Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
Kidney Int. 2022 Jun;101(6):1260-1270. doi: 10.1016/j.kint.2022.02.034. Epub 2022 Apr 7.
Albumin-to-creatinine ratio (ACR), the preferred method to quantify proteinuria, can be calculated from urine dipstick protein or protein-to-creatinine ratio (PCR). The performance of calculated vs. measured ACR in predicting kidney failure and death without kidney failure in people with chronic kidney disease (CKD) is unknown. Here, we used population-based data from Alberta, Canada, to identify adults with incident moderate-severe CKD (sustained for more than 90 days) from 2008-04-01 to 2017-03-31, who had same-day measures of ACR and urine dipstick (ACR-dipstick cohort) or PCR (ACR-PCR cohort) in the two years before cohort entry. We followed participants until 2019-03-31 and trained competing risk models of kidney failure and death without kidney failure including age, sex, estimated glomerular filtration rate, diabetes, cardiovascular disease, and either measured or calculated ACR. Model performance was tested in cohorts created using the same algorithm in Manitoba, Canada. The ACR-dipstick and ACR-PCR cohorts included 18,731 and 4,542 people (training cohorts) and 821 and 1,831 people (testing cohorts), respectively. In internal and external testing, there was closer agreement between predictions based on measured vs. PCR-calculated ACR than between those based on measured vs. dipstick-calculated ACR. The dipstick-calculated ACR had higher Brier scores than measured ACR from year three for both outcomes, indicating worsening calibration. Models including measured or calculated ACR had similar discrimination: year one-to-five area under the receiver operating characteristic curve of 83-89% for kidney failure and 69-75% for mortality. Thus, if confirmed in different ethnic groups, calculated ACR can be used for risk predictions when the measured ACR is not available. PCR-calculated ACR may have superior performance to dipstick-calculated ACR.
白蛋白与肌酐比值（ACR）是定量蛋白尿的首选方法，可通过尿试纸蛋白或蛋白与肌酐比值（PCR）计算得出。在患有慢性肾脏病（CKD）的人群中，计算的 ACR 与实测 ACR 预测肾衰竭和无肾衰竭死亡的性能尚不清楚。在这里，我们使用来自加拿大艾伯塔省的基于人群的数据，确定了 2008 年 4 月 1 日至 2017 年 3 月 31 日期间患有持续 90 天以上的中重度 CKD 的成年人（ACR-试纸队列），或在队列入组前两年内进行了同日 ACR 和尿试纸（ACR-试纸队列）或 PCR（ACR-PCR 队列）的检测。我们随访参与者直至 2019 年 3 月 31 日，并使用竞争风险模型对肾衰竭和无肾衰竭死亡进行了训练，包括年龄、性别、估计肾小球滤过率、糖尿病、心血管疾病，以及实测或计算的 ACR。在加拿大马尼托巴省使用相同算法创建的队列中测试了模型性能。ACR-试纸和 ACR-PCR 队列分别包括 18731 人和 4542 人（训练队列）和 821 人和 1831 人（测试队列）。在内部和外部测试中，基于实测与 PCR 计算的 ACR 的预测与基于实测与试纸计算的 ACR 的预测之间的一致性要优于后者。对于两种结局，从第三年开始，试纸计算的 ACR 的 Brier 评分均高于实测 ACR，表明校准情况恶化。包括实测或计算的 ACR 的模型具有相似的区分度：对于肾衰竭，第 1 年至第 5 年的接受者操作特征曲线下面积为 83%-89%；对于死亡率，为 69%-75%。因此，如果在不同的种族群体中得到证实，那么在无法获得实测 ACR 的情况下，计算的 ACR 可用于风险预测。PCR 计算的 ACR 可能比试纸计算的 ACR 具有更好的性能。
