Increased resting energy expenditure (REE) has been hypothesized to be a potential cause of weight loss in individuals with Crohn's Disease (CD), mainly due to inflammatory response. This study aimed to develop and validate new predictive equations for REE in adults with CD. Adult patients aged between 18-65 years and with CD were recruited. Anthropometry, indirect calorimetry and bio-impedance analysis (BIA) were performed in all patients. New predictive equations were generated using two models: Model 1 with age, weight, height and CDAI as predictors, and Model 2 in which both bioimpedance-index (BI-index) and phase angle were added. Finally, accuracy prediction within ±10% was assessed and then compared with several published equations. A total of 270 CD patients (159 males, 111 females) were included and assigned to the calibration (n=180; age: 37.9±13years; BMI: 22.2±3.4kg/m2) and the validation groups (n=90; age: 38.5±13years; BMI: 22.7±3.7kg/m2). REE was directly correlated with weight (r=0.733, p=0.000) and BI-index (r=0.762, p=0.000). Models were both suitable for estimating REE at population level (bias: -0.2, bias: -0.3; respectively). Individual accuracy was high in both models (∼80%; 83%;respectively), unrelated to gender. Similarly, the Harris and Benedict, FAO and Schofield equations showed a good accuracy in males and females. Therefore, new equations specifically derived from CD patients provided a very good prediction of REE at population level. Interestingly, the formula based on raw-BIA variables was as accurate as those based on anthropometry, unrelated to gender. However, further studies are required to verify the application of those formulas and the role of raw-BIA variables in REE prediction.
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