Global burden due to modifiable risks factors for autoimmune diseases, 1990-2021: Temporal trends and socio-demographic inequalities

Background: Autoimmune diseases arise from a combination of non-modifiable risk factors, such as gender and genetic predispositions, and modifiable factors, including lifestyle choices and environmental exposures. Given the potential to alter modifiable risk factors, this study aims to evaluate the global burden, temporal trends, and inequalities of autoimmune diseases attributed to modifiable risk factors from 1990 to 2021. The study will provide up-to-date evidence to inform strategies for mitigating the impact of these risk factors on autoimmune diseases worldwide.

Methods: Data on the global burden of autoimmune diseases attributed to modifiable risk factors were obtained from the Global Burden of Diseases study 2021. Temporal trends in age standardized disability-adjusted life-years (DALYs) rates were evaluated by estimated annual percentage changes (EAPC). Spearman rank correlation test was used to explore the association between two variables. Slope index of inequality (SII) and concentration index (CI) were used to evaluated the absolute and relative inequalities in DALY rates and numbers, respectively.

Results: From 1990 to 2021, type 1 diabetes mellitus (T1DM) due to high temperature has shown an increasing trend in global age standardized DALY rates (EAPC = 0.88, 0.58 to 1.18), whereas all other autoimmune diseases due to specific risk factors have generally exhibited decreasing trends. Across Socio-demographic Index (SDI) quintiles, notable increases were observed in high SDI countries for T1DM due to high temperature (EAPC = 1.36, 0.92 to 1.80), in low and low-middle SDI countries for multiple sclerosis (MS) due to smoking (EAPC = 0.25, 0.23 to 0.27; 0.22, 0.21 to 0.23, respectively), and in low-middle SDI countries for asthma due to high body-mass index (BMI) (EAPC = 0.25, 0.20 to 0.29). In 2021, significant positive associations were observed between SDI and age-standardized DALY rates for rheumatoid arthritis (RA) and MS due to smoking, as well as T1DM due to low temperatures across 204 countries and territories (all P < 0.05). In contrast, all other autoimmune diseases attributed to certain risk factors exhibited significant negative associations (all P < 0.05). Women displayed higher global age-standardized DALY rates for asthma due to high BMI (44.1 per 100,000 population), while men exhibited higher global age-standardized DALY rates for all other autoimmune diseases due to specific risk factors. Except for narrowed inequalities in DALY rates for asthma due to smoking (SII = 20.4, 13.0 to 27.8 in 1990 to 6.7, 2.8 to 10.6 in 2021) and in DALY numbers for asthma due to high BMI (CI = 17.3, 24.5 to 9.5 in 1990 to -0.3, 8.2 to -8.6 in 2021), both absolute and relative SDI-related inequalities have remained stable for all other autoimmune diseases linked to specific risk factors.

Conclusions: Over the past three decades, substantial progress has been achieved in reducing global age-standardized DALY rates for autoimmune diseases attributed to modifiable risk factors, except for T1DM attributed to high temperatures. Despite these advancements, SDI-related inequalities have remained stable for most of these diseases attributed to risk factors, underscoring the urgent need for targeted public health strategies to address these persistent disparities.