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Table 1 Baseline characteristics of patients with rheumatoid arthritis included in the cohorts studied

From: The prevalence of ACPA is lower in rheumatoid arthritis patients with an older age of onset but the composition of the ACPA response appears identical

Variable Leiden EAC BARFOT ESPOIR Umeå Lund
Total number of patients 1244 839 632 459 147
Age, mean (SD) 56.6 (15.5) 56.7 (15.4) 48.9 (12.2) 53.9 (14.5) 50.7 (11.5)
Female, n (%) 827 (66.5) 538 (64.1) 484 (76.6) 321 (69.9) 98 (66.7)
Symptom durationa (weeks), median (IQR) 18.3 (9–36) 26.1 (17–39) 21.4 (13–33) 28.0 (16–39) 43.3 (28–61)
Smoking at baseline, n (%) 308 (25.9) 227 (27.1) 137 (21.7) 107 (23.9) 39 (30.7)
ACPA+, n (%) 638 (52.8) 418 (55.0) 291 (46.0) 339 (73.9) 114 (80.3)
RF+, n (%) 715 (58.0) 453 (59.6) 344 (54.4) 362 (79.0) 115 (81.0)
Anti-CarP+, n (%) 474 (42.3) 280 (34.7) NA NA NA
ESR (mm/h), median (IQR) 31 (16–50) 30 (15–50) 23 (12–41) 22 (12–39) 28 (13–50)
CRP (mg/L), median (IQR) 14 (6–35.5) 19 (7–47.5) 10 (3–26) 10 (8–25) 15 (0–45.5)
SJC, median (IQR) 5 (3–10) 10 (6–14) 7 (4–11) 6 (3–10) 6 (3–10)
TJC, median (IQR) 6 (2–11) 7 (3–12) 8 (4–14) 5 (2–10) 7 (4–11)
  1. n number of patients, SD standard deviation, IQR interquartile range, ACPA anti-citrullinated protein antibodies, RF rheumatoid factor, anti-CarP antibodies ESR erythrocyte sedimentation rate, CRP C-reactive protein, TJC tender joint count based on 68 joints (Leiden EAC) or on 28 joints (BARFOT, ESPOIR, Umeå) or Ritchie index (Lund), SJC swollen joint count based on 66 joints (Leiden EAC) or on 28 joints (BARFOT, ESPOIR, Umeå) or on 50 joints (Lund), NA not available
  2. aTime between symptom onset and inclusion in cohort