BACKGROUND: Urine albumin is the primary biomarker for detection and monitoring of kidney damage. Because fixed decision criteria are used to identify patients with increased values, we investigated if commonly used routine measurement procedures gave comparable results. METHODS: Results from 17 commercially available urine albumin measurement procedures were investigated vs an isotope dilution mass spectrometry (IDMS) procedure. Nonfrozen aliquots of freshly collected urine from 332 patients with chronic kidney disease, diabetes, cardiovascular disease, and hypertension were distributed to manufacturers to perform urine albumin measurements according to the respective instructions for use for each procedure. Frozen aliquots were used for measurements by the IDMS procedure. An error model was used to determine imprecision and bias components. RESULTS: Median differences between the largest positive and negative biases vs IDMS were 45%, 37%, and 42% in the concentration intervals of 12-30 mg/L, 31-200 mg/L, and 201-1064 mg/L, respectively. Biases varied with concentration for most procedures and exceeded ± 10% over the concentration interval for 14 of 16 quantitative procedures. Mean biases ranged from -35% to 34% at 15 mg/L. Dilution of samples with high concentrations introduced bias for 4 procedures. The combined CV was >10% for 5 procedures. It was not possible to estimate total error due to dependence of bias on concentration. CVs for sample-specific influences were 0% to 15.2%. CONCLUSIONS: Bias was the dominant source of disagreement among routine measurement procedures. Consequently, standardization efforts will improve agreement among results. Variation of bias with concentration needs to be addressed by manufacturers.
BACKGROUND: Urine albumin is the primary biomarker for detection and monitoring of kidney damage. Because fixed decision criteria are used to identify patients with increased values, we investigated if commonly used routine measurement procedures gave comparable results. METHODS: Results from 17 commercially available urine albumin measurement procedures were investigated vs an isotope dilution mass spectrometry (IDMS) procedure. Nonfrozen aliquots of freshly collected urine from 332 patients with chronic kidney disease, diabetes, cardiovascular disease, and hypertension were distributed to manufacturers to perform urine albumin measurements according to the respective instructions for use for each procedure. Frozen aliquots were used for measurements by the IDMS procedure. An error model was used to determine imprecision and bias components. RESULTS: Median differences between the largest positive and negative biases vs IDMS were 45%, 37%, and 42% in the concentration intervals of 12-30 mg/L, 31-200 mg/L, and 201-1064 mg/L, respectively. Biases varied with concentration for most procedures and exceeded ± 10% over the concentration interval for 14 of 16 quantitative procedures. Mean biases ranged from -35% to 34% at 15 mg/L. Dilution of samples with high concentrations introduced bias for 4 procedures. The combined CV was >10% for 5 procedures. It was not possible to estimate total error due to dependence of bias on concentration. CVs for sample-specific influences were 0% to 15.2%. CONCLUSIONS: Bias was the dominant source of disagreement among routine measurement procedures. Consequently, standardization efforts will improve agreement among results. Variation of bias with concentration needs to be addressed by manufacturers.
Authors: Katharina Brück; Vianda S Stel; Giovanni Gambaro; Stein Hallan; Henry Völzke; Johan Ärnlöv; Mika Kastarinen; Idris Guessous; José Vinhas; Bénédicte Stengel; Hermann Brenner; Jerzy Chudek; Solfrid Romundstad; Charles Tomson; Alfonso Otero Gonzalez; Aminu K Bello; Jean Ferrieres; Luigi Palmieri; Gemma Browne; Vincenzo Capuano; Wim Van Biesen; Carmine Zoccali; Ron Gansevoort; Gerjan Navis; Dietrich Rothenbacher; Pietro Manuel Ferraro; Dorothea Nitsch; Christoph Wanner; Kitty J Jager Journal: J Am Soc Nephrol Date: 2015-12-23 Impact factor: 10.121
Authors: Jenna M Norton; Kaltun Ali; Claudine T Jurkovitz; Krzysztof Kiryluk; Meyeon Park; Kensaku Kawamoto; Ning Shang; Sankar D Navaneethan; Andrew S Narva; Paul Drawz Journal: Clin J Am Soc Nephrol Date: 2019-08-12 Impact factor: 8.237
Authors: Katherine R Tuttle; George L Bakris; Rudolf W Bilous; Jane L Chiang; Ian H de Boer; Jordi Goldstein-Fuchs; Irl B Hirsch; Kamyar Kalantar-Zadeh; Andrew S Narva; Sankar D Navaneethan; Joshua J Neumiller; Uptal D Patel; Robert E Ratner; Adam T Whaley-Connell; Mark E Molitch Journal: Diabetes Care Date: 2014-10 Impact factor: 19.112