title: Reproducibility of albuminuria in type 2 diabetic subjects. Findings from the Renal Insufficiency And Cardiovascular Events (RIACE) study.
abstract: 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 (ROC(AUC) 0.926; 95% confidence interval: 0.915-0.937) and macroalbuminuria (ROC(AUC) 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.
authors: Department of Clinical and Molecular Medicine, La Sapienza University, Rome, Italy. giuseppe.pugliese@uniroma1.it
authors: Giuseppe
authors: G
authors: Pugliese
authors: Anna
authors: A
authors: Solini
authors: Cecilia
authors: C
authors: Fondelli
authors: Roberto
authors: R
authors: Trevisan
authors: Monica
authors: M
authors: Vedovato
authors: Antonio
authors: A
authors: Nicolucci
authors: Giuseppe
authors: G
authors: Penno
mesh_terms: D000368:Aged; D000419:Albuminuria / Q000652:urine*; D002318:Cardiovascular Diseases; D003924:Diabetes Mellitus, Type 2 / Q000652:urine*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D051437:Renal Insufficiency; D015203:Reproducibility of Results