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Switch to ‘more accurate’ CKD calculation urged

A switch to a ‘more accurate' equation to work out eGFR would reclassify the kidney function of a quarter of the general population, conclude researchers.

The study found the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) classified 7% fewer patients as having chronic kidney disease than the current guideline-recommended equation.

NICE guidance currently recommends the Modification of Diet in Renal Disease Study equation (MDRD) equation for estimating GFR, but this study found the CKD-EPI calculation was more accurate at predicting the risk of death or end-stage renal disease.

The DH's kidney tsar said the findings were in the scope of NICE's ongoing update of CKD diagnosis guidelines, although he warned the study did not include an assessment of adding in proteinuria on outcomes.

US researchers conducted a meta-analysis of 1.1 million patients from 45 different study cohorts, and calculated the risk of all-cause mortality, cardiovascular mortality and end-stage renal disease for different levels of eGFR.

In the general population, the CKD-EPI equation reclassified 24.4% of participants to a lower eGFR stage and 0.6% to a higher stage, compared with calculations with the MDRD equation.

Most reclassifications occurred in patients with CKD stages one to three, but in patients at high-risk of CKD or cardiovascular disease, 15.4% of high-risk cohorts were reclassified to a lower GFR stage and 1.2% were reclassified to a higher eGFR stage.

When just individuals diagnosed with CKD were looked at the reclassification rates were lower, with 6.6% moved to a lower stage, and 3.2% moved to a higher stage of disease with the CKD-EPI equation than with the MDRD equation.

Study lead Dr Josef Coresh, professor of epidemiology at the Welch Centre in Maryland, said: ‘Given more accurate GFR estimation, lower CKD prevalence estimates and better risk categorisation by the CKD-EPI equation without additional laboratory costs, its implementation for estimated GFR reporting could contribute to more efficient and targeted prevention and management of CKD-related outcomes.'

Dr Donal O'Donoghue, clinical director of renal medicine at Hope Hospital in Salford and national clinical director for kidney care at the Department of Health, said he was keen for the CKD-EPI equation to be looked at by NICE.

‘I'm pleased that NICE have it within the scope of their review for the CKD guideline.'

 ‘What's perhaps not apparent in the paper is the important role of proteinuria in both helping to confirm CKD when the eGFR, from whatever formula, is close to 60 and its role as an independent and amenable risk factor for CVD and progressive CKD.'


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