Journal Article

Reproducibility of albuminuria in type 2 diabetic subjects. Findings from the Renal Insufficiency And Cardiovascular Events (RIACE) study

Giuseppe Pugliese, Anna Solini, Cecilia Fondelli, Roberto Trevisan, Monica Vedovato, Antonio Nicolucci and Giuseppe Penno

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 26, issue 12, pages 3950-3954
Published in print December 2011 | ISSN: 0931-0509
Published online March 2011 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/gfr140
Reproducibility of albuminuria in type 2 diabetic subjects. Findings from the Renal Insufficiency And Cardiovascular Events (RIACE) study

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Background. Measurement of urinary albumin excretion (UAE) shows important intra-individual variability suggesting the need for multiple assessments. This study aimed at investigating the reproducibility of UAE in type 2 diabetes.

Methods. UAE was obtained from two to three samples collected in a 3- to 6-month period from 4062 of the 15 773 type 2 diabetic subjects participating in the Renal Insufficiency And Cardiovascular Events (RIACE) Italian Multicentre Study in 2007–08. UAE was assessed as albumin excretion rate (AER) in 24-h urine collections from 833 subjects and albumin:creatinine ratio (A/C) in early-morning urine samples from 3229 patients. Albuminuria was measured by immunonephelometry or immunoturbidimetry.

Results. The median coefficient of variation (CV) was 32.5% (interquartile range: 14.3–58.9). Concordance rate between a single UAE and the geometric mean of multiple measurements was 94.6% for normoalbuminuria, 83.5% for microalbuminuria, 91.1% for macroalbuminuria and 90.6% for albuminuria (micro + macro). CV was significantly higher (P < 0.01) for AER measurement than for A/C and with immunoturbidimetry than with immunonephelometry, whereas concordance rates were similar between the two modalities of urine collection and the two assay methods. Receiver-operating characteristic (ROC) plots demonstrated a good performance of single UAE in predicting the geometric mean of multiple measures at the cut-off level of both microalbuminuria (ROCAUC 0.926; 95% confidence interval: 0.915–0.937) and macroalbuminuria (ROCAUC 0.950; 95% confidence interval: 0.927–0.973).

Conclusions. Data from this large cohort indicate that, in type 2 diabetic subjects, a single UAE value, thought to be encumbered with high intra-individual variability, is an accurate predictor of nephropathy stage for clinical and epidemiological purposes.

Keywords: albuminuria; diabetic nephropathy; type 2 diabetes

Journal Article.  2421 words.  Illustrated.

Subjects: Nephrology

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