[Study of energy expenditure in anorexia nervosa: agreement between indirect calorimatry and several equations].

Unlabelled: Nutritional management is essential in anorexia nervosa (AN), although nutrient replenishment must be done progressively to prevent the occurrence of re-alimentation syndrome.

Objective: to compare resting enengy expenditure (REE) by means of indirect calorimetry and by different equations in AN female patients.

Material And Methods: we studied 21 women admitted for AN (DSM-IV), mean age 17 years (SD 5.9), range 12-34 years. Admission stay was 55.1 +/- 20.7 days (21-91). Initial nutritional assessment included anthropometrics (BMJ, TSF, SSE, MAC, MAMC) and tetrapolar bioimpedance (HoltainBC). Indirect calorimetry (IC) was done after overnight fasting (Deltatrac II MBM-200). In 9 patients, the same study was repeated before hospital discharge. We compared REE (Kcal/24 h) measured by IC with that obtained by several equations [Fleish, Harris- Benedict, FAO, Schofield-HW (SHW), Schebendach] through the intraclass correlation coefficient (ICC) and the Bland-Altman method.

Results: Nutritional status significantly improved during hospital admission. Fifty percent of the recovered weight was fat mass. REE significantly increased during admission. The equations overestimated REE as compared to IC (p < 0.05), except for the Schebendach equation that underestimated REE. The agreement between direct measurement of REE by IC and its estimation through equations was poor [Fleish (ICC = 0.21); HB (ICC = 0.21), SHW (ICC = 0.19), Schebendach (ICC = 0.15)]. Through the Bland-Altman method, we observed that there was a variable bias between IC and equations, with a clinically acceptable agreement for REW values of around 1200 Kcal/day.

Conclusions: 1) In our study we obtained a poor agreement between REW values measured by indirect calorimetry and those estimated by equations. 2) Through the Bland-Altman method, we observed that all equations present a variable bias as for IC, the agreement being clinically acceptable for REE values of around 1200 Kcal/day. 3) Thus, indirect calorimetry seems to be a very useful tool to calculate the energy requirements of anorexia nervosa patients.