Estimated Albumin Excretion Rate Versus Urine Albumin-Creatinine Ratio for the Assessment of Albuminuria: A Diagnostic Test Study From the Prevention of Renal and Vascular Endstage Disease (PREVEND) Study

Abstract

Background The albumin-creatinine ratio (ACR) in spot urine samples is recommended for albuminuria screening instead of measured albumin excretion rate (mAER) in 24-hour urine collections. In those with extremes of muscle mass, differences in spot urine creatinine may lead to under- or over-estimation of mAER by ACR. We hypothesized that calculating estimated AER (eAER) using spot ACR and estimated creatinine excretion rate (eCER) may improve albuminuria assessment. Study Design Diagnostic test study. Setting & Participants 2711 community-living individuals from the general population of the Netherlands participating in the Prevention of Renal and Vascular Endstage Disease (PREVEND) Study. Index Test eAER was computed as the product of ACR and eCER. eCER was computed using three previously validated methods (Ix, Ellam, Walser). Reference Test mAER, based on two 24-hour urine collections. Accuracy of the eAER and ACR were defined as the percentage of participants falling within 30% (P30) of mAER. Results The mean age was 49 years, 46% were male, mean eGFR was 84 ± 15 ml/min/1.73 m2 and median mAER was 7.2 (IQR, 5.4–11.0) mg/d. The mean measured CER was 1381 mg/d, the median ACR was 4.9 mg/g. Using the Ix equation, the median eAER was 6.4 mg/d. In the full cohort, eAER was more accurate and less biased compared to ACR (P30: 48.9% vs. 33.6%; bias, −34.2% vs −14.1%, respectively). In subgroup analysis, improvement was most notable in the middle and highest weight tertiles and in males. Using the other methods for eCER produced similar results. Limitations Little ethnic heterogeneity and generally healthy cohort make extension of findings to other races and chronically ill uncertain. Conclusions In a large community-dwelling cohort, eAER was more accurate than ACR in assessing albuminuria.

Measures of Kidney Disease and the Risk of Venous Thromboembolism in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study

“…This could have led to misclassification. The PREVEND study reported that ACR was less accurate and more biased than eAER, 24 because urinary creatinine is influenced by muscle mass, introducing confounding based on non-albuminuric covariates. 25 However, in a sensitivity analysis our results were consistent when utilizing eAER as a predictor.…”

Utilizing Estimated Creatinine Excretion to Improve the Performance of Spot Urine Samples for the Determination of Proteinuria in Kidney Transplant Recipients

“…In the same study, the bias of the eAER calculated by eCER using CKD-EPI formula[13] was higher at 3.8 mg/24 h. This study did not assess any other formulae. Abdelmalek et al[21] also showed improved bias of CKD-EPI (median bias -1.0 mg/g), Fotheringham (-0.9 mg/g) and Walser (-0.8 mg/g) as compared to ACR (-2.3 mg/g). This study also revealed improved accuracy of the above three formulae as compared to ACR.…”

Evaluation of Urinary Indices for Albuminuria and Proteinuria in Patients with Chronic Kidney Disease

“…Thus, the accuracy of ACR and PCR improved after adjusting for muscle mass using eCER. Previous studies have focused on the superiority of eAER over ACR in the accuracy of albuminuria assessment [15,21]. Automated eAER reporting should be applied to expand the use of eAER in clinical practice [10].…”

“…Daily albuminuria and proteinuria were measured from 24-h urine collection, and estimated albumin excretion rate (eAER) and estimated protein excretion rate (ePER) were calculated from ACR and PCR, respectively, by multiplying estimated creatinine excretion rate (eCER) [10,15]. eCER MDRD and eCER CKD-EPI were derived from MDRD and CKD-EPI equation, and eAER MDRD , eAER CKD-EPI , ePER MDRD , and ePER CKD-EPI were calculated to estimate daily proteinuria and albuminuria [12].…”