Kidney Week

Abstract: FR-PO217

CT-Defined Sarcopenia and Performance of GFR-Estimating Equations in Patients with Cancer

Session Information

• Onconephrology: Immunotherapy Nephrotoxicity and Assessment of GFR
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Onconephrology

• 1700 Onconephrology

Authors

• Costa e Silva, Veronica Torres, University of São Paulo, São Paulo, São Paulo, Brazil

Veronica Torres Costa e Silva, MD

• Sise, Meghan E., Massachusetts General Hospital, Boston, Massachusetts, United States

Meghan E. Sise, MD, MS

• Inker, Lesley Ann, Tufts Medical Center, Boston, Massachusetts, United States

Lesley Ann Inker, MD, MS

• Strufaldi, Fernando Louzada, University of São Paulo, São Paulo, São Paulo, Brazil

Fernando Louzada Strufaldi, MD

• Mantz, Lea, Massachusetts General Hospital, Boston, Massachusetts, United States

Lea Mantz

• Ouyang, Tianqi, Massachusetts General Hospital, Boston, Massachusetts, United States

Tianqi Ouyang, MPH

• Caires, Renato A., University of São Paulo, São Paulo, São Paulo, Brazil

Renato A. Caires, MD

• Sapienza, Marcelo Tatit, University of São Paulo, São Paulo, São Paulo, Brazil

Marcelo Tatit Sapienza, MD, PhD

• Burdmann, Emmanuel A., University of São Paulo, São Paulo, São Paulo, Brazil

Emmanuel A. Burdmann, MD, PhD

Background

Estimated glomerular filtration rate (eGFR) equations based on serum creatinine (Scr)(eGFRcr) combined or not with serum cystatin C (Scys) present worse accuracy in patients with low body mass index (BMI). This analysis aims to evaluate the impact of sarcopenia, defined by computed tomography (CT), on the performance of the CKD-EPI equations without race based on Scr and Scys in patients with cancer.

Methods

We included adult patients undergoing treatment for solid tumors between May 2017 and October 2017 and an abdominal CT scan within 90 days of measured GFR (mGFR) using the plasma clearance of ⁵¹Cr-EDTA. Body composition on an axial image at the third lumbar vertebral body level was performed using a previously validated machine-learning pipeline. Skeletal muscle index was defined as cross-sectional skeletal muscle area [cm²] divided by the square of the patient's height [m²]. Sarcopenia was defined using independently established cutoffs of skeletal muscle index (< 39 cm²/m² for women, < 55 cm²/m² for men).

Results

Of 465 included patients (50% women, mean age 58 [14] y), 34% had sarcopenia. Mean (SD) mGFR was 78.0 (22.5) ml/min/1.73 m². The table shows the performance of eGFR equations by sarcopenia and BMI categories. Even in patients with high BMI, those with sarcopenia had large eGFRcr overestimation (median bias: -14.7 [-18.1, -11.6] ml/min/1.73 m²), and poor accuracy (1-P30: 41.7 [29.2, 52.8] %).

Conclusion

This is the first study to demonstrate large bias and poor accuracy for eGFRcr and eGFRcrcys in patients with CT-defined sarcopenia, demanding other instruments such as Scys or mGFR to assess GFR more accurately in this population. Overweight and obese patients might benefit from body composition analysis to unveil underlying sarcopenia.