To evaluate the effects of introducing the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) formula for estimated glomerular filtration rate (eGFR) reporting in the adult population in routine clinical practice with clinician-directed testing.
Retrospective study of all creatinine measurements and calculation of eGFRs using Modification of Diet in Renal Disease (MDRD) and CKD-EPI formulae.
General population, Oxfordshire, UK.
An unselected population of around 660 000.
Reporting of eGFRs using MDRD or CKD-EPI formulae.
Primary and secondary outcome measures
Evaluation of the effects of the CKD-EPI formula on the prevalence of different stages of chronic kidney disease (CKD).
The CKD-EPI formula reduced the prevalence of CKD (stages 2–5) by 16.4% in patients tested in primary care. At the important stage 2–stage 3 cut-off, there was a relative reduction of 7.5% in the prevalence of CKD stages 3–5 from 15.7% to 14.5%. The CKD-EPI formula reduced the prevalence of CKD stages 3–5 in those aged <70 but increased it at ages >70. Above 70 years, the prevalence of stages 3–5 was similar with both equations for women (around 41.2%) but rose in men from 33.3% to 35.5%. CKD stages 4–5 rose by 15% due exclusively to increases in the over 70s, which could increase specialist referral rates. The CKD classification of 18.3% of all individuals who had a creatinine measurement was altered by a change from the MDRD to the CKD-EPI formula. In the UK population, the classification of up to 3 million patients could be altered, the prevalence of CKD could be reduced by up to 1.9 million and the prevalence of CKD stages 3–5 could fall by around 200 000.
Introduction of the CKD-EPI formula for eGFR reporting will reduce the prevalence of CKD in a primary care setting with current testing practice but will raise the prevalence in the over 70s age group. This has implications for clinical practice, healthcare policy and current prevalence-based funding arrangements.
Estimated glomerular filtration rates form the basis for clinical and health policy decisions in chronic kidney disease.
The new CKD-EPI formula for estimated glomerular filtration rates estimates renal function better than the Modification of Diet in Renal Disease formula in current use.
We have studied the effects of using the CKD-EPI formula in a UK population of over half a million.
Overall, the CKD-EPI formula produces higher better estimated glomerular filtration rates, which reduces the diagnosis of chronic kidney disease. However, in men older than 70 years, it produces lower worse estimated glomerular filtration rates and increases the number with chronic kidney disease stages 3–5.
Our results predict a net reduction of around 200 000 in the numbers with chronic kidney disease stages 3–5 in the UK. This would reduce the primary care chronic kidney disease registers, inappropriate disease labelling and patient monitoring.
The chronic kidney disease classification of up to 3 million patients could be altered by the use of the CKD-EPI formula in the UK.
Strengths and limitations of this study
The study is large and unbiased. All primary care samples taken during the study period were analysed, so the results represent current clinical testing practice.
Estimated glomerular filtration rates are sufficient to diagnose chronic kidney disease stages 3–5, but stages 1–2 also require proteinuria or a structural abnormality, which cannot be assessed in this study. However, a change in estimated glomerular filtration rate can still alter the classification of stage 1 or 2.