Baseline characteristics of MTX-R and tREACH cohorts.
| Characteristics | Derivation Cohort, n = 93 | Validation Cohort, n = 247 |
|---|---|---|
| Patient demographics | ||
| Age, yrs, mean (SD) | 51.2 (16.1) | 52.8 (14.2) |
| Female (%) | 72.0 | 69.2 |
| BSA, m2, mean (SD) | 1.9 (0.3) | |
| DAS28-ESR, mean (SD)* | 4.1 (1.4) | 4.7 (1.2) |
| Rheumatoid factor–positive (%)* | 37.3 | 56.1 |
| Anti-CCP–positive (%)* | 38.6 | 59.6 |
| Days of treatment at study visit, mean (SD) | 91.2 (11.8) | 92.9 (9.0) |
| Medication | ||
| MTX dose* | 247 | |
| 10 mg/week (%) | 7.5 | 0.0 |
| 15 mg/week (%) | 91.6 | 0.4 |
| 25 mg/week (%) | 1.1 | 99.6 |
| Intramuscular administration of MTX (%) | 7.1 | 0.0 |
| Other DMARD use (%) | 51.8 | 58.4 |
| HCQ use (%)* | 44.7 | 58.4 |
| SSZ use (%)* | 35.3 | 58.4 |
| Biological use (%) | 1.1 | 0.0 |
| Corticosteroid use (%)* | 12.9 | 89.1 |
| Corticosteroid route of administration (%) | ||
| No corticosteroid | 87.1 | 10.9 |
| Subcutaneous | 2.4 | 29.0 |
| Oral | 10.6 | 60.2 |
| Laboratory variables | ||
| CRP, mg/l, median (IQR) | 7.0 (3.0–13.0) | 8.0 (4.0–20.0) |
| ESR, mm/h, mean (SD) | 23.3 (18.9) | 28.0 (21.4) |
| Albumin, g/l, mean (SD) | 44.1 (3.6) | 43.6 (3.2) |
| Creatinine, mmol/l, mean (SD) | 70.8 (16.5) | 75.9 (16.8) |
| Erythrocyte folate, nmol/l, median (IQR)* | 1075.7 (845.7–1323.0) | 925.5 (679.8–1172.5) |
| Serum folate, nmol/l, median (IQR) | 17.3 (13.0–24.1) | 17.3 (13.4–23.9) |
| eGFR-MDRD, ml/min/1.73m3, mean (SD)* | 88.1 (23.8) | 80.7 (18.0) |
| Vitamin B12, pmol/l, median (IQR) | 281.6 (225.5–376.8) | 290.2 (234.5–403.9) |
| Vitamin B6, nmol/l, median (IQR) | 76.0 (66.0–104.0) | 81.0 (65.0–98.0) |
| Homocysteine umol/l, median (IQR) | 12.4 (9.9–14.6) | 11.3 (9.5–14.4) |
| Lifestyle variables (beverage consumption) | ||
| Alcohol, drinks/mo, median (IQR) | 6.0 (0.0–32.0) | 8.0 (2.0–32.0) |
| Cola, drinks/mo, median (IQR) | 0.0 (0.0–24.0) | 0.0 (0.0–8.0) |
| Coffee, drinks/mo, median (IQR) | 56.0 (24.0–168.0) | 112.0 (40.0–112.0) |
| Tea, drinks/mo, median (IQR) | 56.0 (1.5–56.0) | 40.0 (0.0–56.0) |
↵* Signifies a difference between groups that is p < 0.05. MTX: methotrexate; tREACH: treatment in Rotterdam Early Arthritis Cohort; BSA: body surface area; DAS28: Disease Activity Score at 28 joints; ESR: erythrocyte sedimentation rate; DAS28-ESR: ESR-based DAS28; anti-CCP: anticyclic citrullinated peptide antibodies; DMARD: disease-modifying antirheumatic drug; IQR: interquartile range; eGFR: estimated glomerular filtration rate; MDRD: Modification of Diet in Renal Disease; HCQ: hydroxychloroquine; SSZ: sulfasalazine; CRP: C-reactive protein.