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Abstract: PO1209

Temporal Change in Formula-Derived Creatinine Index as a Surrogate for Lean Muscle Mass Correlates Well with Change in Post-Hemodialysis Weight but Not with the Volume of Urea Distribution

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Ling, Xiao, University of California Davis, Sacramento, California, United States
  • Chin, Andrew I., University of California Davis, Sacramento, California, United States
Background

In hemodialysis (HD) patients, creatinine kinetic modeling to derive a Creatinine Index (CI) is a measure of lean muscle mass. Loss of lean muscle mass is associated with poor outcomes. This modeling process is complex and not routinely performed. A simplified formula for CI was developed in a previous study. We sought to determine if temporal change in the calculated CI using the simplified formula correlated with more commonly available data used in routine clinical care of HD patients.

Methods

We retrospectively queried long-term HD patients without residual function who had available serologic, urea kinetic, and clinical care data at least 18 months over a 24 month span. We used the simplified formula previously published for creatinine index: CI (mg/kg/day) = 16.21 + 1.12 x [1 if male, 0 if female ] - 0.06 x age (yrs) – 0.08 x spKt/Vurea + 0.009 x Creat (pre-dialysis). Regression lines were created for each parameter over the 24 months. Slopes in the change of CI, post-HD wt, urea generation rate (G) and kinetic modeled distribution of urea (V) were compared by paired t-tests.

Results

We included 455 long-term HD patients without residual renal function (we measure this routinely) with at least 18 out of 24 months of complete data. Mean HD vintage was 40 months. We found the slope of CI to be poorly correlated to V or G, but did compare favorably to change over time slopes for V and post-HD weight.

Conclusion

In this retrospective analysis in HD patients, the temporal change of calculated Creatinine Index as an indicator of lean muscle mass compared best with change in post-HD weight. While the volume of urea distribution is related to body composition, the change V over time surprisingly did not mirror that of calculated CI. We also compared the slope of V to that of post-HD weight and found a strong association. The simplified equation for CI, applied to our population in Northern California, may correlate poorly with lean muscle mass.

Comparisons of slope of regression lines for stated factors
 P-value of pair-wise t-test
Creatinine index (CI) to urea generation rate (G)0.99
CI to urea distribution volume (V)0.69
CI to post-HD weight0.0005
V to post-HD weight0.001

Funding

  • Clinical Revenue Support