Undernutrition, which implies an imbalance between energy intake and energy requirements, is common in patients with cystic fibrosis. The aim of this study was to compare resting energy expenditure determined by indirect calorimetry with that obtained with commonly used predictive equations in adults with cystic fibrosis and to assess the influence of clinical variables on the values obtained.

We studied 21 patients with clinically stable cystic fibrosis, obtaining data on anthropometric variables, hand grip dynamometry, electrical bioimpedance, and resting energy expenditure by indirect calorimetry. We used the intraclass correlation coefficient (ICC) and the Bland–Altman method to assess agreement between the values obtained for resting energy expenditure measured by indirect calorimetry and those obtained with the World Health Organization (WHO) and Harris–Benedict prediction equations.

The prediction equations underestimated resting energy expenditure in more than 90% of cases. The agreement between the value obtained by indirect calorimetry and that calculated with the prediction equations was poor (ICC for comparisons with the WHO and Harris–Benedict equations, −; 0.47 and 0.41, respectively). Bland–Altman analysis revealed a variable bias between the results of indirect calorimetry and those obtained with prediction equations, irrespective of the resting energy expenditure. The difference between the values measured by indirect calorimetry and those obtained with the WHO equation was significantly larger in patients homozygous for the ΔF508 mutation and in those with exocrine pancreatic insufficiency.

The WHO and Harris–Benedict prediction equations underestimate resting energy expenditure in adults with cystic fibrosis. There is poor agreement between the values for resting energy expenditure determined by indirect calorimetry and those estimated with prediction equations. Underestimation was greater in patients with exocrine pancreatic insufficiency and patients who were homozygous for Δ F508.

La desnutrición es frecuente en pacientes con fibrosis quística (FQ) e implica un desequilibrio entre la ingesta y los requerimientos. Nuestro objetivo ha sido calcular el gasto energético en reposo (GER) mediante calorimetría indirecta en adultos con FQ, compararlo con las fórmulas estimativas habitualmente empleadas y valorar la influencia de parámetros clínicos sobre el GER.

Estudiamos a 21 pacientes con FQ que se encontraban estables clínicamente. Se efectuaron medidas de parámetros antropométricos, dinamometría de mano, impedanciometría bioeléctrica y del GER medido por calorimetría indirecta (CI). Estudiamos la concordancia entre los valores del GER medidos y estimados por las fórmulas de la Organización Mundial de la Salud (OMS) y de Harris-Benedict (HB) mediante el coeficiente de correlación intraclase y el método de Bland-Altman.

Las ecuaciones infraestimaron el GER en más del 90% de los casos. La concordancia entre la CI y la estimada por las fórmulas fue escasa (para OMS, 0,47, y para HB, 0,41). Mediante el método de Bland-Altman observamos un sesgo variable entre la CI y las fórmulas, independiente de los valores del GER. La diferencia entre la CI respecto de la estimada por la fórmula de la OMS fue significativamente mayor en homocigóticos ΔF508 y en los pacientes con insuficiencia pancreática exocrina frente al resto.

En adultos con FQ, las fórmulas de la OMS y de HB infraestiman el GER. Hay una baja concordancia entre los valores del GER medidos y estimados. La infraestimación fue mayor en pacientes con insuficiencia pancreática exocrina y en homocigóticos ΔF508.