Increasing Prevalence of Antinuclear Antibodies in the United States
Autoimmunity appears to be increasing in the United States, according to a study published in Arthritis and Rheumatology.
Frederick Miller, MD, National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health, Bethesda, Maryland, and colleagues found that the prevalence of antinuclear antibodies (ANA) was significantly increasing in the United States overall and particularly in certain groups. These groups include males, non-Hispanic whites, adults aged 50 years and older, and adolescents.
The study is the first to evaluate ANA changes over time in a representative sampling of the US population.
“The reasons for the increases in ANA are not clear, but they are concerning and may suggest a possible increase in future autoimmune disease,” said Dr. Miller. “These findings could help us understand more about the causes of these immune abnormalities and possibly learn what drives development of autoimmune diseases and how to prevent them.”
The study included 14,211 participants aged 12 years and older in the US National Health and Nutrition Examination Survey (NHANES). The researchers used immunofluorescence to examine the frequencies of ANAs in subjects from 3 time periods. They found that ANA prevalence from 1988 to 1991 was 11.0%, while for 1999 to 2004 it was 11.5%, and for 2011 to 2012 it was 15.9%. These percentages corresponded to 22, 27, and 41 million affected individuals, respectively.
Of the 4 demographic groups that displayed considerable ANA increases, findings in the adolescent group were the most worrisome to the research team. Young people, aged 12 to 19 years, had the largest ANA increases in the study, going from a 2-fold to a 3-fold increase over the 3 time frames.
The researchers 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, research suggests that changes in lifestyle or the environment may be involved in ANA increases.
“These new findings may have important public health implications and will help us design studies to better understand why some people develop autoimmune diseases,” said Christine Parks, PhD, NIEHS.
Determining whether autoimmune diseases, like lupus or myositis, are increasing in prevalence requires a clinical evaluation, which was not performed in the current study. Nevertheless, ANA are commonly seen in patients with these conditions and similar autoimmune disorders. 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 important study will stimulate further research on the environmental factors related to the apparent increased prevalence of autoimmune diseases,” said Dr. Zeldin.
SOURCE: National Institutes of Health