Giles and Fitzmaurice's arguments are designed to persuade BMJ readers that reporting estimated glomerular filtration rate (eGFR) has introduced a screening programme by the back door, will pressurise specialist services, and cause unnecessary anxiety and harm to patients in terms of getting life insurance and receiving inappropriate treatment.1
The marked increase in referrals of patients with newly diagnosed chronic kidney disease is likely to be temporary due to referral of patients with prevalent disease. UK guidelines ensure that only patients who will receive added value from a specialist opinion are referred2: most can safely and more efficiently be managed in primary care.3 Most patients diagnosed as having chronic kidney disease as a result of eGFR reporting are older, few of whom will take out new life insurance. Angiotensin converting enzyme inhibitors are indicated only in the presence of hypertension (in the quality and outcomes framework (QOF)), in keeping with current NICE guidance.
Reporting eGFR has improved the clinical interpretation of an established test (serum creatinine).4 An important aim was to reduce the morbidity and mortality associated with late referral to nephrology services of patients with advanced disease.5 The indications for testing serum creatinine concentration have not been changed by eGFR reporting.
The simplified MDRD (modification of diet in renal disease) equation does not provide a perfect estimate of glomerular filtration rate. Improved assay precision, specificity, and standardisation will help. Currently, harmonisation through the United Kingdom National External Quality Assessment Scheme achieves between-laboratory agreement (coefficient of variation) of around 6% at rates around 60 ml/min/1.73 m2. As the authors acknowledge, the equation is useful to identify stage 3-5 disease, as required by the QOF.
Competing interests: None declared.
References
- 1.Giles PD, Fitzmaurice DA. Formula estimation of glomerular filtration rate: have we gone wrong? BMJ 2007;334:1198-200. (9 June.) [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Joint Specialty Committee on Renal Medicine of the Royal College of Physicians and the Renal Association, and the Royal College of General Practitioners. Chronic kidney disease in adults: UK guidelines for identification, management and referral London: Royal College of Physicians, 2006 [DOI] [PubMed]
- 3.Mitra PK, Tasker PR, Ell MS. Chronic kidney disease. BMJ 2007;334:1273 (16 June.) [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Wyatt C, Konduri V, Eng J, Rohatgi R. Reporting of estimated GFR in the primary care clinic. Am J Kidney Dis 2007;49:634-41. [DOI] [PubMed] [Google Scholar]
- 5.Roderick P, Jones C, Tomson C, Mason J. Late referral for dialysis: improving the management of chronic renal disease. Q J Med 2002;95:363-70. [DOI] [PubMed] [Google Scholar]