Introduction & Objectives
Autoimmune diseases are characterized by damaging immune responses to self-antigens and, for the most part, are of unknown etiology. They are thought to affect 3–5% of the population, with increasing rates observed several decades ago. Recent studies suggest continued increases in the rates of certain autoimmune diseases, but whether these trends are due to changes in recognition and diagnosis, or if they are true temporal changes in incidence remains unclear.
Dinse et al. set out to investigate whether the prevalence of anti-nuclear antibodies (ANAs), the most common biomarker of autoimmunity, changed over a recent 25-year span in the U.S.
Methods
Serum ANA levels were measured by standard indirect immunofluorescence assays on HEp-2 cells in 14,211 participants age 12 years and older in the National Health and Nutrition Examination Survey, with approximately one-third from each of three time periods: 1988–91, 1999–2004, and 2011–12. The researchers used logistic regression adjusted for sex, age, race/ethnicity and survey design variables to estimate changes in ANA prevalence across the time periods.
Results & Discussion
There was strong evidence that ANA prevalence increased over time, primarily from the second time period to the third time period.
The prevalence of ANAs was 11.0% (95% confidence interval [95% CI] 9.7–12.6%) in 1988–1991, 11.5% (95% CI 10.3–12.8%) in 1999–2004, and 15.9% (95% CI 14.3–17.6%) in 2011–2012 (P for trend < 0.0001), which corresponds to ~22 million, ~27 million and ~41 million affected individuals, respectively.
Among adolescents aged 12–19 years, ANA prevalence increased significantly, with odds ratios (ORs) of 2.02 (95% CI 1.16–3.53) and 2.88 (95% CI 1.64–5.04) in the second and third time periods relative to the first (P for trend < 0.0001).
ANA prevalence increased in both sexes (especially in men), older adults (age ≥50 years) and non-Hispanic whites.
These increases in ANA prevalence were not explained by concurrent trends in weight (obesity/overweight), smoking history or alcohol consumption.
Conclusion
The prevalence of ANA in the U.S. has increased considerably in recent years. Additional studies to determine factors underlying these increases in ANA prevalence could elucidate causes of autoimmunity and enable the development of preventive measures.
Refer to the full study for all source material.
Excerpted and adapted from:
Dinse GE, Parks CG, Weinberg CR, et al. Increasing prevalence of antinuclear antibodies in the US. Arthritis Rheumatol. 2020 Jun;72(6):1026–1035.
