One in 10 living with an autoimmune disease in the UK

Roughly one in 10 people in the UK now have an autoimmune disease, a figure much higher than previously thought, according to a new study published in The Lancet.

The findings are based on the research of experts from KU Leuven, UCL, the University of Glasgow, Imperial College London, Cardiff University, the University of Leicester, and the University of Oxford.

The researchers used anonymised electronic health data from 22 million individuals and examined whether incidence of autoimmune diseases is rising over time, who is most affected by these conditions, and how different diseases may co-exist with each other.

Type 1 diabetes is on the rise

An autoimmune disease occurs when the immune system mistakenly attacks normal healthy cells in the body. Although each disease is unique, many share hallmark symptoms, such as fatigue, dizziness, and low-grade fever.

The exact causes of autoimmune diseases remain largely unknown, including how much can be attributed to a genetic predisposition to disease and how much is down to exposure to environmental factors.

There are more than 80 known autoimmune diseases, but the researchers investigated 19 of the most common, including coeliac disease, type 1 diabetes, inflammatory bowel disease and multiple sclerosis.

The rate of some autoimmune diseases (such as type 1 diabetes) has risen in recent years, which has raised questions about what factors may have caused this, such as environmental factors or behavioural changes in society.

Some autoimmune diseases share common risk factors

The researchers found that these 19 autoimmune diseases affect around 10% of the population, much higher than previous estimates which ranged from 3-9%. Women were almost twice as likely to be affected than men (13% compared to 7% respectively).

They also discovered that these conditions are unlikely to be caused by genetic differences alone, and modifiable risk factors – such as smoking, obesity or stress – may increase the likelihood of developing an autoimmune disorder.

In some cases, a person with one autoimmune disorder was also more likely to develop another, according to co-author of the study, Dr Nathalie Conrad.

“We observed that some autoimmune diseases tended to co-occur with one another more commonly than would be expected by chance or increased surveillance alone. This could mean that some autoimmune diseases share common risk factors, such as genetic predispositions or environmental triggers. This was particularly visible among rheumatic diseases and among endocrine diseases.

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“But this phenomenon was not generalised across all autoimmune diseases. Multiple sclerosis, for example, stood out as having low rates of co-occurrence with other autoimmune diseases, suggesting a distinct pathophysiology,” she said.

Disentangling the commonalities and differences

The researchers say there is now a “crucial need” to increase research efforts aimed at understanding the underlying causes of these conditions.

“[This] will support the development of targeted interventions to reduce the contribution of environmental and social risk factors,” says co-author Professor Geraldine Cambridge.