Measured GFR confirms risk thresholds clinicians already rely on

Clinical Takeaway: eGFR remains a reliable tool for prognostication. Measured GFR offered little advantage over modern creatinine- and cystatin C–based estimates for predicting mortality, cardiovascular events, kidney failure, and hospitalization risk.

Current CKD staging and risk assessment rely largely on estimated GFR (eGFR). This study provides reassuring evidence that commonly used eGFR equations capture adverse outcome risk as well as directly measured GFR, supporting existing clinical thresholds and risk-based decision-making.

In one of the largest studies to directly compare measured and estimated kidney function, investigators analyzed 6,174 adults from Sweden who underwent iohexol-based measured GFR (mGFR) testing and had concurrent creatinine and cystatin C measurements. Participants were followed for major clinical outcomes including all-cause mortality, cardiovascular events, kidney failure, acute kidney injury, and hospitalization.

Across the full spectrum of kidney function, lower mGFR and lower eGFR were associated with progressively higher risks of adverse outcomes, with remarkably similar risk patterns regardless of whether kidney function was assessed by direct measurement or estimation. The findings suggest that the prognostic relationships underpinning current CKD definitions and staging are not substantially driven by non–GFR-related factors that can influence creatinine or cystatin C levels.

Among estimated measures, equations incorporating both creatinine and cystatin C generally tracked measured GFR most closely. The authors noted that “associations of adverse outcomes with mGFR and eGFR were largely similar,” supporting the continued use of eGFR-based thresholds in routine practice.

The results help address longstanding concerns that eGFR may misrepresent risk because creatinine and cystatin C are affected by factors beyond kidney function. Instead, the study suggests that modern eGFR equations provide a robust reflection of clinically meaningful risk while avoiding the cost and complexity of direct GFR measurement.

Source: Fu EL, et al. (2026, June 4). JAMA. Measured and Estimated Glomerular Filtration Rates and Risk of Adverse Health Outcomes