Assessing glomerular filtration rate (GFR) in elderly Chinese patients with chronic kidney disease (CKD): A comparison of various predictive equations

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Abstract

The aim of this study was to evaluate the applicability of formulas based on serum creatinine (SC) levels in elderly Chinese patients with CKD. A total of 103 elderly CKD patients were investigated. The GFR was estimated with Cockcroft–Gault-equation, MDRD1-equation, abbreviated MDRD-equation, Jelliffe-1973-equation, Mawer-equation, Hull-equation, Jelliffe-1971-equation, SC-reciprocal-equation, Gate-equation and Bjornsson-equation. The accuracy of estimated GFR (eGFR) values was compared with the 99mTc-DTPA-GFR (standardized GFR = sGFR) in elderly CKD patients. Bland–Altman analysis demonstrated that Hull-equation, Cockcroft–Gault-equation and Bjornsson-equation were better than the other ones. However, the agreement limits of all the equations exceeded the prior acceptable tolerances defined as 60 ml/min/(1.73 m2). Linear regressions showed that the slopes of Jelliffe-1973-equation, Cockcroft–Gault-equation and Bjornsson-equation were closer to the identical line. The median of difference of MDRD1-equation, abbreviated MDRD-equation and Gate-equation were smaller. Accuracy of Jelliffe-1973-equation, Cockcroft–Gault-equation and Hull-equation were better than those of the other equations. But 30% accuracy of all the equations were less than 70%. When compared the bias as well as accuracy of eGFR with sGFR values in different stages of CKD, GFR estimated by MDRD1-equation, Hull-equation, Cockcroft–Gault-equation and Jelliffe-1973-equation showed good results. These results suggested that when SC was checked with enzymatic method, GFR-estimation equations may show great bias in elderly Chinese CKD patients. Further improved formulas are needed to evaluate renal function in elderly Chinese patients with CKD.

Introduction

The CKD has been identified as a public health problem. CKD is of high prevalence, it is harmful, costly, preventable and treatable. In almost every country, the proportion of people aged over 60 years is growing faster than any other age group (WHO, 2009), as a result of longer life expectancy. The number of elderly CKD cases increase, too (Brenner and Rector, 1999). The Cockcroft–Gault-equation, MDRD-equation, Jelliffe-1973-equation, Mawer-equation, Hull-equation, Jelliffe-1971-equation, SC-reciprocal-equation, Gate-equation and Bjornsson-equation are the most frequently used GFR prediction equations in the world (NKF, 2002). Most of the equations were derived predominantly from young or middle-aged subjects. Application of these GFR prediction equations to elderly CKD patients is limited, particularly in Chinese patients. On the austere challenge of CKD as well as the aging of the population, it is of great importance to analyze the applicability of formulas based on SC levels in elderly Chinese patients with CKD.

Section snippets

Participants

Patients with CKD diagnosed according to the NKF (2002) (>60 years of age) at the Division of Nephrology, Department of Internal Medicine, The Third Affiliated Hospital of Sun Yet-sun University, Guangzhou, China, were enrolled. Patients with acute kidney function-deterioration, clinical edema, skeletal muscle atrophy, pleural effusion or ascites, malnutrition, amputation, heart failure, or ketoacidosis were excluded from the study. Patients who were taking cimetidine or trimethoprim were

Clinical characteristics

Consecutive patients (n = 103) with CKD, including 25 males and 78 females, were enrolled. The average SC level of enrolled patients was 2.54 mg/dl (range 0.36–10.24). The average of sGFR measured by 99mTc-DTPA renal dynamic imaging method was 40.00 ml/min/(1.73 m2) (range 7.17–94.18). Causes of CKD and CKD stage classification are shown in Table 1. Patients were divided into five groups by 99mTc-DTPA renal dynamic imaging method according to the Kidney Disease Outcomes Quality Initiative (KDOQI) (

Discussion

By the end of 2005, elderly population in China aged 60 years and above was close to 144 million, accounting for 11% of the total population in China. Elderly population is growing at an average annual rate of about 3%. According to the generally acknowledged international standard, the age structure of Chinese population has entered the aging stage. The aging of the population increase austere challenges in China (State Council Information Office, 2006). The number of elderly CKD cases

Conclusions

This is the first study in elderly Chinese patients with CKD to evaluate the application of the most common used GFR-estimation-equations. Our data indicated when SC was checked with enzymatic method, the most frequently used GFR-estimation-equations are not sufficient for estimating GFR and radioisotope studies are still useful to evaluate renal function in elderly Chinese CKD patients. Further improved formulas are needed. At present, if conditions are not available, on the basis of both

Conflict of interest statement

None.

Acknowledgements

Thanks to Prof. M.H. Cheng in Department of Nuclear Medicine, The Third Affiliated Hospital of Sun Yet-sun University, Guangzhou, China, for his support. Thanks also to the patients for their good cooperation.

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