Table 5.
Prognostic tests for predicting failure to respond after start methotrexate according to ACR recommendations and cJADAS scores in patients with oligoarticular and polyarticular juvenile idiopathic arthritis
| 3 months | Oligoarticular patients | Polyarticular patients | ||||||
| Rule | Accuracy (%) | Sensitivity (%) | Specificity (%) | Sum (%) | Accuracy (%) | Sensitivity (%) | Specificity (%) | Sum (%) |
| ACR escalation | 62.5 | 10.0 | 86.4 | 96.4 | 57.1 | 86.7 | 44.4 | 131.1 |
| cJADAS >4 | 20.0 | 71.4 | 55.6 | 127.0 | 47.8 | 81.3 | 30.0 | 111.3 |
| cJADAS >5 | 70.8 | 71.4 | 70.6 | 142.0 | 58.1 | 81.3 | 44.4 | 125.7 |
| cJADAS >6 | 68.2 | 33.3 | 81.3 | 114.6 | 64.3 | 81.3 | 53.8 | 135.1 |
| cJADAS >7 | 72.7 | 33.3 | 87.5 | 120.8 | 75.6 | 81.3 | 72.0 | 153.3 |
| cJADAS >8 | 77.3 | 33.3 | 93.8 | 127.1 | 75.0 | 73.3 | 76.0 | 149.3 |
| Correctly not escalated | 75.0 | 70.5 | ||||||
| 6 months | Accuracy (%) | Oligoarticular patients | Accuracy (%) | Polyarticular patients | ||||
| Rule | Sensitivity (%) | Specificity (%) | Sum (%) | Sensitivity (%) | Specificity (%) | Sum (%) | ||
| ACR escalation | 67.7 | 0 | 95.5 | 95.5 | 46.9 | 77.8 | 29.0 | 106.8 |
| cJADAS >2 | 62.1 | 100 | 50.0 | 150.0 | 51.1 | 76.5 | 36.7 | 113.2 |
| cJADAS >3 | 67.9 | 100 | 57.1 | 157.1 | 66.7 | 70.6 | 64.3 | 134.9 |
| cJADAS >4 | 70.4 | 66.7 | 71.4 | 138.1 | 75.6 | 70.6 | 78.6 | 149.2 |
| cJADAS >5 | 74.1 | 66.7 | 76.2 | 142.9 | 72.1 | 56.3 | 81.5 | 137.8 |
| Correctly not escalated | 71.9 | 71.7 | ||||||
The cJADAS as prognostic tests outperformed the ACR recommendations as shown by accuracy, sensitivity and specificity and the sum of the latter two. At 3 months, we were aiming at a high specificity (avoiding overtreatment) and the best performing cut-off values were >5 and >7 for OJIA and PJIA, respectively. At 6 months, we were aiming at a high sensitivity (avoiding undertreatment) and the best performing cut-off values at 6 months were >3 and >4 for OJIA and PJIA, respectively. The percentages of correct physician decisions when not escalated (percentage of patients not escalated at that decision point who at 12 months indeed appeared to be a responder on MTX) are displayed in the row of ‘correctly not escalated’.
ACR, American College of Rheumatology; cJADAS, clinical Juvenile Arthritis Disease Activity Score; OJIA, oligoarticular juvenile idiopathic arthritis; PJIA, polyarticular juvenile idiopathic arthritis.