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 IIa
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)

aACPA: anticitrullinated peptide autoantibody, BMI: body mass index, CCP: cyclic citrullinated peptide, NHS: Nurses’ Health Study, NHSII: Nurses’ Health Study II, RA: rheumatoid arthritis. bPack-years among ever smokers only.

Arkema et al.

Arkema et al. Arthritis Research & Therapy 2013 15:R159   doi:10.1186/ar4342

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