BACKGROUND The grading of urinary tract dilatation (UTD) on postnatal sonography is a fundamental step to establish rational management for infants with antenatal hydronephrosis (ANH). The aim of this study was to compare the prediction accuracy of UTD grading systems for relevant clinical outcomes. In addition, we propose a refinement of the UTD classification by adding quantitative measurements and evaluate its impact on accuracy. METHODS Between 1989 and 2019, 447 infants diagnosed with isolated AHN were prospectively followed. The events of interest were surgical interventions and kidney injury. Comparison of performance of the grading systems and the impact on the accuracy of a modified UTD classification (including the size of the kidney parenchyma) was assessed by the area under the receiver-operating characteristic curve (AUC). RESULTS Of 447 infants, 131 (29%) underwent surgical intervention and 26 (5.8%) had developed kidney injury. The median follow-up time was 9 years (IQ range, 7-12 years). The performance for detecting the need for surgical intervention was excellent for all grading systems (AUC > 0.90). However, for predicting kidney injury, the modified UTD classification exhibited significant improvement in accuracy (AUC = 0.913, 95%CI, 0.883-0.937) as compared with UTD classification (AUC = 0.887, 95%CI, 0.854-0.915) (P = 0.027). CONCLUSIONS Our study confirms that the hydronephrosis grading systems provide excellent accuracy in discriminating patients who need surgical intervention among infants with AHN. Our findings suggest that the inclusion of kidney parenchymal thickness to UTD classification might increase the accuracy for predicting infants who may develop kidney injury. A higher resolution version of the Graphical abstract is available as Supplementary information.

中文翻译：

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产后尿路扩张分类：提高预测肾损伤的准确性。

背景 产后超声检查尿路扩张 (UTD) 的分级是建立合理管理产前肾积水 (ANH) 婴儿的基本步骤。本研究的目的是比较 UTD 分级系统对相关临床结果的预测准确性。此外，我们建议通过添加定量测量来改进 UTD 分类并评估其对准确性的影响。方法 1989 年至 2019 年间，对 447 名诊断为单纯性 AHN 的婴儿进行了前瞻性随访。感兴趣的事件是手术干预和肾损伤。通过接受者操作特征曲线下面积 (AUC) 评估分级系统的性能和对改进的 UTD 分类（包括肾实质大小）准确性的影响。结果 447 名婴儿中，131 名（29%）接受了手术干预，26 名（5.8%）出现了肾损伤。中位随访时间为 9 年（智商范围为 7-12 年）。对于所有分级系统，检测是否需要手术干预的性能都非常出色（AUC > 0.90）。然而，在预测肾损伤方面，与 UTD 分类 (AUC = 0.887, 95%CI, 0.854-0.915) 相比，改良的 UTD 分类在准确度上显着提高 (AUC = 0.913, 95%CI, 0.883-0.937) (P = 0.027)。结论 我们的研究证实，肾积水分级系统在区分 AHN 婴儿中需要手术干预的患者方面提供了出色的准确性。我们的研究结果表明，将肾实质厚度纳入 UTD 分类可能会提高预测可能发生肾损伤的婴儿的准确性。图形摘要的更高分辨率版本可作为补充信息。