Diagnostic Performance of Creatinine-Based Equations for Estimating Glomerular Filtration Rate in Adults 65 Years and Older

Key PointsQuestionAre there differences in performance between equations that estimate glomerular filtration rate in adults 65 years and older? FindingsThis single-center, cross-sectional study included 2247 French adults aged 65 to 90 years and older at a single referral center. When comparing 4 plasma creatinine-based glomerular filtration rate-estimating equations (Chronic Kidney Disease-Epidemiology Collaboration, Lund-Malmo Revised, full age spectrum, and Berlin Initiative Study) with the reference inulin-measuring method, there were no clinically significant differences in terms of bias, precision, or accuracy. MeaningThere do not appear to be performance advantages for the use of any of these equations in persons 65 years and older. This cross-sectional study compares 4 equations used to estimate glomerular filtration rate against measurement of inulin 2247 older French adults with varying degrees of kidney health. ImportanceEstimating glomerular filtration rate (GFR) is useful in many clinical conditions. However, very few studies have evaluated the performance of GFR-estimating equations in older adults at various degrees of kidney impairment. ObjectiveTo determine the performance of plasma-creatinine-based equations Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI), Lund-Malmo Revised, (LMR), full age spectrum (FAS), and Berlin Initiative Study (BIS) 1 in older adults across a broad spectrum of GFRs. Design, Setting, and ParticipantsSingle-center cross-sectional study performed in France including 2247 participants aged 65 to 90 years who underwent inulin GFR measurements from July 1, 2003, to July 30, 2017, for suspected or established renal dysfunction, for renal risk, before kidney donation, or after kidney transplant. Main Outcomes and MeasuresThe main outcome measure was GRF measured by inulin clearance. Equation performance criteria considered bias (difference between estimated and measured GFR), precision (interquartile range of the median difference), and accuracy P-30 (percentage of estimated GFRs lying between [measured GFR - 30% of measured GFR] and [measured GFR + 30% of measured GFR]). ResultsThe mean (SD) age of the 2247 participants was 71.5 (5) years and 1192 (53.0%) were male. The difference in median (95% CI) bias was significant between CKD-EPI vs LMR (-4.0 [-4.0 to -3.5 mL/min/1.73 m(2); P<.001]) and CKD-EPI vs FAS (-2.0 [-3.5 to -2.5] mL/min/1.73 m(2), P<.001) but not significant between CKD-EPI vs BIS 1 (0.0 [-1.5 to 0.5], P=.07, Mood test). In patients aged 65 to 74 years with measured GFR<45 mL/min/1.73 m(2), the difference in median P-30 (95% CI) was not significant between CKD-EPI vs LMR (P=.08) and CKD-EPI vs FAS (P=.48) but significant vs BIS 1 (P=.004, McNemar test). In subjects 75 years and older, with measured GFR less than 45 mL/min/1.73 m(2), LMR and BIS 1 were more accurate than CKD-EPI and FAS (P-30=74.5 [70.0-79.5] and 73.0 [68.0-78.0] vs 69.0 [64.5-74.0] and 69.0 [65.5-72.0]). In all patients, despite small statistical differences, the performance of CKD-EPI equation was not clinically different from that of LMR, FAS, or BIS 1. Conclusions and RelevanceIn a referral group of patients 65 years and older who had GFR estimated using CDK-EPI, LMR, BIS 1, and FAS equations, a comparison with renal inulin clearance found that none of the equations had a superior diagnostic performance. Each had limitations regarding accuracy.