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Kidney Week

Abstract: PO0549

Clinical Impact of Body Muscle Mass for Kidney Function Evaluation: New eGFR Formula Based on Serum Creatinine and Body Muscle Mass

Session Information

Category: CKD (Non-Dialysis)

  • 2102 CKD (Non-Dialysis): Clinical, Outcomes, and Trials

Authors

  • Goto, Kazunori, Nagoya University, Nagoya, Aichi, Japan
  • Yasuda, Yoshinari, Nagoya University, Nagoya, Aichi, Japan
  • Kato, Sawako, Nagoya University, Nagoya, Aichi, Japan
  • Maruyama, Shoichi, Nagoya University, Nagoya, Aichi, Japan
Background

Kidney function is globally evaluated by estimated glomerular filtration ratio (eGFR) based on serum creatinine (Cre). Since Cre is influenced by body muscle mass, there is serious concern of overestimation of eGFR among elderly people with less muscle volume due to frailty. In this study, eGFR based on Cre (eGFRcreat) and CysC (eGFRcys) were analyzed in association with psoas muscle mass index (PMI) by CT image among CKD patients whose kidney function was accurately evaluated by measured GFR (mGFR) computed from inulin clearance (Cin).

Methods

Study design was single-center cross-sectional retrospective study. Study subjects were consecutive 184 CKD patients (123 males) at Nagoya university hospital whose Cin and abdominal CT were examined within 1 year between 2009 and 2013. New eGFR formula based on Cre and PMI (eGFRcreat-PMI) were developed in 122 patients and validated in 62 patients, which were randomly determined to each cohort. 20% accuracy for Cin was analyzed by eGFRcreat and eGFRcys calculated by eGFR formulae for Japanese. The performance of eGFRcreat-PMI was assessed by means of bias (eGFR-mGFR), accuracy (percentage of estimates within 20% of mGFR), root mean squared error, and correlation coefficient. In PMI tertile subgroups and GFR(Cin) subgroups (<30, 30-60, 60<), the performance of each formulae was assessed.

Results

Patients’ characteristics (n=184, mean(SD) or median[IQR]) were age: 62 [50, 70], eGFRcreat: 58.5 (25.5), eGFRcys: 59.4 (25.9), Cin: 55.0 (25.0) and PMI: 7.29 [6.18, 9.11]. Log-PMI was significantly associated with age, gender, log-BMI, log-Cre and uCre in univariate analyses, and with age, gender and log-BMI in multivariate analysis. New GFR formula (eGFRcreat-PMI) was well correlated with Cin. 20% accuracies for Cin was the highest in eGFRcreat-PMI (74.5%), compared to eGFRcys (67.9%) and eGFRcreat (68.5%), which was more prominent among low PMI tertile group (77.4% in eGFRcreat-PMI, 67.7% in eGFRcys, and 71.0% in eGFRcreat) and high PMI tertile group (73.8% in eGFRcreat-PMI, 59.0% in eGFRcys, and 60.7% in eGFRcreat).

Conclusion

Body muscle mass seriously influences accuracy of kidney function evaluation, and new GFR formula based on PMI and Cre would be useful for accurate evaluation of kidney function, especially among patients with low and high body muscle mass.