Chronic kidney disease in Taiwan

Abstract

In Chi Peng Wen and colleagues' paper on the mortality attributable to chronic kidney disease (CKD) in Taiwan,1Wen CP Cheng TYD Tsai MK et al.All-cause mortality attributable to chronic kidney disease: a prospective cohort study based on 462 293 adults in Taiwan.Lancet. 2008; 371: 2173-2182Summary Full Text Full Text PDF PubMed Scopus (699) Google Scholar the prevalence of CKD must be interpreted with caution. Wen and colleagues use a non-calibrated creatinine concentration to estimate glomerular filtration rate (GFR). Even if such non-calibration has little importance for mortality linked to CKD, it could have serious consequences on prevalence data.2Coresh J Eknoyan G Levey AS Estimating the prevalence of low glomerular filtration rate requires attention to the creatinine assay calibration.J Am Soc Nephrol. 2002; 13: 2811-2812Crossref PubMed Scopus (122) Google Scholar These prevalence data are thus not easy to compare with those of the US population, for which the newly expressed Modification of Diet in Renal Disease (MDRD) study equation3Levey AS Coresh J Greene T et al.Using standardized serum creatinine values in the Modification of Diet in Renal Disease study equation for estimating glomerular filtration rate.Ann Intern Med. 2006; 145: 247-254Crossref PubMed Scopus (3958) Google Scholar was used. This equation is applied to standardised creatinine with a factor of 175; Wen and colleagues used the version of the equation with a factor of 186. Moreover, the relation between creatinine and GFR varies with ethnic origin. For African-American3Levey AS Coresh J Greene T et al.Using standardized serum creatinine values in the Modification of Diet in Renal Disease study equation for estimating glomerular filtration rate.Ann Intern Med. 2006; 145: 247-254Crossref PubMed Scopus (3958) Google Scholar and Japanese4Imai E Horio M Nitta K et al.Modification of the Modification of Diet in Renal Disease (MDRD) Study equation for Japan.Am J Kidney Dis. 2007; 50: 927-937Summary Full Text Full Text PDF PubMed Scopus (301) Google Scholar populations, correction factors of 1·21 and 0·763, respectively, must be applied. Such a correction was not done by Wen and colleagues and should be discussed. Lastly, Wen and colleagues show that nearly one in three patients older than 65 years presented with stage 3 CKD. The term “disease” in this age group is debatable because the normal GFR in older populations is not well defined; a GFR of less than 60 mL/min/1·73 m2 could be regarded as physiological in a healthy older person.5Glassock RJ Winearls C An epidemic of chronic kidney disease: fact or fiction?.Nephrol Dial Transplant. 2008; 23: 1117-1121Crossref PubMed Scopus (173) Google Scholar We declare that we have no conflict of interest. Chronic kidney disease in Taiwan – Authors' replyRichard Glassock and colleagues ask whether reduced glomerular filtration rate (GFR) is a normal ageing process and whether our cohort could be skewed by including a larger number of older people in it. Older people were not over-represented in our cohort: 21·7% were aged 55 years or older versus 24·9% in the general population (corresponding figures for age 65 years or older 8·0% vs 13·4%). As shown in the table, those with stage 3a disease (GFR 45–59 mL/min/1·73 m2) had significantly increased mortality, including those with negative urine protein. Full-Text PDF