. 2020 Jan 15;22:10. doi: 10.1186/s13075-019-2091-8

Table 1.

The original Canadian and Nordic prediction models for juvenile idiopathic arthritis

Source	Outcome predicted	Calculate A	Use A to calculate chance of outcome (%)
Guzman et al., Canada 2017 [7]	Severe disease course, defined by trajectory of quality of life, pain, active joint count, medication requirements, and medication side effects over the 5 years after diagnosis	A = − 2.92 + 0.18 × (active joint count at baseline) − 1.23 × (psoriatic arthritis) − 1.14 × (oligoarthritis) − 0.49 × (RF-negative polyarthritis) + 0.75 × (upper limb joint involvement) − 0.88 × (symmetric joint involvement) + 1.31 × (RF positivity) − 1.42 × (subtalar joint involvement) − 0.31 × (finger joint involvement) + 0.84 × (cervical spine involvement) + 0.48 × (ankle joint involvement) + 0.56 × (presence of morning stiffness) + 0.06 × (hip involvement) + 1.50 × (temporal mandibular joint involvement) + 0.54 × (mid-foot involvement) + 0.86 × (presence of enthesitis)	[e^A/(1 + e^A)] × 100 where e^A is the natural antilogarithm of A
Rypdal et al., Norway 2018 [8]	Non-achievement of remission 8 years after onset	A = − 1.58 + 0.04 × (cumulative joint count within 6 months of onset) + 0.03 × (ESR in mm/h) − 0.07 × (CRP > 10 mg/L) + 1.16 × (morning stiffness > 15 min) + 0.16 × (physician global assessment) + 1.25 × (ANA positive) + 1.37 × (B27 positive) + 1.10 × (ankle joint arthritis)	[e^A/(1 + e^A)] × 100 where e^A is the natural antilogarithm of A
Rypdal et al., Norway 2018 [8]	Functional disability (CHAQ > 0) 8 years after onset	A = − 1.68 − 0.02 × (cumulative joint count within 6 months of onset) + 0.01 × (ESR in mm/h) − 0.20 × (CRP > 10 mg/L) + 1.03 × (morning stiffness > 15 min) − 0.40 × (physician global assessment VAS) + 1.21 × (finger joint arthritis) + 0.77 × (pain VAS)	[e^A/(1 + e^A)] × 100 where e^A is the natural antilogarithm of A

Source

Outcome predicted

Calculate A

Use A to calculate chance of outcome (%)

Guzman et al., Canada 2017 [7]

Severe disease course, defined by trajectory of quality of life, pain, active joint count, medication requirements, and medication side effects over the 5 years after diagnosis

A = − 2.92 + 0.18 × (active joint count at baseline) − 1.23 × (psoriatic arthritis) − 1.14 × (oligoarthritis) − 0.49 × (RF-negative polyarthritis) + 0.75 × (upper limb joint involvement) − 0.88 × (symmetric joint involvement) + 1.31 × (RF positivity) − 1.42 × (subtalar joint involvement) − 0.31 × (finger joint involvement) + 0.84 × (cervical spine involvement) + 0.48 × (ankle joint involvement) + 0.56 × (presence of morning stiffness) + 0.06 × (hip involvement) + 1.50 × (temporal mandibular joint involvement) + 0.54 × (mid-foot involvement) + 0.86 × (presence of enthesitis)

[e^A/(1 + e^A)] × 100

where e^A is the natural antilogarithm of A

Rypdal et al., Norway 2018 [8]

Non-achievement of remission 8 years after onset

A = − 1.58 + 0.04 × (cumulative joint count within 6 months of onset) + 0.03 × (ESR in mm/h) − 0.07 × (CRP > 10 mg/L) + 1.16 × (morning stiffness > 15 min) + 0.16 × (physician global assessment) + 1.25 × (ANA positive) + 1.37 × (B27 positive) + 1.10 × (ankle joint arthritis)

[e^A/(1 + e^A)] × 100

where e^A is the natural antilogarithm of A

Rypdal et al., Norway 2018 [8]

Functional disability (CHAQ > 0) 8 years after onset

A = − 1.68 − 0.02 × (cumulative joint count within 6 months of onset) + 0.01 × (ESR in mm/h) − 0.20 × (CRP > 10 mg/L) + 1.03 × (morning stiffness > 15 min) − 0.40 × (physician global assessment VAS) + 1.21 × (finger joint arthritis) + 0.77 × (pain VAS)

[e^A/(1 + e^A)] × 100

where e^A is the natural antilogarithm of A

RF rheumatoid factor, ESR erythrocyte sedimentation rate, CRP C-reactive protein, ANA antinuclear antibody test, B27 human leucocyte antigen B27, VAS visual analogue scale from 0 to 10 with 10 indicating worse values