BACKGROUND: Evaluating the accuracy of estimated glomerular filtration rate (eGFR) derived from serum creatinine (SCr) and serum cystatin C (SCysC) equations requires gold-standard measures of GFR. However, the influence of imprecise measured GFRs (mGFRs) on estimates of equation error is unknown. STUDY DESIGN: Diagnostic test study. SETTING & PARTICIPANTS: 1,995 participants from the Modification of Diet in Renal Disease (MDRD) Study and African American Study of Kidney Disease and Hypertension (AASK) with at least 2 baseline mGFRs from iodine 125-iothalamate urinary clearances, 1 standardized SCr value, and 1 SCysC value. INDEX TESTS: eGFRs calculated using the 4-variable isotope-dilution mass spectrometry (IDMS)-traceable MDRD Study equation, the Chronic Kidney Disease (CKD) Epidemiology Collaboration (CKD-EPI) SCysC equation, the CKD-EPI SCr-SCysC equation, and mGFRs collected from another prerandomization visit. REFERENCE TESTS: A single reference mGFR, average of 2, and average of 3 mGFRs; additional analysis limited to consistent mGFRs (difference <or=25% from reference mGFR). RESULTS: We found that mGFRs had stable mean values, but substantial variability across visits. Of all mGFRs collected a mean of 62 days apart from the reference visit, 8.0% were outside 30% of the single reference mGFR (1 - P(30)). Estimation equations were less accurate because 12.1%, 17.1%, and 8.3% of eGFRs from the MDRD Study, CKD-EPI SCysC, and CKD-EPI SCr-SCysC equations were outside 30% of the same gold standard (1 - P(30)). However, improving the precision of the reference test from a single mGFR to the average of 3 consistent mGFRs decreased these error estimates (1 - P(30)) to 8.0%, 12.5%, and 3.9%, respectively. LIMITATIONS: Study population limited to those with CKD. CONCLUSIONS: Imprecision in gold-standard measures of GFR contribute to an appreciable proportion of the cases in which eGFR and mGFR differ by >30%. Reducing and quantifying errors in gold-standard measurements of GFR is critical to fully estimating the accuracy of GFR estimates.
RCT Entities:
BACKGROUND: Evaluating the accuracy of estimated glomerular filtration rate (eGFR) derived from serum creatinine (SCr) and serum cystatin C (SCysC) equations requires gold-standard measures of GFR. However, the influence of imprecise measured GFRs (mGFRs) on estimates of equation error is unknown. STUDY DESIGN: Diagnostic test study. SETTING & PARTICIPANTS: 1,995 participants from the Modification of Diet in Renal Disease (MDRD) Study and African American Study of Kidney Disease and Hypertension (AASK) with at least 2 baseline mGFRs from iodine 125-iothalamate urinary clearances, 1 standardized SCr value, and 1 SCysC value. INDEX TESTS: eGFRs calculated using the 4-variable isotope-dilution mass spectrometry (IDMS)-traceable MDRD Study equation, the Chronic Kidney Disease (CKD) Epidemiology Collaboration (CKD-EPI) SCysC equation, the CKD-EPI SCr-SCysC equation, and mGFRs collected from another prerandomization visit. REFERENCE TESTS: A single reference mGFR, average of 2, and average of 3 mGFRs; additional analysis limited to consistent mGFRs (difference <or=25% from reference mGFR). RESULTS: We found that mGFRs had stable mean values, but substantial variability across visits. Of all mGFRs collected a mean of 62 days apart from the reference visit, 8.0% were outside 30% of the single reference mGFR (1 - P(30)). Estimation equations were less accurate because 12.1%, 17.1%, and 8.3% of eGFRs from the MDRD Study, CKD-EPI SCysC, and CKD-EPI SCr-SCysC equations were outside 30% of the same gold standard (1 - P(30)). However, improving the precision of the reference test from a single mGFR to the average of 3 consistent mGFRs decreased these error estimates (1 - P(30)) to 8.0%, 12.5%, and 3.9%, respectively. LIMITATIONS: Study population limited to those with CKD. CONCLUSIONS: Imprecision in gold-standard measures of GFR contribute to an appreciable proportion of the cases in which eGFR and mGFR differ by >30%. Reducing and quantifying errors in gold-standard measurements of GFR is critical to fully estimating the accuracy of GFR estimates.
Authors: Julia Lewis; Tom Greene; Lawrence Appel; Gabriel Contreras; Janice Douglas; Jim Lash; Robert Toto; Fredrick Van Lente; Xuelei Wang; Jackson T Wright Journal: J Am Soc Nephrol Date: 2004-12 Impact factor: 10.121
Authors: J Kyhse-Andersen; C Schmidt; G Nordin; B Andersson; P Nilsson-Ehle; V Lindström; A Grubb Journal: Clin Chem Date: 1994-10 Impact factor: 8.327
Authors: W Greg Miller; Gary L Myers; Edward R Ashwood; Anthony A Killeen; Edward Wang; Linda M Thienpont; Lothar Siekmann Journal: Arch Pathol Lab Med Date: 2005-03 Impact factor: 5.534
Authors: Lesley A Stevens; Josef Coresh; Christopher H Schmid; Harold I Feldman; Marc Froissart; John Kusek; Jerome Rossert; Frederick Van Lente; Robert D Bruce; Yaping Lucy Zhang; Tom Greene; Andrew S Levey Journal: Am J Kidney Dis Date: 2008-03 Impact factor: 8.860
Authors: Navdeep Tangri; Lesley A Inker; Hocine Tighiouart; Eric Sorensen; Vandana Menon; Gerald Beck; Michael Shlipak; Josef Coresh; Andrew S Levey; Mark J Sarnak Journal: J Am Soc Nephrol Date: 2011-12-15 Impact factor: 10.121
Authors: Baback Roshanravan; Minesh Khatri; Cassianne Robinson-Cohen; Greg Levin; Kushang V Patel; Ian H de Boer; Stephen Seliger; John Ruzinski; Jonathan Himmelfarb; Bryan Kestenbaum Journal: Am J Kidney Dis Date: 2012-07-07 Impact factor: 8.860
Authors: Lennart Tonneijck; Marcel H A Muskiet; Mark M Smits; Erik J van Bommel; Hiddo J L Heerspink; Daniël H van Raalte; Jaap A Joles Journal: J Am Soc Nephrol Date: 2017-01-31 Impact factor: 10.121
Authors: Zaid Haddadin; Vivian Lee; Christopher Conlin; Lei Zhang; Kristi Carlston; Glen Morrell; Daniel Kim; John M Hoffman; Kathryn Morton Journal: J Nucl Med Technol Date: 2017-02-02
Authors: Sushrut S Waikar; Casey M Rebholz; Zihe Zheng; Shelley Hurwitz; Chi-Yuan Hsu; Harold I Feldman; Dawei Xie; Kathleen D Liu; Theodore E Mifflin; John H Eckfeldt; Paul L Kimmel; Ramachandran S Vasan; Joseph V Bonventre; Lesley A Inker; Josef Coresh Journal: Am J Kidney Dis Date: 2018-07-18 Impact factor: 8.860
Authors: Tiffany A Freed; Josef Coresh; Lesley A Inker; Douglas R Toal; Regis Perichon; Jingsha Chen; Kelli D Goodman; Qibo Zhang; Jessie K Conner; Deirdre M Hauser; Kate E T Vroom; Maria L Oyaski; Jacob E Wulff; Gudný Eiríksdóttir; Vilmundur Gudnason; Vicente E Torres; Lisa A Ford; Andrew S Levey Journal: Clin Chem Date: 2019-01-15 Impact factor: 8.327
Authors: Lesley A Inker; Christina Wyatt; Rebecca Creamer; James Hellinger; Matthew Hotta; Maia Leppo; Andrew S Levey; Aghogho Okparavero; Hiba Graham; Karen Savage; Christopher H Schmid; Hocine Tighiouart; Fran Wallach; Zipporah Krishnasami Journal: J Acquir Immune Defic Syndr Date: 2012-11-01 Impact factor: 3.731