TOPLINE:

In a primary care cohort, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation vs the Modification of Diet in Renal Disease (MDRD) equation classified 7.73% vs 6.57% of individuals as having CKD stages G3-G5. Classification differences were most pronounced in advanced stages and among older adults.

METHODOLOGY:

• Researchers conducted a cross-sectional analysis of electronic health records from 117,055 adults (42.47% men) across 14 primary care units and Pedro Hispano Hospital in Portugal (2000-2022) to assess how two equations differ in estimated glomerular filtration rate (eGFR)-based CKD stage classification.
• They performed serum creatinine concentration measurements using standardised methods, with the most recent value for each individual used to calculate the eGFR and determine CKD stage classification focusing on stages G3-G5.
• The analysis compared eGFR-based CKD stage classification between CKD-EPI and MDRD equations, calculating absolute and relative differences.
• CKD staging followed Kidney Disease: Improving Global Outcomes guidelines, with no confirmation of chronicity, so the classification reflected eGFR-based CKD staging rather than confirmed chronic disease.
• The analysis compared CKD-EPI and MDRD equations overall and by age over a decade, BMI categories, and comorbidities such as heart failure, diabetes, and hypertension.

TAKEAWAY:

• Overall eGFR-based CKD staging varied: The CKD-EPI vs the MDRD equation classified 7.73% vs 6.57% of individuals as having CKD stages G3-G5, with relative increases most pronounced in advanced stages: G3b, +29.4%; G4, +23.6%; and G5, +34.4%.
• Among individuals older than 50 years, the CKD-EPI equation consistently resulted in a higher proportion of individuals being classified into CKD stages than the MDRD equation across all stages.
• Across all BMI categories, the CKD-EPI equation consistently classified a higher proportion of individuals into CKD stages than the MDRD equation, with differences observed in those with underweight, normal weight, overweight, and obesity; relative increases were most pronounced in stage G5.
• Comorbidity subgroups, such as those with heart failure, showed higher CKD stage classification with the CKD-EPI equation.

IN PRACTICE:

"The differential behavior of estimating equations according to population characteristics highlights the role of CKD-EPI primarily as a classification and risk stratification tool, rather than as a definitive diagnostic instrument," the authors wrote.

SOURCE:

This study was led by Nuno Capela, Family Health Unit, Unidade de Saúde Familiar Serpa Pinto, Porto, Portugal. It was published online on March 07, 2026, in the Journal of Clinical Medicine.

LIMITATIONS:

The quality and completeness of clinical records may have affected the interpretation of the results. The absence of data on the urinary albumin-to-creatinine ratio in a substantial proportion of individuals limited the comprehensive assessment of kidney risk and restricted albuminuria-stratified analyses. The classification of CKD stages relied on a single most recent creatinine value, without confirmation of persistence for at least 3 months.

DISCLOSURES:

This study did not receive any external funding. The authors declared having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.