Reporting eGFR has benefits

Giles and Fitzmaurice overlooked one of the main aims of the recent guidelines on chronic kidney disease and did not take into account the accepted definition of stages 1 and 2, or the recommendations on screening.^{1 2} Reducing late referral of people who are heading towards dialysis (and avoiding the associated poor outcome) was one of the intentions of the guidelines.²

The main reason for late referral is that glomerular filtration rate (GFR) can be very low when the serum creatinine is only modestly increased and the severity of the kidney disorder is underestimated. In spite of its shortcomings, eGFR reporting is the best method available to aid interpretation of serum creatinine. Since this was introduced in our unit (together with a programme of education in primary care), the proportion of new patients receiving dialysis who were referred late (defined as within 90 days) has fallen from 38% to 25% (P<0.01).

The diagnosis of stages 1 and 2 does not depend on GFR alone. Stages 1 and 2 refer to people known to have another kidney problem—either functional (proteinuria) or structural (polycystic disease)—and in whom the GFR is at least 60 ml/min (normal or nearly so).

The guidelines did not advocate a screening programme but recommended testing for kidney disease in those at risk, including patients with diabetes and hypertension in whom such testing has been normal practice for several years. The suggested improvements in sample collection and analysis deserve attention in their own right, irrespective of policies on eGFR reporting.