In a new study, Mayo Clinic researchers and collaborators have described — for the first time — the prevalence of autoimmune diseases in the U.S. Their research, published in the Journal of Clinical Investigation, reports that about 15 million people are estimated to have one or more of 105 autoimmune diseases. The study also found that autoimmune diseases occur most often in women and identified the top autoimmune diseases by prevalence, sex and age.

"Knowing the number of patients with an autoimmune disease in the U.S. is critical to assess whether these diseases are increasing or decreasing over time and with treatment," says the study's corresponding author, DeLisa Fairweather, Ph.D., vice-chair of translational research for the Department of Cardiovascular Medicine at Mayo Clinic in Florida. "Knowing this number is also critical for funding agencies to raise money and awareness for research into autoimmune diseases as a group and for individual autoimmune diseases like rheumatoid arthritis or multiple sclerosis. Knowing which diseases occur more often in males or females and at what age is critical in understanding the pathogenesis of disease and how they impact the healthcare system."  Dr. Fairweather also leads the Translational Cardiovascular Disease Research Laboratory.

To conduct the study, Dr. Fairweather and co-senior author Aaron Abend from the Autoimmune Registry used electronic health record data from over 10 million patients from six large medical systems in California, Florida, Massachusetts, Iowa, Wisconsin and Missouri who had been diagnosed with at least one of 105 autoimmune diseases considered in the study. They then extended the data to an estimated U.S. population of 333.3 million. The researchers developed a program algorithm to compute the first nationwide prevalence estimate of autoimmune diseases as a category. Dr. Fairweather says previous U.S. estimates were based on meta-analyses and extrapolations for individual autoimmune diseases, which can make estimations of prevalence inaccurate. She says many challenges have existed to obtain accurate prevalence data, including the lack of international consensus on a definition of autoimmune disease.

The findings indicated that about 15 million people, or 4.6% of the U. S. population, were diagnosed with at least one autoimmune disease between January 2011 and January 2022, and that 34% of those individuals were diagnosed with more than one autoimmune disease.

The study also found:

• Females (63% of those with autoimmune disease) were almost twice as likely as males (37%) to be diagnosed with an autoimmune disease.
• 65% of patients had one autoimmune disease.
• 24% of patients had two autoimmune diseases.
• 8% of patients had three autoimmune diseases.
• 2% of patients had four or more autoimmune diseases.

The top five diseases based on prevalence were rheumatoid arthritis, psoriasis, type I diabetes, Graves' disease and autoimmune thyroiditis.

"What dramatically stands out with this assessment is that the most prevalent autoimmune diseases occur in women and autoimmune diseases that occur more often in men occur rarely," says Dr. Fairweather. "This raises important questions that need to be answered with more research. For example, could this be the result of diagnosis bias, or is this a fundamental biological sex difference?"

Dr. Fairweather served on a National Academy of Sciences, Engineering and Medicine (NASEM) committee on autoimmune diseases and testified before Congress in May 2022 to give recommendations for advancing research in autoimmune diseases. This led to the establishment of a new National Institutes of Health (NIH) Office of Autoimmune Disease Research within the Office of Research on Women's Health. In December 2023, the NIH sought input from members of the scientific community, federal partners, academic institutions, the private sector, health professionals, professional societies, advocacy groups, patient communities and other interested people for the development of an NIH-wide strategic plan to advance autoimmune disease research.

Dr. Fairweather says her team has provided the program algorithm freely to the research community, allowing anyone to leverage this research tool to replicate the study using almost any healthcare database. In addition, researchers can use the tool over time to track shifts in the prevalence of autoimmune diseases, offering valuable insights for future research.

This research was partially funded by a National Institutes of Health grant under award R01 HL164520. For a complete list of authors, disclosures and funding, see the paper.

Related Articles