Is the Chronic Kidney Disease Epidemiology Collaboration creatinine–cystatin C equation useful for glomerular filtration rate estimation in the elderly?

Abstract

Background

We aimed to evaluate the performance of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine–cystatin C equation in a cohort of elderly Chinese participants.

Materials and methods

Glomerular filtration rate (GFR) was measured in 431 elderly Chinese participants by the technetium-99m diethylene-triamine-penta-acetic acid (^99mTc-DTPA) renal dynamic imaging method, and was calibrated equally to the dual plasma sample ^99mTc-DTPA-GFR. Performance of the CKD-EPI creatinine–cystatin C equation was compared with the Cockcroft–Gault equation, the re-expressed 4-variable Modification of Diet in Renal Disease (MDRD) equation, and the CKD-EPI creatinine equation.

Results

Although the bias of the CKD-EPI creatinine–cystatin C equation was greater than with the other equations (median difference, 5.7 mL/minute/1.73 m² versus a range from 0.4–2.5 mL/minute/1.73 m²; P<0.001 for all), the precision was improved with the CKD-EPI creatinine–cystatin C equation (interquartile range for the difference, 19.5 mL/minute/1.73 m² versus a range from 23.0–23.6 mL/minute/1.73 m²; P<0.001 for all comparisons), leading to slight improvement in accuracy (median absolute difference, 10.5 mL/minute/1.73 m² versus 12.2 and 11.4 mL/minute/1.73 m² for the Cockcroft–Gault equation and the re-expressed 4-variable MDRD equation, P=0.04 for both; 11.6 mL/minute/1.73 m² for the CKD-EPI creatinine equation, P=0.11), as the optimal scores of performance (6.0 versus a range from 1.0–2.0 for the other equations). Higher GFR category and diabetes were independent factors that negatively correlated with the accuracy of the CKD-EPI creatinine–cystatin C equation (β=−0.184 and −0.113, P<0.001 and P=0.02, respectively).

Conclusion

Compared with the creatinine-based equations, the CKD-EPI creatinine–cystatin C equation is more suitable for the elderly Chinese population. However, the cost-effectiveness of the CKD-EPI creatinine–cystatin C equation for clinical use should be considered.

Keywords:

• elderly
• equation
• glomerular filtration rate
• serum creatinine
• cystatin C

Acknowledgments

This work was supported by the National Natural Science Foundation of China (grant number 81370866 and number 81070612), the China Postdoctoral Science Foundation (grant number 201104335), the Guangdong Science and Technology Plan (grant number 2011B031800084), the Fundamental Research Funds for the Central Universities (grant number 11ykpy38), and the National Project of Scientific and Technical Supporting Programs Funded by the Ministry of Science and Technology of China (grant number 2011BAI10B00). This work was also supported in part by the National Natural Science Foundation of China (grant numbers 91029742, 81170647, and 81370837 to Hui Huang).

Disclosure

The authors report no conflicts of interest in this work.