Estimated Glomerular Filtration Rate: Fit for What Purpose?

Area of Science:

• Nephrology
• Epidemiology
• Biostatistics

Background:

• Chronic kidney disease (CKD) staging relies on estimated glomerular filtration rate (eGFR).
• Risk assessment models often use eGFR for prognosis, but its validity needs evaluation.
• Cockcroft-Gault equation (eCrCl) is an alternative method for estimating kidney function.

Purpose of the Study:

• To compare the prognostic performance of CKD staging based on eGFR versus eCrCl for 10-year all-cause mortality risk.
• To evaluate the validity of using eGFR in risk assessment models for long-term outcomes.

Main Methods:

• Multivariable-adjusted Cox regression analysis was employed.
• Hazard ratios for all-cause mortality were compared between CKD stages defined by eGFR and eCrCl.
• Discrimination analysis assessed model performance differences.

Main Results:

• Significant differences in mortality risk were found between CKD stages 3A and 3B-5 using eCrCl categories (p = 0.003), but not eGFR categories (p = 0.241).
• Discrimination analysis revealed a clinically significant improvement with eCrCl compared to eGFR in individuals aged ≤64 (relative integrated discrimination improvement 778.6%; p = 0.001).

Conclusions:

• While eGFR offers greater precision for single-point GFR estimation, eCrCl demonstrates superior performance in predicting long-term all-cause mortality risk.
• Current risk assessment models may benefit from reconsidering the use of eGFR for long-term prognostic evaluations in CKD patients.