Baseline characteristics
| Patients with RA with fatigue data at disease onset (n=902)* | Non-RA early patients with arthritis with fatigue data at disease onset (n=1540)† | Patients with RA with repeated fatigue data over 8 years (n=626)‡ | |
|---|---|---|---|
| Age at disease onset, mean (SD), years | 56.6 (15.3) | 49.9 (17.4) | 56.5 (15.5) |
| Female, n (%) | 607 (67.3) | 868 (56.4) | 429 (68.5) |
| Inclusion period | 1993–2013 | 1993–2013 | 1993–2007 |
| Symptom duration, median (IQR), weeks | 18.3 (9.3–34.7) | 13.1 (5.1–29.1) | 19.3 (10.7–39.3) |
| Morning stiffness, median (IQR), minutes | 60 (30–120) | 30 (0–60) | 60 (30–120) |
| SJC, median (IQR) | 7 (4–12) | 2 (1–6) | 8 (4–14) |
| TJC, median (IQR) | 4 (7–10) | 4 (2–7) | 8 (5–12) |
| CRP, median (IQR), mg/L | 14 (6–33) | 8 (3–23) | 17 (8–39) |
| Hb, mean (SD), mmol/L | 8.2 (0.8) | 8.4 (0.9) | 8.1 (0.8) |
| ACPA-positive, n (%) | 456 (52.1) | 105 (9.1) | 326 (54.1) |
| RF-positive, n (%) | 516 (57.9) | 228 (15.1) | 364 (59.2) |
| SHS, median (IQR) | 5 (2–11) | N/A | 5 (2–11) |
| HAQ, median (IQR) | 1 (0.6–1.5) | 0.6 (0.3–1.0) | 1 (0.6–1.5) |
*Symptom duration was missing in 54 patients, morning stiffness in 78 patients, SJC in 14 patients, TJC in 236 patients, CRP in 30 patients, Hb in 18 patients, ACPA-status in 27 patients, RF-status in 11 patients, SHS in 372 patients and HAQ in 108 patients.
†Symptom duration was missing in 113 patients, morning stiffness in 188 patients, SJC is 37 patients, TJC in 467 patients, CRP in 78 patients, Hb in 43 patients, ACPA-status in 392 patients, RF-status in 31 patients and HAQ in 221 patients. The radiographs of the patients without RA were not SHS scored.
‡Symptom duration was missing in 37 patients, morning stiffness in 19 patients, SJC in 4 patients, TJC in 334 patients, CRP in 36 patients, The missing values were imputed for the analyses of associations between fatigue and other variables within RA. Hb in 16 patients, ACPA-status in 23 patients, RF-status in 11 patients, SHS in 19 patients and HAQ in 104 patients.
ACPA, anticitrullinated peptide antibody; CRP, C reactive protein; HAQ, Health Assessment Questionnaire; Hb, haemoglobin; N/A, not applicable; RA, rheumatoid arthritis; RF, IgM rheumatoid factor; SHS, Sharp-van der Heijde score; SJC, 66-swollen joint count; TJC, 68-tender joint count.