Table 1 Characteristics of preclinical rheumatoid arthritis cases and matched controls at time of blood collection in the Nurses’ Health Study and Nurses’ Health Study II a
Characteristics | RA cases (N = 192) | Matched controls (N = 567) |
|---|---|---|
Cohort, n (%) | ||
NHS | 136 (70.8) | 405 (71.4) |
NHSII | 56 (29.2) | 162 (28.6) |
Caucasian, n (%) | 190 (99.0) | 556 (98.1) |
Mean age at blood collection, years (SD) | 52.3 (8.0) | 52.4 (8.1) |
Never smoker, n (%) | 83 (43.2) | 279 (49.2) |
Current smoker, n (%) | 33 (17.2) | 82 (14.5) |
Past smoker, n (%) | 76 (39.6) | 206 (36.3) |
Mean pack-years of smokingb (SD) | 23.1 (16.4) | 20.8 (18.8) |
Mean alcohol intake, g/day (SD) | 4.2 (5.6) | 5.7 (8.9) |
Mean BMI, kg/m2 (SD) | 26.1 (5.0) | 25.0 (4.4) |
Premenopausal, n (%) | 65 (33.9) | 193 (34.0) |
Parous, n (%) | 175 (91.1) | 511 (90.1) |
Irregular menses, n (%) | 32 (16.7) | 56 (9.9) |
Positive for any ACPA, n (%) | 48 (25.0) | 38 (6.7) |
Positive for anti-CCP, n (%) | 23 (12.0) | 0 (0) |
Mean age at RA diagnosis, years (SD) | 59.9 (9.9) | |
Mean time to RA onset, months (SD) | 91.1 (53.6) | |
Median time to RA onset, months (IQR) | 87.5 (92.0) | |
Morning stiffness, n (%) | 143 (74.5) | |
Arthritis three or more joint areas, n (%) | 176 (91.7) | |
Hand arthritis, n (%) | 191 (99.5) | |
Symmetric arthritis, n (%) | 188 (97.9) | |
Nodules, n (%) | 21 (10.9) | |
Erosions, n (%) | 43 (22.4) |