CALCULATION OF TOTAL ENERGY EXPENDITURE IN ADULTS WITH CROHN'S DISEASE BY INDIRECT CALORIMETRY AND SIMPLE WEIGHT-BASED EQUATIONS: A COMPARATIVE STUDY.

Background: Patients diagnosed with Crohn's disease (CD) are at high risk of nutritional impairment due to the symptoms and the intense inflammatory response of the disease. The use of indirect calorimetry (IC) to assess resting energy expenditure (REE) proves to be a valuable alternative for more accurately determining the energy requirements of these patients.

Objective: The primary objective of this study was to compare the REE, increased by 20% (to account for diet-induced thermogenesis and daily energy expenditure), as measured by IC in patients at different stages of CD, with the total energy expenditure (TEE) calculated using the Simple Weight-Based Equation (30 kcal/kg and 35 kcal/kg).

Methods: Sessions for measuring REE were conducted using IC, along with the collection of clinical, biochemical, and anthropometric data. The clinical activity of CD was classified using the Harvey-Bradshaw Index (HBI), while endoscopic classification was assessed through the Simple Endoscopic Score in CD (SES-CD).

Results: A total of 60 adult patients diagnosed with CD in different disease phases were randomly evaluated, with 56.7% being male and 43.3% female, and a mean age of 39 years. The majority (76.7%) were of caucasian ethnicity, and 48.3% had completed high school. According to body mass index (BMI), 21.7% were classified as undernourished, 48.3% as eutrophic, 16.7% as overweight, and 13.3% as obese. Regarding disease activity classification based on the HBI, 50% were in the active phase and 50% in remission. Endoscopic classification revealed that 60% had findings indicative of active disease. The patients evaluated were diagnosed with Crohn's disease (CD) at an average age of 28.2 years, with the majority presen-ting ileocolonic involvement (61.8%) and a stenosing behavior (45.5%). Regarding biochemical serum analysis, the average values found were 12.5 g/dL for hemoglobin, 38.7% for hematocrit, and 15.7 mg/L for C-reactive protein. 58.3% of patients did not have fistulas. No agreement was found between the energy expenditure results measured by the weight-based formulas (30 kcal/kg and 35 kcal/kg) and IC (ICC <0.4), with the values obtained by simple weight-based equations being higher than those from IC. The result obtained using 30 kcal/kg showed slightly greater concordance with IC, but still with low agreement. In isolation, energy expenditure in male patients was statistically higher than in female patients. There was a statistically significant direct correlation between energy expenditure and hemoglobin levels, as well as statistically significant indirect correlations with age and age at diagnosis. The difference in energy expenditure between the methods was indirectly correlated with age, BMI, and age at diagnosis. No statistically significant correlations were found between energy expenditure and the behavior, location, or activity of Crohn's disease.

Conclusion: This study suggests that the use of IC would be more beneficial for younger patients, with lower BMI, or those diagnosed at a younger age, given the greater discrepancy between the methods evaluated in these cases. For other patients, the 30 kcal/kg weight-based formula remains a practical and more accessible option. However, it is undeniable and increasingly recognized that IC provides a more accurate assessment of energy requirements in different clinical conditions, and when used appropriately, it can enhance nutritional support and care.