Applicability of estimated glomerular filtration rate in stratifying chronic kidney disease

Abstract

Objective. The aim of this audit was to evaluate the degree of glomerular filtration rate (GFR) among inpatients and outpatients in a District General Hospital, with special attention given to laboratory testing and impact on health delivery. Background. UK Chronic Kidney Disease guidelines recommend that investigation of renal function should be accompanied by an estimation of GFR (eGFR) in order to identify and manage patients with chronic kidney disease (CKD). The estimated GFR forms the basis for classification of CKD and appropriate action plans for patient management and follow‐up. Method. A retrospective audit of 8160 results from a predominantly British Caucasian population was carried out; extracting creatinine results from two isolated months in years 2001 and 2004. The estimated GFR (eGFR) was calculated using the MDRD formula. The data were classified according to demography, serum creatinine and eGFR. Patients from the 2001 database were classified according to eGFR and those with a value of <60 mL/min/1.73m² were followed up in 2004. Results. The difference in eGFR between the men and women was significantly different with medians (confidence intervals) of 80.1 (41–109) and 64.4 (30–84.6) (p<0.0001), respectively. There was an inverse association between age and eGFR in both genders (p<0.0001), with a decrease in eGFR of around 7 % for each decade increase in age. 1926 patients (24 %) of results studied had eGFR <60 mL/min, of whom 64 % were females and 36 % males. Follow‐up of patients with eGFR<60 mL/min from 2001 showed that 4 % progressed to stages 4 and 5 CKD. Conclusion. eGFR is inversely associated with increasing age and female gender. MDRD derived eGFR fails to completely compensate for age and gender variations and thus different action limits may be required. Small but significant numbers of patients progressed to stages 4 and 5 CKD. Additional clarity in describing “progressive fall in eGFR” in the guidelines would improve identification of the population most at risk.

• Chronic kidney disease
• estimated glomerular filtration rate
• renal function