Autoimmune disorders arise when the immune system’s typical function of safeguarding the body against infections is disrupted, leading it to erroneously target healthy cells within the body. Conditions such as rheumatoid arthritis, lupus, type 1 diabetes, and multiple sclerosis are among the numerous examples of such disorders.
Over the past few decades, there has been a reported increase in certain autoimmune disorders, including type 1 diabetes. This raises the question of whether the overall incidence of autoimmune disorders is rising. It is possible that common environmental factors or changes in behavior may be contributing to this trend. However, the exact causes of autoimmune diseases, and the extent to which genetics and environmental factors play a role, still largely elude us and require extensive research. One of the main challenges in studying autoimmune diseases is the rarity of individual cases and the multitude of different types, making it difficult to conduct large-scale studies and obtain reliable estimates in order to address these questions.
A collaborative team comprising specialists in epidemiology, biostatistics, rheumatology, endocrinology, and immunology from several esteemed institutions, including KU Leuven, University College London, the University of Glasgow, Imperial College London, Cardiff University, the University of Leicester, and the University of Oxford, have united to address some of these inquiries.
The research utilized an extensive dataset of de-identified electronic health records from the United Kingdom, which encompassed information from 22 million individuals. Its primary focus was to analyze 19 prevalent autoimmune diseases, aiming to determine if their incidence is increasing over time, identify the demographic groups most susceptible to these conditions, and explore potential coexistence between different autoimmune diseases.
The collective impact of these 19 autoimmune diseases on the population amounts to approximately 10%, with women being affected at a higher rate of 13% compared to men at 7%. These findings surpass previous estimates, which were typically based on smaller sample sizes and encompassed fewer autoimmune conditions, ranging from 3% to 9%.
The researchers also discovered discrepancies in socioeconomic status, seasonal patterns, and regional distribution among various autoimmune conditions. They propose that genetics alone cannot fully explain these variations, indicating the potential influence of alterable risk factors like smoking, obesity, or stress in developing certain autoimmune diseases.
The researchers’ findings additionally validate the notion that individuals with an existing autoimmune disease are at a higher risk of developing a second one when compared to those without any autoimmune conditions. These discoveries shed light on new patterns that will likely guide future research in understanding potential shared triggers for various manifestations of autoimmune diseases.
The study found a higher incidence of certain autoimmune diseases occurring together, indicating a potential connection in terms of shared risk factors like genetics or environmental triggers. This pattern was particularly evident among rheumatic and endocrine diseases. However, not all autoimmune diseases followed this trend, as multiple sclerosis, for instance, showed minimal co-occurrence with other autoimmune conditions, suggesting a unique underlying mechanism of development.
Autoimmune diseases affect about one in ten people, and the burden of these illnesses is growing over time. The differences observed among autoimmune disorders show that environmental factors play a role in their pathogenesis. These connections between different diseases suggest that there are shared causes for why they develop – particularly among connective tissue problems and endocrine issues.
- Conrad N, Misra S, Verbakel JY, Verbeke G, Molenberghs G, Taylor PN, Mason J, Sattar N, McMurray JJV, McInnes IB, Khunti K, Cambridge G. Incidence, prevalence, and co-occurrence of autoimmune disorders over time and by age, sex, and socioeconomic status: a population-based cohort study of 22 million individuals in the UK. Lancet. 2023 Jun 3;401(10391):1878-1890. doi: 10.1016/S0140-6736(23)00457-9. Epub 2023 May 5. PMID: 37156255.