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Table 1 Baseline characteristics of incident rheumatoid arthrits cases included in EIRA

From: Parity influences the severity of ACPA-negative early rheumatoid arthritis: a cohort study based on the Swedish EIRA material

  All women (n = 1237) ACPA negative ACPA positive
Aged 18–44 (n = 103) Aged 45–70 (n = 331) Aged 18–44 (n = 230) Aged 45–70 (n = 573)
Mean age, years (SD) 51.5 (12.8) 32.9 (7.0) 58.8 (6.6) 34.3 (7.4) 57.6 (7.0)
Parous, n (%) 1009 (81.6) 68 (66.0) 292 (88.2) 135 (58.7) 514 (89.7)
Nulliparous, n (%) 228 (18.4) 35 (34.0) 39 (11.8) 95 (41.3) 59 (10.3)
Mean time between last birth to symptom onset, years (SD) 24.7 (12.1) 6.8 (4.7) 29.8 (8.1) 7.2 (5.4) 28.8 (9.2)
Mean age at first birth, years (SD) 24 (4.9) 26 (5.3) 24 (4.9) 26 (4.6) 24 (4.8)
Mean number of children (SD) 2.2 (0.9) 1.9 (0.5) 2.4 (0.9) 2.3 (1.2) 2.2 (1.0)
Median DAS28 at inclusion, years (SD) 5.4 (1.2) 5.2 (1.1) 5.6 (1.2) 5.3 (1.1) 5.4 (1.2)
Median HAQ at inclusion (SD) 1.0 (0.6) 1.0 (0.5) 1.1 (0.6) 1.0 (0.6) 1.1 (0.6)
Ever smokers, n (%) 823 (66.7) 59 (57.3) 202 (61.2) 126 (55.0) 436 (76.2)
University degree, n (%) 318 (25.7) 31 (30.1) 85 (25.7) 82 (35.7) 120 (21.0)
Ever use of oral contraceptives before symptom onset, n (%) 807 (65.6) 89 (89.0) 195 (59.1) 185 (81.1) 338 (59.1)
Received DMARD at inclusion, n (%) 1109 (87) 91 (87) 304 (90) 190 (87) 522 (89)
Received prednisolone at inclusion, n (%) 476 (37) 32 (29) 133 (38) 70 (31) 241 (40)
  1. ACPA Anti-citrullinated protein antibody, DAS28 Disease activity score 28, DMARD Disease-modifying antirheumatic drug, EIRA Epidemiological Investigation of Rheumatoid Arthritis, HAQ Health assessment questionnaire, SD Standard deviation