How common are autoimmune diseases?

We do not know exactly. There is no mechanism in place, in fact, to systematically collect data about the prevalence and incidence of autoimmune diseases (as it exists for infectious diseases and cancers). In addition, since we do not have a complete and universally acceptable list of autoimmune diseases, it is difficult to collect data about something that is not clearly defined.

Scholars have, however, made estimates based of the US prevalence of autoimmune diseases based on published papers and primary data collected from smaller countries that have excellent epidemiological resources (such as the Scandinavian countries). These estimates suggest that all autoimmune diseases combined affect about 3% of the US population, thus approximately 10 million people. To put this estimate into perspective, look at the table below based on the current US population of 329 million.

Disease Prevalence as % of population Prevalence as # of people
Obesity 35% 115 million
All cardiovascular diseases 20% 66 million
Type 2 diabetes mellitus 15% 50 million
All cancers 4% 13 million
All autoimmune diseases 3% 10 million

Collectively, all of the autoimmune diseases weigh heavily upon our public health system. There are many patients with autoimmune diseases that require medical care for decades.

The Most Common Autoimmune Diseases

An estimate of the 10 most common autoimmune diseases in the US is shown in the bar graph below, derived from the paper by Jacobson et al, Clin Immunol Immunopathol, 1997. The graph also shows that autoimmune diseases tend to be more common in females than males. But this is not true across the board; in fact, some autoimmune diseases such as type 1 diabetes mellitus affect the two sexes equally.

10 most common autoimmune diseases graph