BACKGROUND Validated clinical prediction models to identify children with poor prognosis at the time of juvenile idiopathic arthritis (JIA) diagnosis would be very helpful for tailoring treatments, and avoiding under- or over-treatment. Our objective was to externally validate Nordic clinical prediction models in Canadian patients with JIA. METHODS We used data from 513 subjects at the 3-year follow-up from the Research in Arthritis in Canadian Children emphasizing Outcomes (ReACCh-Out) cohort. The predicted outcomes were non-achievement of remission, severe disease course, and functional disability. The Nordic models were evaluated exactly as published and after fine-tuning the logistic regression coefficients using multiple data splits of the Canadian cohort. Missing data was handled with multiple imputation, and prediction ability was assessed with C-indices. C-index values > 0.7 were deemed to reflect helpful prediction. RESULTS Overall, 81% of evaluable patients did not achieve remission off medications, 15% experienced a severe disease course, and 38% reported disability (CHAQ score > 0). The Nordic model for predicting non-achievement of remission had a C-index of 0.68 (95% CI 0.62-0.74), and 0.74 (0.67-0.80) after fine-tuning. For prediction of severe disease course, it had a C-index of 0.69 (0.61-0.78), and 0.79 (0.68-0.91) after fine-tuning. The fine-tuned Nordic model identified 85% of the cohort as low risk for a severe disease course (< 20% chance) and 7% as high risk (> 60% chance). The Nordic model to predict functional disability had a C-index of 0.57 (0.50-0.63), and 0.51 (0.39-0.63) after fine-tuning. CONCLUSIONS Fine-tuned Nordic models, combining active joint count, physician global assessment of disease activity, morning stiffness, and ankle involvement, predicted well non-achievement of remission and severe disease course in Canadian patients with JIA. The Nordic model for predicting disability could not predict functional disability in Canadian patients.

中文翻译：

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幼年特发性关节炎的严重疾病进程和未实现缓解的预测模型的验证：第2部分：加拿大队列中北欧模型的结果。

背景技术经过验证的临床预测模型可以识别出青少年特发性关节炎（JIA）诊断时预后不良的儿童，这对调整治疗方案，避免治疗不足或过度治疗非常有帮助。我们的目标是从外部验证加拿大JIA患者的北欧临床预测模型。方法我们使用了来自加拿大研究强调关节炎（ReACCh-Out）队列的儿童的3年随访研究中513名受试者的数据。预期的结果是未实现缓解，严重的病程和功能障碍。北欧模型的评估与发布的模型完全相同，并使用加拿大队列的多个数据细分对逻辑回归系数进行了微调。丢失的数据通过多次插补处理，预测能力用C指标评估。C-index值> 0.7被认为反映了有用的预测。结果总体而言，可评估的患者中有81％的患者未实现药物缓解，15％的患者经历了严重的病程，38％的患者报告残疾（CHAQ评分> 0）。预测无法实现缓解的北欧模型在微调后的C指数为0.68（95％CI 0.62-0.74）和0.74（0.67-0.80）。为了预测严重的疾病进程，微调后的C指数为0.69（0.61-0.78），C指数为0.79（0.68-0.91）。精细调整的北欧模型确定了该队列中85％的人为严重疾病病程的低风险（<20％的机会），而7％为高风险（> 60％的机会）。预测功能障碍的北欧模型在微调后具有0.57（0.50-0.63）和0.51（0.39-0.63）的C指数。结论结合主动关节计数，医师对疾病活动，早晨僵硬和脚踝受累的整体评估相结合的微调北欧模型预测，加拿大JIA患者的缓解率和严重病程均无法很好地实现。用于预测残疾的北欧模型无法预测加拿大患者的功能障碍。