Variable | RA cases (n = 520) | RA-free OA controls (n = 303) | P |
---|---|---|---|
Gender, % female (n) | 83.3 (433) | 80.2 (243) | ns |
Age at inclusion, years (range) | 51.6 ± 11.2 (19 to 80) | 57.9 ± 13.5 (21 to 83) | < 0.0001 |
Age of onset, years | 40.8 ± 12.7 | 50.7 ± 12.8 | < 0.0001 |
Duration of disease, years | 10.8 ± 8.3 | 7.2 ± 6.8 | < 0.0001 |
RF, IU/ml | 149.8 ± 67.2 | - | - |
RF-positive, % (n) | 53.8 (280) | - | - |
anti-CCP antibody, RU/mla | 67.5 ± 53.7 | 1.5 ± 6.4 | < 0.0001 |
anti-CCP positive, % (n)b | 78.6 (239) | 3.2 (4) | < 0.0001 |
CRP, μg/ml | 19.6 ± 23.7 | 5.1 ± 9.2 | < 0.0001 |