Intended for healthcare professionals

Education And Debate

Classifying kidney problems: can we avoid framing risks as diseases?

BMJ 2004; 329 doi: (Published 14 October 2004) Cite this as: BMJ 2004;329:912
  1. Catherine M Clase (, associate professor1,
  2. Amit X Garg, assistant professor2,
  3. Bryce A Kiberd, professor3
  1. 1 Department of Medicine, McMaster University, Hamilton, Ontario, Canada
  2. 2 Department of Medicine, University of Western Ontario, London, Ontario, Canada
  3. 3 Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
  1. Correspondence to: C M Clase, Suite 708, 25 Charlton Ave East Hamilton, Ontario L8N 1Y2, Canada
  • Accepted 28 June 2004

A new international classification system for kidney problems is currently being developed. How can it meet the challenges of avoiding labelling all patients with low function as having kidney disease and being usable in countries with limited resources?


Patients with low kidney function may eventually need dialysis or transplantation and can die if these treatments are declined or not available. Early intervention is required to prevent these severe outcomes. Interventions that reduce the rate of loss of kidney function have been shown to be effective in selected patient groups. However, mild to moderate low kidney function is prevalent and often unrecognised in the general population, particularly in elderly people. An internationally accepted classification scheme for kidney problems is needed to facilitate research, clinical management, and the development of health policy.

Importance of kidney disease

End stage renal disease, defined as kidney function so low that dialysis or transplantation is needed, currently affects 404-1022 people per million population in Europe.1 The burden is large for both patients, whose quality of life and life expectancy are impaired,2 and society because of the high cost of renal replacement therapy.3

Low kidney function refers to abnormalities in clearance of uraemic toxins, often assessed as creatinine clearance or glomerular filtration rate. Low clearance, or low glomerular filtration rate, is commonly known as chronic renal failure. The term chronic renal insufficiency is also widely used; it may have been coined to reduce the apparent severity of this diagnosis. A standard definition does not exist for either term.4

Our understanding of the progression of low glomerular filtration rate derives from observational studies and randomised trials conducted in patients referred for specialist care; these have shown falls in glomerular filtration rate of about 7 to 8 ml/min.5 Until recently it was assumed that all patients with low …

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