One in 10 people now have an autoimmune disorder, and rates have doubled for coeliac disease, Sjogren's syndrome and Graves’ disease, a UK study finds.
One in 10 people have an autoimmune disease, and rates for some have jumped significantly over the last two decades, according to a UK study.
This proportion is higher than previously thought, the authors wrote in The Lancet.
The database study of more than 22 million individuals found a 22% increase in new diagnoses over the 19-year study.
The largest increases in new diagnoses were seen in coeliac disease, Sjogren’s syndrome and Graves’ disease, which all doubled over the period.
But it wasn’t all bad news. Pernicious anaemia and Hashimoto’s thyroiditis both dropped by around 20%, which the authors suggested could be due to more judicious use of drugs that treat subclinical hypothyroidism in older adults, and better uptake of dietary supplements that prevent anaemia.
While there was a 22% increase in overall new diagnoses of these immune-mediated inflammatory diseases, this was largely driven by secondary diagnoses. First-time diagnoses increased by only 4%.
The prevalence of the 19 conditions included in the analysis rose from 8% to 11% over the study period.
Socioeconomic status appeared to play a role in some conditions, and people in the most disadvantaged quintile were 72% more likely to be diagnosed with pernicious anaemia than the most advantaged group, 52% more likely to be diagnosed with rheumatoid arthritis, 36% more likely to be diagnosed with Graves’ disease and 35% more likely to be diagnosed with systematic lupus erythematosus (SLE).
The authors said this could be the result of environmental factors such as obesity, diet, smoking and pollution.
In contrast, coeliac disease and polymyalgia rheumatica were more commonly found in the most advantaged quintiles. This was “a phenomenon rarely observed in public health research, which could be linked to increased awareness and testing for these diseases in more affluent populations or indeed lifestyle differences”, the authors said.
Women accounted for 64% of all diagnoses, and the average age of diagnosis was 54.
The incidence increased with age for many conditions, such as Graves’ disease, pernicious anaemia and rheumatoid arthritis. Diagnoses of coeliac, inflammatory bowel disease and vasculitis peaked in childhood/early adulthood and then again in later adulthood.
Comorbidity between autoimmune diseases was common, particularly among connective tissue diseases. The rate of incidence of Sjögren’s syndrome was found to be over eight times higher in those with SLE than the general population. This was also seen when looking at co-occurrence of Sjögren’s with systemic sclerosis and systemic sclerosis with SLE.
Meanwhile, a diagnosis of type 1 diabetes in childhood was also linked with higher rates of Addison’s disease (26 times higher), coeliac disease (28 times higher) and thyroid disease (7-13 times higher) throughout life.
“Such observations have been reported before and might suggest overlapping genetic or environmental risk factors, or be due to people with a first autoimmune disease being more likely to undergo screening for these conditions,” the researchers wrote.
People were more likely to be diagnosed with Addison’s disease diagnoses after a diagnosis of almost all other autoimmune disorders, which the authors suggested could be the result of glucocorticoid treatment.
“The observed increase in incidence of rheumatic diseases will probably have important implications for health services and the substantial medication expenditures linked to biologics,” the authors noted.
