By David Douglas
NEW YORK (Reuters Health) Feb 07 - Roughly one in seven U.S. adults has antinuclear antibodies (ANA), researchers report.
"These findings emphasize how common ANA positive tests are in the general population and who is most likely to have them," senior author Dr. Frederick W. Miller told Reuters Health by email.
Dr. Miller, of the National Institutes of Health in Bethesda, Maryland and colleagues note that ANA prevalence estimates have ranged from as little as 1.1% to as high as 20%. They note that estimates often come from selected populations, or are developed using different methods. Some reports suggest a higher prevalence in women and the elderly, but firm data are lacking.
For a study published online January 5th in Arthritis & Rheumatism, the researchers analyzed serum samples from 4,754 participants in the US National Health and Nutrition Examination Survey (NHANES) from 1999-2004.
The overall ANA prevalence in adolescents and adults together (everyone at least 12 years old) was 13.8%. The prevalence was significantly higher in women than men (17.8% vs 9.6%); the disparity peaked in the fifth decade.
The adjusted prevalence odds ratio was slightly greater in blacks than whites (1.30). It was lower in people who were overweight or obese compared to those of normal weight (0.74). Broadly, the prevalence increased with age.
Although some individuals had more than one ANA staining pattern, the most common patterns were nuclear (84.6%). Cytoplasmic patterns were seen in 21.8% and nucleolar patterns in 6.1%.
The most common specific autoantibodies were anti-Ro autoantibodies (3.9%), followed by anti-Su autoantibodies (2.4%).
These findings show "a high prevalence of ANA in the U.S., especially in females and older individuals," the authors say. They estimate that 32 million people are affected, and they say the number is likely to increase.
Dr. Miller stressed, however, that "there are many possible causes for a positive ANA, and these causes should be considered when ordering and interpreting ANA tests in individual patients."
SOURCE: http://bit.ly/yXXc8J
Arthritis Rheum 2012.
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