Autoimmunity incidence on the rise in U.S.

Autoimmunity, a condition in which the body's immune system reacts with components of its own cells, appears to be increasing in the United States, according to new research from the National Institutes of Health published in the journal Arthritis and Rheumatology.

In the study, the researchers found that the prevalence of antinuclear antibodies (ANA), the most common biomarker of autoimmunity, was significantly increasing in the U.S. overall and particularly in certain groups. These groups include males, non-Hispanic whites, adults 50 years and older, and adolescents.

The study included 14,211 participants, 12 years and older, in the U.S. National Health and Nutrition Examination Survey (NHANES). The scientists used immunofluorescence, a technique that uses fluorescent dye to visualize antibodies, to examine the frequencies of ANAs in subjects from three time periods. They found that ANA prevalence for 1988 through 1991 was 11 percent, while for 1999 through 2004 it was 11.5 percent, and for 2011 through 2012 it was 15.9 percent. These percentages corresponded to 22, 27, and 41 million affected individuals, respectively.

Of the four demographic groups that displayed considerable ANA increases, findings in the adolescent group were the most worrisome to the research team. Young people, ages 12-19, had the largest ANA increases in the study, going from a two-fold to a three-fold increase over the three timeframes.

The researchers said they want to know why they are seeing these changes in autoimmunity in each of the groups, but especially in teenagers. Since people have not changed much genetically during the past 30 years, the scientists suggest that changes in lifestyle or the environment may be involved in ANA increases, the researchers said.

Determining whether autoimmune diseases are increasing in prevalence requires a clinical evaluation, which was not performed in this study. Nevertheless, ANA are commonly seen in patients with these conditions and similar autoimmune disorders. Darryl Zeldin, MD, study co-author and NIEHS scientific director, in a statement. He said the researchers hope that a national registry of autoimmune diseases will be established so that they can examine changes over time, define geographic hotspots, and eventually understand what is causing them.

"Hopefully, this… study will stimulate further research on the environmental factors related to the apparent increased prevalence of autoimmune diseases," Zeldin said.