Prevalence estimates of chronic kidney disease in Canada: results of a nationally representative survey

Chronic kidney disease (CKD) is a global public health problem, affecting 10-16% of the adult population worldwide.1 CKD is characterised by low estimated glomerular filtration rate (eGFR) and high albuminuria,1 present for more than three months,1 and is associated with adverse outcomes, irrespective of hypertension and diabetes.2 Arora and colleagues shed new light on this question in this issue of CMAJ.3 They report that the overall prevalence of CKD was 12.5%; therefore the number of patients with CKD in Canada is estimated to be about 3 million. However, all the markers of CKD were obtained from single measurements; therefore the reported prevalence of CKD might be overestimated. Given the importance of excluding acute kidney disease (AKD, including AKI), it is recommended that any patient with a reduced GFR and no previous evidence of renal impairment should have a repeat eGFR within two weeks.4 For the diagnosis of microalbuminuria two abnormal results from three specimens are required.4

eGFR was calculated with an equation by Arora and colleagues developed by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. On the basis of the 2000 population of 201 million people older than 20 years in the USA, the CKD-EPI equation demonstrates the prevalence of 11.5% in CKD and yields a prevalence of CKD of 23.2 million.4 They used repeated measurements, obtained approximately 2 weeks after the original examination. Both CKD-EPI equation and the combination of cystatin C and serum creatinine equation are useful for CKD patients.5 However, the combination of cystatin C and serum creatinine equation does better.5 According to the new KDIGO clinical practice guideline for evaluation and management of CKD,1 we suggest measuring cystatin C in adults with creatinine-based eGFR 45-59 who do not have other markers of kidney damage if confirmation of CKD is required. If cystatin C-based eGFR is >60 mL/min/1.73 m2, the diagnosis of CKD is not confirmed. 2012 CKD-EPI creatinine-cystatin C equations were recommended.1,6

References 1. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int, Suppl. 2013; 3: 1-150. 2. Du X, Zhao Y, Huang W, et al. Association of chronic kidney disease with adverse outcomes. Lancet. 2013; 381(9866): 531-2. 3. Arora P, Vasa P, Brenner D, et al. Prevalence estimates of chronic kidney disease in Canada: results of a nationally representative survey. CMAJ. 2013 May 6. [Epub ahead of print] 4. Du X, Fan L. Prevalence of chronic kidney disease in China. Lancet. 2012; 380(9838): 213. 5. Du X, Liu L, Hu B, et al. Is the Chronic Kidney Disease Epidemiology Collaboration four-level race equation better than the cystatin C equation? Nephrology (Carlton). 2012,17(4):407-14. 6. Inker LA, Schmid CH, Tighiouart H, et al. Estimating glomerular filtration rate from serum creatinine and cystatin C. N Engl J Med. 2012;367:20-9.

Conflict of Interest:

None declared