Resting energy expenditure measured by whole‐room and portable indirect calorimetry in adults with breast cancer: A comparison study

BACKGROUND: Accurate measurement of resting energy expenditure is essential for informing nutrition support and optimizing outcomes. However, gold standard methods for measuring resting energy expenditure are often unfeasible in clinical settings, and previous portable devices have lacked accuracy. We investigated the accuracy and reliability of a portable device to measure resting energy expenditure in patients with breast cancer. We also compared its performance with that of commonly used predictive equations. METHODS: In this cross-sectional study, Q-NRG (COSMED, Rome, Italy) accuracy was assessed by calculating the proportion of resting energy expenditure measurements within 10% of those obtained by a whole-room indirect calorimeter and by using Bland-Altman analysis. Reliability was evaluated using the intraclass correlation coefficient, analyzing complete 10-min and last 5-min tests. The Q-NRG accurately measured resting energy expenditure in ~70% of participants (~10% overestimations, ~20% underestimations). Individual-level agreement was better using complete test data (bias: -59 ± 124 kcal; limits of agreement: -301 to 183 kcal; absolute limits of agreement: 484 kcal). Good reliability was observed (intraclass correlation coefficient, complete tests = 0.895; last 5-min = 0.832). CONCLUSION: The Q-NRG demonstrated good group-level agreement and reliability for resting energy expenditure measurement. However, the wide variation suggests caution when interpreting individual results.