Diagnostic value for rheumatoid arthritis of antiperinuclear factor at the 1:100 threshold. Study of 600 patients and meta-analysis of the literature.

Six hundred sera from patients with chronic rheumatic diseases including 429 with rheumatoid arthritis were tested in a blind fashion for IgG antiperinuclear factor using an indirect fluorescent antibody assay on buccal cells. Using the dilution of 1:100 found to be optimal in an earlier study, 283 of the 429 (66%) rheumatoid arthritis sera and 22 of the 171 (13%) control sera were positive for antiperinuclear factor. Titers were higher in the rheumatoid arthritis group than in the control group. A meta-analysis of studies that used sera diluted 1:80 or 1:100 (2853 sera including 939 from patients with rheumatoid arthritis, 1539 from patients with other rheumatic diseases and 375 from healthy controls or patients with unclassified rheumatic diseases) yielded a sensitivity of 0.75, a specificity of 0.93, and a positive predictive value of 0.87. These data demonstrate that antiperinuclear factor testing contributes usefully to the diagnosis of rheumatoid arthritis.