• Wei Wang, Bessie A Young, Tibor Fülöp, Ian H de Boer, L Ebony Boulware, Ronit Katz, Adolfo Correa, and Michael E Griswold.
• Center of Biostatistics and Bioinformatics (WW, MEG), University of Mississippi Medical Center, Jackson, Mississippi; Center for Innovation and Hospital and Specialty Care (BAY, IHdB, RK), Veterans Affairs Puget Sound Health Care System, Seattle, Washington; Division of Nephrology and Kidney Research Institute (BAY, IHdB), University of Washington, Seattle, Washington; Department of Medicine (TF, AC), University of Mississippi Medical Center, Jackson, Mississippi; and Department of Medicine (LEB), Duke University, Durham, North Carolina.
• Am. J. Med. Sci. 2015 May 1; 349 (5): 379384379-84.

BackgroundThe calibration to isotope dilution mass spectrometry-traceable creatinine is essential for valid use of the new Chronic Kidney Disease Epidemiology Collaboration equation to estimate the glomerular filtration rate.MethodsFor 5,210 participants in the Jackson Heart Study (JHS), serum creatinine was measured with a multipoint enzymatic spectrophotometric assay at the baseline visit (2000-2004) and remeasured using the Roche enzymatic method, traceable to isotope dilution mass spectrometry in a subset of 206 subjects. The 200 eligible samples (6 were excluded, 1 for failure of the remeasurement and 5 for outliers) were divided into 3 disjoint sets-training, validation and test-to select a calibration model, estimate true errors and assess performance of the final calibration equation. The calibration equation was applied to serum creatinine measurements of 5,210 participants to estimate glomerular filtration rate and the prevalence of chronic kidney disease (CKD).ResultsThe selected Deming regression model provided a slope of 0.968 (95% confidence interval [CI], 0.904-1.053) and intercept of -0.0248 (95% CI, -0.0862 to 0.0366) with R value of 0.9527. Calibrated serum creatinine showed high agreement with actual measurements when applying to the unused test set (concordance correlation coefficient 0.934, 95% CI, 0.894-0.960). The baseline prevalence of CKD in the JHS (2000-2004) was 6.30% using calibrated values compared with 8.29% using noncalibrated serum creatinine with the Chronic Kidney Disease Epidemiology Collaboration equation (P < 0.001).ConclusionsA Deming regression model was chosen to optimally calibrate baseline serum creatinine measurements in the JHS, and the calibrated values provide a lower CKD prevalence estimate.

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