Accuracy of a GFR estimating equation over time in people with a wide range of kidney function

Smita Padala, Hocine Tighiouart, Lesley A. Inker, Gabriel Contreras, Gerald J. Beck, Julia Lewis, Michael W Steffes, Roger A. Rodby, Christopher H. Schmid, Andrew S. Levey

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

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.

Original languageEnglish (US)
Pages (from-to)217-224
Number of pages8
JournalAmerican Journal of Kidney Diseases
Volume60
Issue number2
DOIs
StatePublished - Aug 1 2012

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Glomerular Filtration Rate
Kidney
Creatinine
Iothalamic Acid
Kidney Diseases
Serum
Chronic Renal Insufficiency
Routine Diagnostic Tests
Longitudinal Studies
Epidemiology

Keywords

  • CKD-EPI estimating equation
  • Glomerular filtration rate
  • creatinine
  • longitudinal measurements

Cite this

Padala, S., Tighiouart, H., Inker, L. A., Contreras, G., Beck, G. J., Lewis, J., ... Levey, A. S. (2012). Accuracy of a GFR estimating equation over time in people with a wide range of kidney function. American Journal of Kidney Diseases, 60(2), 217-224. https://doi.org/10.1053/j.ajkd.2012.01.024

Accuracy of a GFR estimating equation over time in people with a wide range of kidney function. / Padala, Smita; Tighiouart, Hocine; Inker, Lesley A.; Contreras, Gabriel; Beck, Gerald J.; Lewis, Julia; Steffes, Michael W; Rodby, Roger A.; Schmid, Christopher H.; Levey, Andrew S.

In: American Journal of Kidney Diseases, Vol. 60, No. 2, 01.08.2012, p. 217-224.

Research output: Contribution to journalArticle

Padala, S, Tighiouart, H, Inker, LA, Contreras, G, Beck, GJ, Lewis, J, Steffes, MW, Rodby, RA, Schmid, CH & Levey, AS 2012, 'Accuracy of a GFR estimating equation over time in people with a wide range of kidney function', American Journal of Kidney Diseases, vol. 60, no. 2, pp. 217-224. https://doi.org/10.1053/j.ajkd.2012.01.024
Padala, Smita ; Tighiouart, Hocine ; Inker, Lesley A. ; Contreras, Gabriel ; Beck, Gerald J. ; Lewis, Julia ; Steffes, Michael W ; Rodby, Roger A. ; Schmid, Christopher H. ; Levey, Andrew S. / Accuracy of a GFR estimating equation over time in people with a wide range of kidney function. In: American Journal of Kidney Diseases. 2012 ; Vol. 60, No. 2. pp. 217-224.
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abstract = "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.",
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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 W

AU - Rodby, Roger A.

AU - Schmid, Christopher H.

AU - Levey, Andrew S.

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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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