TY - JOUR
T1 - Accuracy of a GFR estimating equation over time in people with a wide range of kidney function
AU - Padala, Smita
AU - Tighiouart, Hocine
AU - Inker, Lesley A.
AU - Contreras, Gabriel
AU - Beck, Gerald J.
AU - Lewis, Julia
AU - Steffes, Michael
AU - Rodby, Roger A.
AU - Schmid, Christopher H.
AU - Levey, Andrew S.
N1 - Funding Information:
Support: National Kidney Foundation Fellowship Award , Clinical and Translational Science Institute , National Institutes of Health UO1 DK 053869 , UO1 DK 067651 , and UO1 DK 35073 ; K23 DK 081017 .
PY - 2012/8
Y1 - 2012/8
N2 - Background: Change in glomerular filtration rate (GFR) is important for clinical decision making. GFR estimates from serum creatinine level provide an unbiased but imprecise estimate of GFR at single time points. However, the accuracy of estimated GFR over time is not well known. Study Design: Longitudinal study of diagnostic test accuracy. Settings & Participants: 4 clinical trials with longitudinal measurements of GFR and serum creatinine on the same day, including individuals with and without kidney disease with a wide range of kidney function, diverse racial backgrounds, and varied clinical characteristics. Index Test: GFR estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Reference Test: GFR measured using urinary clearance of 125I-iothalamate. Results: Data included 19,735 GFR measurements in 3,531 participants during a mean follow-up of 2.6 years. Mean values at baseline for measured and estimated GFR and error (measured GFR - estimated GFR) were 73.1 (95% CI, 71.6 to 74.5), 72.7 (95% CI, 71.5 to 74.0), and 0.14 (95% CI, -0.35 to 0.63) mL/min/1.73 m 2, respectively. Mean rates of change in measured and estimated GFR and error were -2.3 (95% CI, -2.4 to -2.1), -2.2 (95% CI, -2.4 to -2.1), and -0.09 (95% CI, -0.24 to 0.05) mL/min/1.73 m 2 per year (P < 0.001, P < 0.001, and P = 0.2, respectively). Variability (ie, standard deviation) among participants in rate of change in measured GFR, estimated GFR, and error was 4.3, 3.4, and 3.3 mL/min/1.73 m 2 per year, respectively. Only 15% of participants had a rate of change in error >3 mL/min/1.73 m 2 per year, and only 2% had a rate of change in error >5% per year. Limitations: Participants' characteristics were not available over time. Conclusion: The accuracy of GFR estimates did not change over time. Clinicians should interpret changes in estimated GFR over time as reflecting changes in measured GFR rather than changes in errors in the GFR estimates in most individuals.
AB - Background: Change in glomerular filtration rate (GFR) is important for clinical decision making. GFR estimates from serum creatinine level provide an unbiased but imprecise estimate of GFR at single time points. However, the accuracy of estimated GFR over time is not well known. Study Design: Longitudinal study of diagnostic test accuracy. Settings & Participants: 4 clinical trials with longitudinal measurements of GFR and serum creatinine on the same day, including individuals with and without kidney disease with a wide range of kidney function, diverse racial backgrounds, and varied clinical characteristics. Index Test: GFR estimated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Reference Test: GFR measured using urinary clearance of 125I-iothalamate. Results: Data included 19,735 GFR measurements in 3,531 participants during a mean follow-up of 2.6 years. Mean values at baseline for measured and estimated GFR and error (measured GFR - estimated GFR) were 73.1 (95% CI, 71.6 to 74.5), 72.7 (95% CI, 71.5 to 74.0), and 0.14 (95% CI, -0.35 to 0.63) mL/min/1.73 m 2, respectively. Mean rates of change in measured and estimated GFR and error were -2.3 (95% CI, -2.4 to -2.1), -2.2 (95% CI, -2.4 to -2.1), and -0.09 (95% CI, -0.24 to 0.05) mL/min/1.73 m 2 per year (P < 0.001, P < 0.001, and P = 0.2, respectively). Variability (ie, standard deviation) among participants in rate of change in measured GFR, estimated GFR, and error was 4.3, 3.4, and 3.3 mL/min/1.73 m 2 per year, respectively. Only 15% of participants had a rate of change in error >3 mL/min/1.73 m 2 per year, and only 2% had a rate of change in error >5% per year. Limitations: Participants' characteristics were not available over time. Conclusion: The accuracy of GFR estimates did not change over time. Clinicians should interpret changes in estimated GFR over time as reflecting changes in measured GFR rather than changes in errors in the GFR estimates in most individuals.
KW - CKD-EPI estimating equation
KW - Glomerular filtration rate
KW - creatinine
KW - longitudinal measurements
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U2 - 10.1053/j.ajkd.2012.01.024
DO - 10.1053/j.ajkd.2012.01.024
M3 - Article
C2 - 22495467
AN - SCOPUS:84863981181
SN - 0272-6386
VL - 60
SP - 217
EP - 224
JO - American Journal of Kidney Diseases
JF - American Journal of Kidney Diseases
IS - 2
ER -
