Supplementary Material for: Addition of eGFR and Age Improves the Prognostic Absolute Renal Risk-Model in 1,134 Norwegian Patients with IgA Nephropathy

Background: Predicting outcome in individual patients
with IgA nephropathy (IgAN) is difficult but important. For this
purpose, the absolute renal risk (ARR) model has been developed in a
French cohort to calculate the risk of end-stage renal disease (ESRD)
and death. ARR (0-3) is scored in individual IgAN patients based on the
presence of proteinuria ≥1 g/24 h, hypertension, and severe
histopathological lesions (1 point per risk factor). We have validated
the ARR model in a Norwegian cohort of IgAN patients and tested whether
adding data on initial estimated glomerular filtration rate (eGFR) and
age improved prediction. Methods: IgAN patients diagnosed
between 1988 and 2012 were identified in the Norwegian Kidney Biopsy
Registry, and endpoints were identified by record linkage with the
Norwegian Renal Registry (ESRD) and the Population Registry (deaths). Results:
We identified 1,134 IgAN patients. The mean duration of follow-up was
10.2 years (range 0.0 to 25.7 years). Two hundred and fifty one patients
developed ESRD and there were 69 pre-ESRD deaths. The ARR model
significantly stratified the IgAN cohort according to risk of
ESRD/death. The inclusion of eGFR and age significantly improved the ARR
prognostic model; in the receiver operator characteristics (ROC)
analysis, area under the curve (AUC) at 10-years of follow-up increased
from 0.79 to 0.89, p < 0.001. Conclusions: ARR is a
suitable prognostic model for stratifying IgAN patients according to the
risk of ESRD or death. Including initial eGFR and age in the model
substantially improved its accuracy in our nationwide cohort.

背景：对具有 IgA 肾病（IgAN）的个体患者进行预后预测是一项艰巨但至关重要的任务。为此，研究者们在法国队列中开发了一种绝对肾脏风险（ARR）模型，以计算终末期肾病（ESRD）和死亡的风险。ARR（0-3）评分基于单个 IgAN 患者的蛋白尿（≥1 g/24 h）、高血压和严重组织病理学病变（每项风险因素1分）的存在情况。我们已在挪威 IgAN 患者队列中验证了 ARR 模型，并测试了添加初始估算肾小球滤过率（eGFR）和年龄数据是否能够提高预测精度。方法：在挪威肾脏活检登记处确定了1988年至2012年间诊断的 IgAN 患者，并通过与挪威肾脏登记处（ESRD）和人口登记处（死亡）的记录链接识别终点。结果：我们确定了1134例 IgAN 患者。平均随访时间为10.2年（范围0.0至25.7年）。251名患者发展为 ESRD，有69名患者在 ESRD 前死亡。ARR 模型根据 ESRD 或死亡风险显著分层了 IgAN 队列。将 eGFR 和年龄纳入模型显著提高了 ARR 预测模型的准确性；在接收者操作特征（ROC）分析中，10年随访的曲线下面积（AUC）从0.79增加到0.89，p < 0.001。结论：ARR 是一种适合根据 ESRD 或死亡风险对 IgAN 患者进行分层的预后模型。在模型中加入初始 eGFR 和年龄数据显著提高了其在我国全国队列中的预测精度。