Chronic kidney disease: a large-scale population-based study of the effects of introducing the CKD-EPI formula for eGFR reporting

OBJECTIVE: 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. DESIGN: Retrospective study of all creatinine measurements and calculation of eGFRs using Modification of Diet in Renal Disease (MDRD) and CKD-EPI formulae. SETTING: General population, Oxfordshire, UK. PARTICIPANTS: An unselected population of around 660 000. INTERVENTIONS: 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). RESULTS: 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. CONCLUSIONS: 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.