Table 1.
Distribution of candidate predictors in development (CPRD Gold) and validation (CPRD Aurum) cohorts. Values are number (percentage) unless stated otherwise
| Predictors | Development cohort (n=13 110) | Validation cohort (n=23 999) |
|---|---|---|
| Mean (SD) age (years) | 56.8 (14.8) | 57.4 (14.7) |
| Female sex | 8278 (63.1) | 15 252 (63.6) |
| Methotrexate dose: | ||
| Median (interquartile range) dose (mg/week) | 15 (10-20) | 15 (12.5 20) |
| Missing data | 1053 (8.0) | 1537 (6.4) |
| Body mass index: | ||
| <18.5 | 198 (1.5) | 353 (1.5) |
| 18.5-24.9 | 3586 (27.4) | 6495 (27.1) |
| 25.0-29.9 | 4402 (33.6) | 7712 (32.1) |
| ≥30 | 4038 (30.8) | 6881 (28.7) |
| Missing data | 886 (6.8) | 2558 (10.7) |
| Current smoker: | ||
| No* | 10 311 (78.7) | 19 555 (81.5) |
| Yes | 2799 (21.4) | 4444 (18.5) |
| Alcohol consumption (units/week): | ||
| Non-drinker | 1143 (8.7) | 4406 (18.4) |
| Low (1-14) | 6383 (48.7) | 10 228 (42.6) |
| Moderate (15-21) | 508 (3.9) | 1331 (5.6) |
| Hazardous (>21) | 722 (5.5) | 1458 (6.1) |
| Former drinker | 2767 (21.1) | 2646 (11.0) |
| Missing data | 1587 (12.1) | 3930 (16.4) |
| Inflammatory conditions: | ||
| Rheumatoid arthritis | 8097 (61.8) | 15 079 (62.80) |
| Psoriasis or psoriatic arthritis | 3150 (24.0) | 5084 (21.2) |
| Polymyalgia rheumatica or giant cell arteritis | 1091 (8.3) | 2275 (9.5) |
| Connective tissue diseases† | 296 (2.3) | 727 (3.0) |
| Other seronegative spondyloarthritis‡ | 476 (3.6) | 834 (3.5) |
| Comorbidities: | ||
| Diabetes mellitus | 1700 (13.0) | 2689 (11.2) |
| Chronic kidney disease stage 3 | 973 (7.4) | 2076 (8.7) |
| Drugs: | ||
| Hydroxychloroquine | 1968 (15.0) | 4984 (20.8) |
| 5-aminosalicylate or sulfasalazine | 2067 (15.8) | 3080 (12.8) |
| Other glucocorticoid sparing drugs§ | 181 (1.4) | 342 (1.4) |
| Statin | 2833 (21.6) | 5277 (22.0) |
| NSAID or high dose aspirin (≥ 300 mg/day) | 4888 (37.3) | 7471 (31.1) |
| Paracetamol (acetaminophen) | 2173 (16.6) | 3620 (15.1) |
| Proton pump inhibitor | 5870 (44.8) | 10 687 (44.5) |
| Antiepileptic¶ | 118 (0.9) | 239 (1.0) |
| Blood test abnormalities: | ||
| Cytopenia or raised liver enzyme levels within first six months of first primary care methotrexate prescription | 2512 (19.2) | 4429 (18.5) |
| Median (interquartile range) follow-up (years) | 2.35 (0.91-4.83) | 2.73 (1.05-5.00) |
| Outcome events | 854 (6.5) | 1486 (6.2) |
CPRD=Clinical Practice Research Datalink; NSAID=non-steroidal anti-inflammatory drug.
One unit of alcohol equals 10 mL or 8 g of pure alcohol.
*
Includes non-smokers, former smokers, and smoking status not available.
†
Includes lupus, systemic sclerosis, myositis, and small vessel vasculitis.
‡
Includes ankylosing spondylitis, reactive arthritis, and inflammatory bowel disease associated inflammatory arthritis.
§
Includes leflunomide, azathioprine, 6-mercaptopurine, ciclosporin, tacrolimus, and mycophenolate mofetil.
¶
Includes carbamazepine, levetiracetam, and valproate.