Indirect calorimetry and estimated energy prescription in hospitalized cancer patients.

Abstract

e23335 Background: Indirect calorimetry is recommended as the reference method for individualized energy prescription in patients with cancer; however, fixed weight-based caloric targets remain widely used in routine clinical practice. This study evaluated how commonly prescribed targets of 35 and 50 kcal/kg/day compare with measured resting energy expenditure (REE) in hospitalized oncology patients. Methods: A retrospective analysis of consecutive indirect calorimetry measurements performed in an oncology and hematology inpatient ward between February 12, 2024, and October 21, 2025, was conducted. Resting energy expenditure was recorded in kcal/day and normalized per kilogram of measured body weight. Empirical caloric targets of 35 and 50 kcal/kg/day were simulated for each measurement. Agreement with measured REE was assessed using mean bias, percent error, and the proportion of estimates within ±10% of measured expenditure. Results: Fourteen indirect calorimetry measurements were analyzed. Mean body weight was 61.8 ± 9.7 kg, and mean measured REE was 1626.9 ± 279.4 kcal/day, corresponding to 26.9 ± 6.2 kcal/kg/day. A target of 35 kcal/kg/day overestimated measured REE by a mean of 537 ± 444 kcal/day, with a mean percent error of 36.3%. Only 28.6% of estimates were within ±10% of measured REE, while 71.4% exceeded measured expenditure by more than 20%. A target of 50 kcal/kg/day resulted in marked overestimation, with a mean bias of 1464.9 ± 564.9 kcal/day and a mean percent error of 94.7%. No estimates using 50 kcal/kg/day were within ±10% of measured REE, and 85.7% exceeded measured expenditure by more than 50%. Conclusions: In this real-world inpatient oncology cohort, measured resting energy expenditure clustered around 27 kcal/kg/day. Fixed caloric prescriptions of 35 kcal/kg/day frequently overestimated energy needs, while 50 kcal/kg/day led to substantial and systematic overfeeding. These findings support the use of indirect calorimetry when feasible and highlight the risks associated with high empirical calorie targets in hospitalized patients with cancer. Key findings from indirect calorimetry, n = 14. Metric Value Weight, kg 61.8 ± 9.7 Measured REE, kcal per day 1626.9 ± 279.4 Measured REE, kcal per kg per day 26.9 ± 6.2 Bias of 35 kcal per kg per day target, kcal per day +537 ± 444 Within ±10 percent of REE using 35 kcal per kg per day 28.6 percent Bias of 50 kcal per kg per day target, kcal per day +1464.9 ± 564.9 Within ±10 percent of REE using 50 kcal per kg per day 0 percent REE = resting energy expenditure. Bias represents prescribed minus measured energy expenditure.