Estimating Equations for Glomerular Filtration Rate in the Era of Creatinine Standardization A Systematic Review

mated glomerular filtration rate (GFR) by using serum creatinine assays traceable to a standard reference material. Purpose: To review the performance of GFR estimating equations to inform the selection of a single equation by laboratories and the interpretation of estimated GFR by clinicians. Data Sources: A systematic search of MEDLINE, without language restriction, between 1999 and 21 October 2011. Study Selection: Cross-sectional studies in adults that compared the performance of 2 or more creatinine-based GFR estimating equations with a reference GFR measurement. Eligible equations were derived or reexpressed and validated by using creatinine mea-surements traceable to the standard reference material. Data Extraction: Reviewers extracted data on study population characteristics, measured GFR, creatinine assay, and equation per-formance