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18th February 2023
Having autoimmune diseases (AIDs) seems to increase the risk of developing atrial fibrillation according to the findings of a prospective study by Dutch researchers.
Atrial fibrillation (AF) is the most common cardiac arrhythmia and data from 2017 suggests that globally, there were 3.046 million new cases. Although the underlying cause of AF remains uncertain, there is a suggestion of a mechanistic link with inflammatory processes. Moreover, a feature of autoimmune diseases such as rheumatoid arthritis is inflammation and one meta-analysis found a 29% higher risk of AF among those with rheumatoid arthritis. Nevertheless, the link between AF and other autoimmune disorders is less clear. As a result, in the current study, the Dutch team turned to data held in the UK Biobank and looked for those diagnosed rheumatic fever, gastrointestinal AIDs and other AIDs e.g. those affecting the musculoskeletal, connective tissues and neurological systems. Such individuals were monitored over time for the development of AF. In addition, the team collected data on cardiovascular risk factors such as hypertension, type 2 diabetes, body mass index etc and which were adjusted for in regression models.
Autoimmune diseases and development of atrial fibrillation
A total of 494,072 individuals with a median age of 58 (54.8% female) were followed for a median of 12.8 years and during this time 5.5% of the cohort developed AF.
In fully adjusted models, among those with rheumatic fever but no cardiac involvement, there was a 47% higher risk of developing AF (hazard ratio, HR = 1.47, 95% CI 1.26 – 1.72). Similarly, there were elevated risks for those with several autoimmune diseases including Crohn’s disease (HR = 1.23), ulcerative colitis (HR = 1.17), rheumatoid arthritis (HR = 1.39) systemic lupus erythematosus (HR = 1.82) and systemic sclerosis (HR = 2.32).
When analysed by gender, the researchers found that for many of these disorders, there was a higher risk among women although the risk was higher among men but only for ulcerative colitis.
The authors concluded that whilst their data showed how autoimmune diseases were associated with the development of AF, further evidence was need to support the clinical translation of these findings.
Tilly MJ et al. Autoimmune diseases and new-onset atrial fibrillation: a UK Biobank study. Eurospace 2022 (Online ahead of print)
2nd February 2022
Vitamin D and omega-3 fatty acids taken by adults over a 5-year period led to a 22% reduction in the incidence of autoimmune disease compared to placebo. This was the conclusion of a randomised trial by researchers from the Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, USA.
An autoimmune disease develops due to an immune-mediated attack on the body’s own organs although the underlying pathology for most conditions remains uncertain. Moreover, an estimated 4% of the global population is affected by one of the 80 different autoimmune disease which include conditions such as type 1 diabetes, rheumatoid arthritis, lupus, Crohn’s disease and scleroderma. Although epidemiological evidence indicates a potential preventative role for vitamin D in autoimmune diseases, prospective data are lacking. In addition, a Danish cohort study found that each additional 30g intake of fatty fish containing omega-3 oils was associated with 49% reduction in the risk of rheumatoid arthritis.
However, little is known about the potential synergistic effect of vitamin D and omega-3 fatty acids on the development of an autoimmune disease and this was the purpose of the present study by the US team. They undertook a randomised, placebo-controlled trial, VITAL, which was designed to investigate whether taking daily supplements of vitamin D3 (2000 IU) or omega-3 fatty acids reduced the risk of developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. However, for the present analysis, the team focused on the development of the autoimmune diseases such as rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease and psoriasis. For the trial, participants were randomised to vitamin D or matching placebo and omega-3 fatty acids or matched placebo and self-reported all incidence autoimmune diseases which were confirmed by a review of their medical records. The primary outcome of interest was the incidence of all autoimmune diseases.
Vitamin D and omega-3 fatty acids and autoimmune diseases
A total of 25,871 individuals with a mean age of 67.1 years (50.6% female) were enrolled and followed for a median of 5.3 years. In the vitamin D arm, 123 individuals and 155 in the placebo group had a confirmed autoimmune disease (hazard ratio, HR = 0.78, 95% CI 0.61 – 0.99, p = 0.05). In the separate omega-3 fatty acids arm, 130 compared with 148 in the placebo group developed an autoimmune disease although this difference was non-significant (HR = 0.85, 95% CI 0.67 – 1.08, p = 0.19).
Using a Cox model adjusted for age, sex and race, the authors found that among those randomised to both vitamin D and omega-3, the incidence of confirmed autoimmune disease was lower (HR = 0.69, 95% CI 0.49 – 0.96) compared with placebo.
They concluded that vitamin D supplements with or without omega-3 fatty acids reduced the development of autoimmune diseases.
Hahn J et al. Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial BMJ 2022