Objective: The prevalence of some autoantibodies in the elderly population has been reported to be greater than in younger controls. The prevalence of ANCA has been shown to be low in a generally healthy population, but has not been established in the elderly. Thus, the presence of ANCA in elderly patients might not have the same clinical significance as in younger people. The aim of this study was to evaluate the prevalence of ANCA in elderly subjects.
Patients and methods: Serum samples from 137 subjects (96 females, 41 males; mean age = 82.2 years +/- 6.97 SD) were evaluated. Criteria for exclusion included suspected or established systemic vasculitis, connective tissue or neoplastic diseases, acute infection, HIV infection, current therapy with corticosteroids or cytotoxic drugs, and recent blood transfusion. ANCA were detected by indirect immunofluorescence on ethanol-fixed normal human neutrophils. Fluorescence patterns were classified as c-ANCA, p-ANCA or nuclear. Sera exhibiting p-ANCA or nuclear fluorescence were further tested by IIF on formalin-acetone fixed normal human neutrophils. Sera whose reaction pattern was cytoplasmic were considered as positive for "true" pANCA. Additionally, sera were tested for the presence of antinuclear antibodies (IIF), anti-double-stranded DNA (enzyme immunoassay) and IgM rheumatoid factors (enzyme immunoassay).
Results: The prevalence of c-ANCA was 0% (95% CI = 0-2.66), the prevalence of p-ANCA was 2.2% (95% CI = 0.45-6.3), and the prevalence of "true" p-ANCA was 0.73% (95% CI = 0.02-4). The prevalence of ANA, anti ds-DNA and RF were respectively 38%, 3.6%, and 11.7%.
Conclusion: The prevalence of ANCA is not increased in elderly people. Thus, the presence of ANCA in elderly subjects may have the same clinical significance as in younger people.