CKD no impact on elderly mortality
Calculating eGFR is a 'waste of time' in the elderly because it suggests chronic kidney disease in patients who actually have no excess mortality risk.
A new study, carried out in a total population of more than 200,000 in Coventry, found that 41% of the over-75s tested had CKD at stages 3-5 but no increased risk of mortality.
The findings are fuelling the controversy that has greeted the use of eGFR since it was included in the quality and outcomes framework last year.
The study was based on laboratory results of 108,364 participants over 20 who had one or more serum creatinine measurements over a period of three years. The study included almost the entire population the city aged 65 and over.
The authors pointed out that quality indicators for CKD do not take into account increasing age, meaning that a glomerular filtration rate of 50ml/min/1.73m2 is regarded as indicative of moderate CKD (stage 3) whatever the age of the subject, even though this GFR falls well within the normal range in the elderly.
They said at older ages moderate to mild declines in renal function might confer little or no excess mortality risk.
Lead author Professor Neil Raymond, professor of epidemiology at the University of Warwick, said the findings called into question GPs' routine requests for serum creatinine levels, and called for more research on referral patterns.
Experts are now calling for a rethink of the use of eGFR scores in CKD diagnosis.
Professor David Fitzmaurice, professor of primary care at the University of Birmingham, said people who were essentially well were being labelled as having a disease.
'This is a waste of everybody's time. The nephrologists who introduced it did not anticipate the huge increase in referrals.' He said the implementation of eGFR had been mishandled and its validity as a screening tool had never been established. There was a need for a rethink of the whole process and the mechanism to change it 'may well be the QOF', he added.
But Dr Simon de Lusignan, an expert adviser on the QOF panel, said it would be premature to 'throw away the QOF' on the basis of one study.
Dr de Lusignan, senior lecturer in primary care at St George's, London, suggested that it could be made more sophisticated by adding in proteinuria tests as a way of further stratifying CKD risk.
The study was published online in Nephrology Dialysis Transplantation.CKD patients who do need referralCKD patients who do need referral CKD patients who do need referral
- Younger patients under 55
- Those with evidence of progressive kidney disease (with a change of more than 4ml/min/year)
- Those with protein:creatinine ratio above 100mg/mmol