Characteristics of subjects who received autoantibody testing.
| Characteristic | Autoantibody | ||
|---|---|---|---|
| RF | ANA | CCP | |
| No. subjects tested | 6783 | 7852 | 299 |
| No. positive (%) | 703 (10.4) | 1877 (23.9) | 44 (14.7) |
| Female, n (%) | 4706 (69.4) | 5408 (68.8) | 212 (70.9) |
| Age at first test (mean ± SD), yrs | 49.7 ± 17.0 | 47.5 ± 17.0 | 54.5 ± 15.8 |
| Length of followup (mean ± SD), yrs | 9.4 ± 4.9 | 9.2 ± 5.0 | 2.5 ± 0.8 |
| Patients who had rheumatic diseases (at time of testing or over time) | |||
| Rheumatoid arthritis, n (%) | 831 (12.2) | 591 (7.5) | 158 (52.8) |
| Systemic lupus erythematosus, n (%) | 114 (1.7) | 159 (2.0) | 15 (5.0) |
| Polymyalgia rheumatica, n (%) | 246 (3.6) | 190 (2.4) | 28 (9.4) |
| Other connective tissue disease, n (%) | 114 (1.7) | 130 (1.7) | 18 (6.0) |
| Any of the above rheumatic diseases, n (%) | 1147 (16.9) | 943 (12.0) | 182 (60.9) |
| Patients who had rheumatic diseases (among those with positive tests) | |||
| Any of the above rheumatic diseases, n (%) | 456 (64.9) | 431 (23.0) | 42 (95.4) |
RF: rheumatoid factor; ANA: antinuclear antibody; CCP: cyclic citrullinated peptide antibody.