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CMAJ • November 11, 2003; 169 (10)
© 2003 Canadian Medical Association or its licensors

Letters
Correspondance

Nephrology care in Canada

Caroline Stigant*, Lesley Stevens* and Adeera Levin{dagger}

*Nephrology Research Fellows, Kidney Foundation of Canada, Vancouver, BC; {dagger}Professor of Medicine, University of British Columbia, Vancouver, BC

We agree with Keevin Bernstein and Claudio Rigatto that screening for chronic kidney disease should be restricted to high-risk populations, as stated in our article1 and in the Kidney Disease Outcome Quality Initiative (K/DOQI) guidelines.2 Screening in unselected populations is of limited value because of false-positive results and consequent need for further testing, as well as increased patient anxiety and decreased cost-effectiveness.

A number of initiatives to systematically evaluate screening and referral strategies are under way, including a randomized controlled trial planned for Canada. In the meantime, our educational article1 serves to deliver simple, practical recommendations and guidance before the conclusive results of these studies become available. To summarize information presented in our article,1 we would recommend referral to nephrologists when there are persistent (lasting more than 3 months) abnormalities: reduction in GFR to less than 30 mL/min (0.50 mL/s), microalbuminuria or unexplained reduction of GFR at any level. On the basis of these definitions, nephrology consultation could identify reversible causes of disease, but long-term follow-up might not be required. Thus, the referral recommendation is in keeping with current general medical practice principles. Bernstein and Rigatto suggest a reduced ability to retard disease progression at stage C in their system; however, accumulating data demonstrate that even at GFR levels between 15 and 30 mL/min (0.25 to 0.50 mL/s) some cardioprotective and renoprotective benefits can be achieved.3,4,5,6

In the K/DQOI staging system, stage 5 chronic kidney disease represents kidney failure, defined by GFR less than 15 mL/min (less than 0.25 mL/s) or by the need for dialysis. Neither the K/DQOI publication2 nor our article1 suggests that a GFR of less than 15 mL/min is an indication for dialysis per se. Thus, concern about an increase in resource utilization may well represent a misunderstanding of the staging system and clinical plan. As stated in our paper, we recommend adoption of Canadian Society of Nephrology guidelines regarding the timing of initiation of dialysis.7

There are many similarities between the scheme proposed by Bernstein and Rigatto and the K/DOQI staging system.2 The latter classification was formulated by a multidisciplinary team following an extensive literature review, has been published and thus widely disseminated, and has extensive associated materials for patients and allied health professionals. Although the classification may not be perfect, uniform terminology and concepts are important in communication with the general public, patients and clinicians for purposes of clinical care and research. In a recently published article,8 one of us has described the very controversies alluded to in Bernstein and Rigatto's letter, along with the advantages of adopting the approach espoused in our CMAJ article.1

Given that kidney disease is a major predictor of outcome in all populations studied (i.e., patients with various coexisting illnesses), the need for accurate assessment with an evidence-based classification system (accompanied by associated action plans) outweighs the issue of potential misclassification, which in most cases will be transient. Failure to agree upon and use a common, if flawed, terminology, could retard our ability to pursue important clinical questions and improve patient care.

Caroline Stigant Lesley Stevens Nephrology Research Fellows Kidney Foundation of Canada Adeera Levin Professor of Medicine University of British Columbia Vancouver, BC

References

  1. Stigant C, Stevens L, Levin A. Nephrology: 4. Strategies for the care of adults with chronic kidney disease. CMAJ 2003;168(12):1553-60.[Free Full Text]
  2. National Kidney Foundation (NKF) Kidney Disease Outcome Quality Initiative (K/DOQI) Advisory Board. K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Kidney Disease Outcome Quality Initiative. Am J Kidney Dis 2002; 39(2 Suppl 2):S1-246.
  3. Brenner BM, Cooper ME, de Zeeuw D, Keane WF, Mitch WE, Parving HH, et al. Effects of losartan on renal and cardiovascular outcomes in patients with type 2 diabetes and nephropathy. N Engl J Med 2001;345(12):861-9.[Abstract/Free Full Text]
  4. Parving HH, Lehnert H, Brochner-Mortensen J, Gomis R, Andersen S, Arner P. The effect of irbesartan on the development of diabetic nephropathy in patients with type 2 diabetes. N Engl J Med 2001;345(12):870-8.[Abstract/Free Full Text]
  5. Mann JF, Gerstein HC, Yi QL, Lonn EM, Hoogwerf BJ, Rashkow A, et al. Development of renal disease in people at high cardiovascular risk: results of the HOPE randomized study. J Am Soc Nephrol 2003;14(3):641-7.[Abstract/Free Full Text]
  6. Yusuf S, Sleight P, Pogue J, Bosch J, Davies R, Dagenais G. Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients. The Heart Outcomes Prevention Evaluation Study Investigators. N Engl J Med 2000;342(3):145-53.[Abstract/Free Full Text]
  7. Churchill DN, Blake PG, Jindal KK, Toffelmire EB, Goldstein MB. Clinical practice guidelines for initiation of dialysis. Canadian Society of Nephrology. J Am Soc Nephrol 1999;10(Suppl 13): S289-91.
  8. Levin A. The advantage of a uniform terminology and staging system for chronic kidney disease (CKD). Nephrol Dial Transplant 2003; 18 (8): 1446-51.[Free Full Text]




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