Table 1

Baseline characteristics of patients, overall and according to ACPA and RF status

Total (N=970)ACPA/RF status
ACPAneg/RFneg (N=262)ACPApos/RFneg (N=60)ACPAneg/RFpos (N=117)ACPApos/RFpos (n=531)P values
Sociodemographic characteristics
 Female, n (%)752 (77.5)205 (78.2)46 (76.7)88 (75.2)413 (77.8)0.92
 Age, mean (SD)55.8 (13.4)57.3 (13.7)55.9 (12.1)57.6 (11.9)54.6 (13.7)0.02
 Post-secondary education, n (%)
 Missing, n (%)
576 (59.4)
44 (4.5)
165 (63.0)
17 (6.5%)
38 (63.3)
2 (3.3)
64 (54.7)
5 (4.3)
309 (58.2)
20 (3.8)
0.18
 Smoking status, n (%)
  Never433 (44.6)125 (47.7)26 (43.3)46 (39.3)236 (44.4)0.27
  Past348 (35.9)87 (33.2)27 (45.0)47 (40.2)187 (35.2)
  Current148 (15.3)34 (13.0)5 (8.3)19 (16.2)90 (16.9)
  Missing41 (4.2)16 (6.1)2 (3.3)5 (4.3)18 (3.4)
 Rural residential area, n (%)173 (17.8)50 (19.1)11 (18.3)17 (14.5)95 (17.9)0.76
Disease characteristics
 RA duration since diagnosis, mean (SD)5.1 (8.0)4.8 (7.6)6.6 (8.9)3.8 (6.6)5.4 (8.4)0.11
 Early RA (duration ≤1 year since diagnosis),
n (%)
481 (49.6)134 (51.1)25 (41.7)61 (52.1)261 (49.2)0.55
 DAS28-ESR (0–9.4), mean (SD)
 Missing, n (%)
4.2 (1.6)
51 (5.3)
4.3 (1.6)
13 (5.0)
3.8 (1.5)
4 (6.7)
4.1 (1.5)
5 (4.3)
4.3 (1.6)
29 (5.5)
0.10
 TCJ-28 (0–28), mean (SD)6.2 (6.3)7.1 (6.8)4.7 (5.2)5.9 (6.0)5.9 (6.2)0.02
 SJC-28 (0–28), mean (SD)5.3 (4.7)5.7 (4.8)4.5 (4.3)4.8 (4.8)5.3 (4.7)0.16
 PtGA (0–10), mean (SD)
 Missing, n (%)
4.8 (2.8)
28 (2.9)
5.1 (2.8)
8 (3.1)
4.3 (2.8)
0
4.7 (2.6)
5 (4.3)
4.7 (2.8)
15 (2.8)
0.08
 PhGA (0–10), mean (SD)
 Missing, n (%)
4.3 (2.5)
102 (10.5)
4.4 (2.5)
29 (11.1)
3.8 (2.0)
2 (3.3)
3.9 (2.4)
17 (14.5)
4.4 (2.6)
54 (10.2)
0.18
 CDAI (0–76), mean (SD)20.5 (13.6)22.3 (14.0)17.2 (11.6)19.5 (13.0)20.2 (13.7)0.03
 SDAI (0.1–86), mean (SD)
 Missing, n (%)
22.0 (14.1)
92 (9.5)
23.6 (14.6)
18 (6.9)
18.2 (11.6)
8 (13.3)
20.5 (13.5)
8 (6.8)
21.9 (14.1)
58 (10.9)
0.04
 HAQ-DI (0–3), mean (SD)
 Missing, n (%)
1.1 (0.8)
43 (4.4)
1.2 (0.8)
16 (6.1)
0.9 (0.7)
2 (3.3)
1.3 (0.7)
5 (4.3)
1.0 (0.7)
20 (3.8)
0.002
 HAQ-PI (0–10), mean (SD)
 Missing, n (%)
1.4 (0.8)
43 (4.4)
1.5 (0.9)
16 (6.1)
1.4 (0.8)
2 (3.3)
1.6 (0.8)
5 (4.3)
1.3 (0.8)
20 (3.8)
0.002
 Number of comorbidities, mean (SD)
 Missing, n (%)
3.4 (2.5)
41 (4.2)
3.7 (2.4)
16 (6.1)
3.7 (2.5)
2 (3.3)
3.8 (2.4)
5 (4.3)
3.2 (2.5)
18 (3.4)
0.02
Treatment characteristics
 Prior use of bDMARDs, n (%)
 Missing, n (%)
238 (24.5)
13 (1.3)
57 (21.8)
2 (0.8)
20 (33.3)
0
31 (26.5)
1 (0.9)
130 (24.5)
5 (0.9)
0.33
 Prior use of csDMARDs, n (%)
 Missing, n (%)
748 (77.1)
7 (0.7)
205 (78.2)
2 (0.8)
48 (80.0)
0
95 (81.2)
1 (0.9)
400 (75.3)
4 (0.8)
0.47
 Current use of bDMARDs, n (%)196 (20.2)55 (21.0)14 (23.3)30 (25.6)97 (18.3)0.28
 Current use of csDMARDs, n (%)849 (87.5)229 (87.4)51 (85.0)101 (86.3)468 (88.1)0.88
 Current use of MTX, n (%)689 (71.0)171 (65.3)40 (66.7)88 (75.2)390 (73.5)0.06
 Current MTX dose, mg/week, mean (SD)18.9 (5.7)19.6 (5.2)19.1 (5.8)18.0 (5.7)18.8 (6.0)0.21
 Current use of oral steroids169 (19.2)46 (17.6)8 (13.3)13 (11.1)102 (19.2)0.16
 Current steroid dose, mg/day, mean (SD)11.1 (8.7)10.0 (7.1)12.7 (15.2)10.6 (8.4)11.5 (8.9)0.73
 Steroid dose at last visit, mg/day, mean (SD)6.4 (10.2)5.5 (7.2)7.1 (10.9)5.4 (7.5)6.9 (11.8)0.69
  • Bold values indicate statistically significant.

  • ACPA, anticitrullinated protein antibody; bDMARDs, biologic disease-modifying antirheumatic drugs; CDAI, Clinical Disease Activity Index; csDMARDs, conventional synthetic DMARDs; DAS28-ESR, 28-joint Disease Activity Score-erythrocyte sedimentation rate; HAQ-DI, Health Assessment Questionnaire Disability Index; HAQ-PI, Health Assessment Questionnaire Pain Index; MTX, methotrexate; PhGA, physician global assessment; PtGA, patient global assessment; RA, rheumatoid arthritis; RF, rheumatoid factor; SDAI, Simplified Disease Activity Index; SJC-28, 28-joint swollen count; TCJ-28, 28-joint tender count.