eGFR ‘powerful’ operative risk gauge

By Eleanor McDermid, Senior medwireNews Reporter

Patients' estimated glomerular filtration rate (eGFR) is highly predictive of their risk for dying after surgery, shows a systematic review and meta-analysis.

"The weight of the evidence, as summarized in this important meta-analysis, suggests that the time has come to move beyond discrete creatinine measurement for risk assessment," say John Augoustides and colleagues from the University of Pennsylvania in Philadelphia, USA, in an editorial accompanying the study in Anesthesiology.

But they stress that more research is needed to determine the predictive power of eGFR in noncardiovascular surgery; of the 46 studies in the analysis, 28 were purely about cardiac surgery, 16 covered vascular surgery, and just two focused on other types of surgery.

In the pooled analysis, patients with an eGFR below 60 mL/min per 1.73 m² had a 2.98-fold increased risk for death within 30 days of surgery and a 3.13-fold increase risk for developing acute kidney injury, relative to those with higher eGFRs.

A reduced eGFR also predicted all-cause mortality and major adverse cardiovascular events over the longer term, report John Mooney (The George Institute for Global Health, Sydney, Australia) and co-workers.

Mortality risk within 30 days rose with the severity of kidney disease, with eGFRs of 60, 30, and 15 mL/min per 1.73 m² (ie, mild, moderate, and severe disease) associated with risk increases of 2.04-, 4.17-, and 6.00-fold, respectively, compared with an eGFR of at least 90 mL/min per 1.73 m².

The researchers note that the association between disease severity and postoperative mortality risk was nonlinear, but assuming a linear increase revealed a 27% rise in mortality risk per 10 mL/min per 1.73 m² reduction in eGFR.

"This is a powerful concept, as it means that even subclinical increases in creatinine significantly elevate perioperative risk," say Augoustides et al. "Given the powerful evidence provided by this study and the clinical convenience of eGFR calculators, perioperative clinicians should strive to recognize these patients before surgery."

The editorialists believe that measuring eGFR gives "insights on perioperative risk beyond those that could be gleaned from traditional definitions of renal dysfunction that employ simple cut-off values for preoperative creatinine."

They say: "It follows that eGFR should be tested, validated, and potentially included in contemporary approaches to perioperative risk stratification."

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