GFR estimation: from physiology to public health

Area of Science:

• Nephrology
• Clinical Chemistry
• Epidemiology
• Biostatistics

Background:

• Estimating glomerular filtration rate (eGFR) is vital for clinical practice, research, and public health.
• Accurate eGFR interpretation relies on understanding the underlying physiological, laboratory, epidemiological, and biostatistical principles.
• Equations developed in diverse populations are preferred for general use due to reduced bias at higher GFRs.

Purpose of the Study:

• To evaluate the accuracy and applicability of various GFR estimating equations.
• To compare the performance of CKD-EPI equations with the MDRD Study equation.
• To identify the most suitable equations for routine clinical reporting and confirmatory testing.

Main Methods:

• Review and analysis of GFR estimating equations, focusing on those developed in diverse populations.
• Comparison of equations based on single versus multiple filtration markers.
• Evaluation of the CKD-EPI creatinine, CKD-EPI cystatin C, and CKD-EPI creatinine-cystatin C equations.

Main Results:

• CKD-EPI equations are the most accurate GFR estimating equations evaluated in large, diverse populations.
• The 2009 CKD-EPI creatinine equation is more accurate than the 2006 MDRD Study equation and recommended for routine reporting.
• The 2012 CKD-EPI cystatin C equation offers similar accuracy without race specification, while the combined creatinine-cystatin C equation is most accurate for confirmatory testing.

Conclusions:

• The CKD-EPI equations, particularly the 2009 creatinine-based equation, should replace the MDRD equation for routine eGFR reporting.
• The 2012 CKD-EPI cystatin C and creatinine-cystatin C equations provide valuable alternatives and confirmatory tools.
• Future improvements necessitate development in more representative populations using multiple markers and advanced statistical evaluation.