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Abstract: PO2331

Muscle Mass and Estimates of Renal Function: A Longitudinal Cohort Study

Session Information

Category: CKD (Non-Dialysis)

  • 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

  • Groothof, Dion, Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Post, Adrian, Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Polinder-Bos, Harmke A., Erasmus MC, Rotterdam, Zuid-Holland, Netherlands
  • Erler, Nicole, Erasmus MC, Rotterdam, Zuid-Holland, Netherlands
  • Flores-Guerrero, Jose L., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Kootstra-Ros, Jenny E., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Pol, Robert, Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • De Borst, Martin H., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Gansevoort, Ron T., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Gans, Reinold O.B., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Kremer, Daan, Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Kieneker, Lyanne M., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
  • Bano, Arjola, Universitat Bern Institut fur Sozial- und Praventivmedizin, Bern, BE, Switzerland
  • Muka, Taulant, Universitat Bern Institut fur Sozial- und Praventivmedizin, Bern, BE, Switzerland
  • Franco, Oscar, Universitat Bern Institut fur Sozial- und Praventivmedizin, Bern, BE, Switzerland
  • Bakker, Stephan J.L., Universitair Medisch Centrum Groningen, Groningen, Groningen, Netherlands
Background

Current guidelines suggest using creatinine-based estimated glomerular filtration rate (eGFRCr) as measurement of renal function, but muscle mass as key determinant of creatinine after renal function may lead to imprecise estimates. We explored effects of 24-hour height-indexed creatinine excretion rate (CER index) – as accurate marker of muscle mass – on eGFRCr and muscle mass-independent cystatin C-based eGFR (eGFRCys) and predicted probabilities of misclassification given age, sex, and CER index.

Methods

We included 8,076 community-dwelling individuals enrolled in the PREVEND study. Misclassification was defined as eGFRCr ≥60 ml/min/1.73 m2 when eGFRCys was <60 ml/min/1.73 m2. Cross-sectional associations were quantified with quantile regression and logistic regression and longitudinal associations with linear mixed-effects models.

Results

In a simulated 70-year-old male with low muscle mass (CER index of 4 mmol/24 hour/m), predicted baseline eGFRCr and eGFRCys were 87.5 and 60.5 (difference: 27.0) ml/min/1.73 m2, respectively (Figure). Percentages (95% CI) of misclassification in males and females older than 60 years with low muscle mass were 18.5% (14.8% to 22.1%) and 15.2% (11.6% to 18.8%), respectively. Over time, for that same 70-year-old male, eGFRCr and eGFRCys disagreed with 2.3, 4.9, 7.7, and 10.7 ml/min/1.73 m2 at baseline, 5 years, 10 years, and 15 years of follow-up, respectively.

Conclusion

Low muscle mass may cause considerable overestimation of single measurements of eGFRCr. Muscle wasting may cause spurious overestimation of repeatedly measured eGFRCr. Implementing muscle mass-independent markers for estimating renal function, like cystatin C as superior alternative to creatinine, is crucial to accurately assess renal function in settings of low muscle mass or muscle wasting.