November 2011

Which Equation Better Predicts Energy Expenditure in Amyotrophic Lateral Sclerosis?

The purpose of this study was to discover the best way to calculate REE for patients with Amyotrophic Lateral Sclerosis (ALS). ALS is a progressive neurodegenerative disease that affects motor neurons causing weakness of the skeletal muscle. In most cases ALS patients eventually experience respiratory complications. Inadequate energy intake will lead to muscle catabolism, kidney complications, and increased ALS progression. Over estimating calorie needs may lead to increased CO₂ production and increased ventilitory demand. Increased CO₂ production leads to further distress on the respiratory system. Currently there is no set policy for calculating energy needs for patients with ALS.

The researchers used three different equations to calculate REE: Harris Benedict, Mifflin-St. Jour, and Ireton-Jones. The study included 56 individuals with ALS, 25 women and 31 men. The ages ranged from 35-74 years old and included both familial and sporadic cases. The participants were divided into three groups based on ventilitory function. Ventilitory function was assed using Forced Vital Capacity (FVC), which is the most common indicator of respiratory function for ALS patients. Participation requirements included BMI >18 or <30 to avoid malnutrition or over-nutrition, any pre-existing condition know to increase REE, or a diagnosis of any pre-existing neurological disease. Each day REE was calculated by an indirect calorimetry using an open-circuit metabolic cart, a trained technician operated the metabolic cart. REE was measured by the metabolic cart (mREE) and was compared to the three different energy predicted equations (cREE) that were regularly used by the dietitians at the facility.

The data was analyzed using descriptive statistics. Researchers considered age, sex, Fat Free Mass (FFM), and disease progression. Linear regression was used to determine the strength of the association between the variables. Sample size calculations and other values were used from previously published studies on patients with ALS.

This study found that there was little difference between mREE and cREE when using Mifflin St. Jour and Harris Benedict. However Ireton-Jones energy predictions were significantly higher then the mREE, on average Ireton-Jones yielded 171 calories more then the mREE. Researchers also found that as ALS advanced cREE became less accurate. These finding are similar to other studies done on patients with ALS. This study differs in the fact that in addition to Harris Benedict, Mifflin-St. Jour also adequately assessed energy needs for patients in this trial. Based on this study the researchers feel that using Ireton-Jones for patients with ALS should be avoided due to the higher energy predictions and recommend using Harris Benedict or Mifflin-St. Jour.

Ellis, Amy C., Rosenfeld, Jeffery. (2011). Which Equation Best Predicts Energy Expenditure in Amyotrophic Lateral Sclerosis? Journal of the American Dietetic Association. 111(11), 1680-168. Retrieved from http://www.sciencedirect.com.proxy.lib.ilstu.edu/science/article/pii/S0002822311013721.