study, research on autoimmune disease prevalence has been limited to specific regions or countries, relying on data from cohorts or registry systems.

This research was authored by Fan Cao, MD, from the Department of Ophthalmology at the Second Affiliated Hospital of Anhui Medical University in China.

“We here used worldwide data extracted from GBD 2019, to describe current situation (2019) and analyze temporal trends (1990–2019) of prevalence for four autoimmune diseases including rheumatoid arthritis (RA), inflammatory bowel disease (IBD), multiple sclerosis (MS) and psoriasis, at the global, continental, and national levels,” Cao and colleagues wrote.

Background and Findings

The investigators noted that the global prevalence of autoimmune conditions currently stands at an estimated 10% and continues to rise. Despite several notable therapeutic advancements, the associated health and economic burdens on those with such conditions remains substantial.

The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 served the research team as a useful resource for epidemiological research in this study. By assessing data from GBD, it is possible to analyze trends, describe disease burden, and evaluate the current status and changes of diseases in various regions and countries.

The team used GBD 2019 to comprehensively assess the health impact of 369 diseases, impairments, and injuries along with 87 risk factors, examined across 204 countries and territories using the latest available epidemiological data.

From GBD 2019, estimates and 95% uncertainty intervals (UI) for the age-standardized prevalence rate of irritable bowel syndrome, rheumatoid arthritis, MS, and psoriasis were collected by the investigators.

The investigators analyzed the adjusted prevalence rates of these autoimmune conditions in 2019 at the global, continental, and national levels. Temporal trends from 1990 to 2019 were examined using joinpoint regression analysis, by calculating the annual percentage change (APC) and average APC (AAPC), accompanied by their respective 95% confidence intervals (CI).

Overall, the research team reported that in 2019, the average standardized prevalence rate for inflammatory bowel disease, rheumatoid arthritis, MS, and psoriasis globally were as follows:

• 59.25 (95% uncertainty interval [UI]: 52.78 - 66.47)
• 224.25 (95% UI: 204.94 - 245.99)
• 21.25 (95% UI: 18.52 - 23.91)
• 503.62 (95% UI: 486.92 - 519.22)

The team noted that prevalence rates were found to generally have been higher in Europe and America compared to Africa and Asia. From 1990 - 2019, they reported a significant increase in the global rate for rheumatoid arthritis (AAPC = 0.27%, 95% CI: 0.24 to 0.30; P < 0.001).

Conversely, the investigators added that substantial decreases were observed for irritable bowel disease (AAPC = -0.73%, 95% CI: -0.76 to -0.70; P < 0.001), MS (AAPC = -0.22%, 95% CI: -0.25 to -0.18; P < 0.001), and psoriasis (AAPC = -0.93%, 95% CI: -0.95 to -0.91; P < 0.001).

These changes were found to have occurred at different continents and periods, with substantial variations. Across 204 different countries and territories, the trends in prevalence for these 4 diseases was shown to have displayed significant variability.

“There is a strong heterogeneity in prevalence (2019), as well as their temporal trends (1990–2019) of autoimmune diseases across the world…which may be instructive for better understanding the epidemiology of these diseases, appropriately allocating the medical resources, as well as making relevant health policies,” they wrote.

References

1. ^{Cao F, Liu YC, Pan HF, et al. Temporal trends in the prevalence of autoimmune diseases from 1990 to 2019. Autoimmun Rev. 2023;22(8):103359. doi:10.1016/j.autrev.2023.103359.}
2. ^{Cao F, He YS, Wang Y, Zha CK, Lu JM, Tao LM, Jiang ZX, Pan HF. Global burden and cross-country inequalities in autoimmune diseases from 1990 to 2019. Autoimmun Rev. 2023;22(6):103326. doi:10.1016/j.autrev.2023.103326.}