Purpose: Creatinine-based estimated glomerular filtration rate (eGFRCRE) may overestimate kidney function in patients with sarcopenia. While Cystatin C-based eGFR (eGFRCYS) is less affected by muscle mass, it may underestimate kidney function in patients with obesity. We sought to evaluate the relationship between body composition and discrepancies between creatinine and eGFRCRE and eGFRCYS in patients with cancer. Methods: We conducted a cross-sectional study of consecutive adults with cancer who had an abdominal CT scan performed within 90 days of simultaneous eGFRCRE and eGFRCYS measurements between May 2010-January 2022. Sarcopenia was defined using independent sex-specific cutoffs for skeletal muscle index (SMI) at the level of the third lumbar vertebral body (<39 cm2/m2 for women, <55 cm2/m2 for men). High adiposity was defined as the highest sex-specific quartile of total (visceral plus subcutaneous) adiposity index in the cohort. The primary outcome was eGFR discrepancy, defined by eGFRCYS >30% lower than eGFRCRE. We estimated the odds of eGFR discrepancy using multivariable logistic regression modeling. Results: Of 545 included patients (mean age 63 +/- 14 years, 300 [55%] females, 440 [80.7%] non-Hispanic white), 320 (58.7%) met the criteria for sarcopenia and 136 (25%) had high adiposity. After adjustment for potential confounders, sarcopenia and high adiposity were both associated with >30% eGFR discrepancy (adjusted odds ratio [aOR] 1.90, 95% confidence interval [CI] 1.12 to 3.24; aOR 2.01, 95% CI 1.15 to 3.52, respectively). Conclusion: Discrepancies in eGFRCRE and eGFRCYS are common in adult patients with cancer, and sarcopenia and high adiposity are both independently associated with large eGFR discrepancies.

Conflicts of interest: S. Gupta reports research support from BTG International and GE Healthcare. She is a member of GlaxoSmithKlines Global Anemia Council, a consultant for Secretome, and founder of the American Society of Onconephrology. MES: Reports research funding from Gilead, Merck, EMD Serono, and Angion. She has served as a scientific advisory board member to Mallinckrodt, Travere, and Novartis. DEL reports research support from BioPorto, BTG International, and Metro International Biotech LLC. FJF received unrelated research funding from the William M. Wood Foundation, has a related patent WO2019051358A1, and is a consultant for Pfizer. JFG has served as a compensated consultant or received honoraria from Bristol-Myers Squibb, Genentech/Roche, Takeda, Loxo/Lilly, Blueprint Medicine, Gilead, Moderna, AstraZeneca, Curie Therapeutics, Mirati, Merus Pharmacueticals, Nuvalent, Pfizer, Novartis, Merck, iTeos, Karyopharm, Silverback Therapeutics, and GlydeBio; research support from Novartis, Genentech/Roche, and Takeda; institutional research support from Bristol-Myers Squibb, Tesaro, Moderna, Blueprint, Jounce, Array Biopharma, Merck, Adaptimmune, Novartis, and Alexo; and has an immediate family member who is an employee with equity at Ironwood Pharmaceuticals. All remaining authors have no conflict of interest.

MES is funded by NIH grant R01DK130839 SG is funded by NIH grant K23DK125672 DEL is funded by NIH grants R01HL144566, R01DK125786, and R01DK126685 SJS is funded by NIH/NIA (K76AG074919) outside the submitted work  

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