Table 1.
Baseline characteristics by disease onset group compared using ANOVA
| Variable | All patients | Concordant MD vs patient-reported RA symptom onset date (<30 days) | Discordant MD vs patient-reported symptom onset date (>30 days) | P value | |
| Patient onset precedes MD date | Patient onset after MD date | ||||
| N | 2683 | 1940 | 497 | 246 | |
| Symptom duration by MD (days), median (IQR) | 166 (138) | 161 (133) | 163 (140) | 213 (144) | <0.001 |
| Symptom duration by patient (days), median (IQR) | 178 (163) | 160 (135) | 373 (430) | 132 (126) | <0.001 |
| Age, years, mean (SD) | 54 (15) | 55 (15) | 52 (16) | 54 (16) | 0.003 |
| Female (%) | 1911 (71) | 1375 (71) | 356 (72) | 180 (73) | 0.738 |
| Caucasian (%) | 2179 (81) | 1598 (82) | 391 (79) | 190 (77) | 0.042 |
| Education >high school (%) | 1454 (56) | 1045 (56) | 277 (58.1) | 134 (57) | 0.725 |
| Income >US$50 000 (%) | 805 (45) | 559 (45) | 168 (43) | 174 (45) | 0.755 |
| Smoking (%) | |||||
| Never | 1177 (44) | 834 (43) | 230 (46) | 113 (46) | 0.370 |
| Past smoker | 1030 (38) | 755 (39) | 182 (37) | 93 (38) | 0.594 |
| Current smoker | 465 (17) | 341 (18) | 84 (17) | 40 (16) | 0.822 |
| # of comorbidities | 2 (2) | 2 (2) | 2 (2) | 2 (2) | 0.715 |
| Fibromyalgia (%) | 57 (2) | 35 (2) | 17 (3) | 5 (2) | 0.085 |
| Osteoarthritis (%) | 314 (12) | 225 (12) | 61 (12) | 28 (11) | 0.909 |
| 2010 ACR criteria (%) | 2052 (76) | 1488 (77) | 354 (73) | 200 (81) | 0.047 |
| RF positive (%) | 1402 (59) | 994 (57) | 259 (62) | 149 (69) | 0.001 |
| ACPA positive (%) | 1005 (53) | 739 (52) | 166 (52) | 100 (60) | 0.162 |
| ACPA titre | 87 (139) | 82 (135) | 101 (136) | 110 (167) | 0.009 |
| Erosions (%) | 522 (20) | 376 (19) | 95 (19) | 51 (21) | 0.851 |
| DAS28 | 4.9 (1.5) | 4.9 (1.5) | 4.7 (1.4) | 4.9 (1.4) | 0.015 |
| Swollen joint count (0–28) | 7 (6) | 7 (6) | 6 (6) | 7 (6) | 0.010 |
| Tender joint count (0–28) | 8 (7) | 8 (7) | 8 (7) | 8 (6) | 0.204 |
| HAQ-DI (0–3) | 1 (1) | 1 (1) | 1 (1) | 1 (1) | 0.085 |
| ESR | 27 (22) | 27 (23) | 24 (20) | 27 (22) | 0.006 |
| CRP | 14 (18) | 14 (19) | 12 (16) | 16 (20) | 0.024 |
| MD global score (0–10) | 4.6 (2.5) | 4.6 (2.5) | 4.7 (2.5) | 5.1 (2.5) | 0.003 |
| Patient global score (0–10) | 5.7 (3.0) | 5.7 (2.9) | 5.6 (3.0) | 5.9 (2.9) | 0.398 |
| CDAI | 25 (14) | 26 (14) | 24 (14) | 26 (14) | 0.153 |
| SDAI | 27 (15) | 27 (15) | 26 (15) | 27 (14) | 0.202 |
| Baseline oral steroid (%) | 777 (29) | 606 (31) | 112 (22) | 59 (24) | <0.001 |
| Baseline parenteral steroid (%) | 740 (28) | 542 (28) | 132 (27) | 66 (27) | 0.797 |
| Oral steroid at 3 months (%) | 633 (24) | 479 (25) | 102 (21) | 52 (21) | 0.095 |
| Parenteral steroid at 3 months | 321 (12) | 220 (11) | 61 (12) | 40 (16) | 0.079 |
| Initial RA treatment (%) | |||||
| MTX monotherapy | 725 (27) | 1517 (27) | 144 (29) | 64 (26) | 0.543 |
| MTX combination | 1062 (40) | 798 (41) | 162 (33) | 102 (42) | 0.002 |
| Other DMARDs | 494 (18) | 355 (18) | 99 (20) | 40 (16) | 0.466 |
| Biologic | 49 (2) | 37 (2) | 10 (2) | 2 (1) | 0.455 |
| None of the above | 353 (13) | 233 (12) | 82 (16) | 38 (15) | 0.016 |
| RA treatment at 3 months (%) | |||||
| MTX monotherapy | 608 (23) | 432 (22) | 128 (26) | 48 (20) | 0.113 |
| MTX combination | 1201 (45) | 901 (46) | 185 (37) | 115 (47) | 0.001 |
| Other DMARDs | 433 (16) | 305 (16) | 90 (18) | 38 (15) | 0.415 |
| Biologic | 104 (4) | 77 (4) | 19 (4) | 8 (3) | 0.858 |
| None of the above | 337 (13) | 225 (12) | 75 (15) | 37 (15) | 0.052 |
Results are in mean (SD) if not specified otherwise.
Statistically significant values are indicated in bold.
ACPA, anticitrullinated protein antibodies; ACR, American College of Rheumatology; ANOVA, analysis of variance; CDAI, Clinical Disease Activity Index; CRP, C reactive protein; DAS28, Disease Activity Score based on 28 joint count; DMARD, disease-modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; HAQ-DI, Health Assessment Questionnaire-Disability Index; MD, medical doctor; MTX, methotrexate; RF, rheumatoid factor; SDAI, Simplified Disease Activity Index.