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Table 3 Prediction model and scores for MTX intolerance

From: Prediction of Methotrexate Intolerance in Juvenile Idiopathic Arthritis: a prospective, observational cohort study

Predictors OR (95%-CI) p-value β a Score b
JIA category      
Oligoarticular (persistent/extended) Reference 0
Polyarticular (RF negative/positive) 4.99 (1.36-18.34) 0.016 0.914 5
Other (systemic/psoriatic/enthesitis) 0.93 (0.16-5.49) 0.935 −0.042 0
ANA Positive 1.98 (0.83-4.68) 0.122 0.387 2
Parent/patient assessment of pain ≤3 cm Reference 0
3-6 cm 2.06 (0.72-5.89) 0.175 0.412 2
>6 cm 0.60 (0.17-2.07) 0.421 −0.288 −1
JADAS-27 ≤5 Reference 0
5-15 0.35 (0.08-1.56) 0.168 −0.599 −3
>15 0.77 (0.14-4.32) 0.766 −0.150 −1
Thrombocytes >350 × 109/L 1.27 (0.49-3.27) 0.621 0.136 1
ALT >12 IU/L 0.39 (0.16-0.96) 0.040 −0.534 −3
Creatinine >50 μmol/L 1.37 (0.33-5.67) 0.665 0.179 1
Interaction term creatinine: JIA category
>50 μmol/L & polyarticular arthritis 0.17 (0.02-1.35) 0.093 −1.022 −5
>50 μmol/L & other JIA category 0.82 (0.07-9.74) 0.878 −0.110 −1
Constant     −0.039 7
C-statistic 77.5%
C-statistic (optimism-corrected by bootstrap) 66.7%
Hosmer-Lemeshow test (p-value) 0.705
  1. Abbreviations: ALT, alanine aminotransferase; ANA, anti-nuclear antibody; CI, confidence interval; JADAS, juvenile arthritis disease activity score; JIA, juvenile idiopathic arthritis; MTX, methotrexate; OR, odds ratio; RF, rheumatoid factor.
  2. aThese are shrunk coefficients (by factor 0.5688) to correct for overfitting.
  3. bShrunk coefficients were multiplied by 5 and rounded off to the nearest integer. The constant was adjusted to obtain the minimum score of 0.