Estimating daily energy expenditure in individuals with amyotrophic lateral sclerosis

Abstract

Background: Patients with amyotrophic lateral sclerosis (ALS) experience progressive limb weakness, muscle atrophy, and dysphagia, making them vulnerable to insufficient energy intake. Methods to estimate energy requirements have not been devised for this patient group.

Objective: The goal was to develop equations to estimate energy requirements of ALS patients.

Design: We enrolled 80 ALS participants at varying stages of their illness and studied them every 16 wk over 48 wk. At each time, we determined total daily energy expenditure (TDEE) in the home setting over a 10-d period by using the doubly labeled water method. We then developed statistical models to estimate TDEE by using factors easily obtained during a routine clinical visit.

Results: The most practical TDEE models used the Harris-Benedict, Mifflin-St Jeor, or Owen equations to estimate resting metabolic rate (RMR) and 6 questions from the revised ALS Functional Rating Scale (ALSFRS-R) that relate to physical activity. We developed a Web-based calculator to facilitate its use. In the research setting, measuring body composition with bioelectrical impedance spectroscopy enabled the estimation of RMR with the Rosenbaum equation and the same 6 questions from the ALSFRS-R to estimate TDEE. By using these models, the estimate of TDEE for nutritional maintenance was ±500 kcal/d across the spectrum of ALS progression.

Conclusions: Our results emphasize the importance of physical function and body composition in estimating TDEE. Our predictive equations can serve as a basis for recommending placement of a feeding gastrostomy in ALS patients who fail to meet their energy requirements by oral intake.

Trial registration: ClinicalTrials.gov NCT00116558.

FIGURE 1.

The difference between TDEE (kcal/d) measured by DLW and RMR as estimated by the Harris-Benedict equation (15) in ALS. The abscissa indicates the difference between measured TDEE and RMR from the Harris-Benedict equation. The ordinate is the number of individual ALS participants in the histogram. The energy expenditure in some ALS subjects exceeded the RMR by >2000 kcal/d, whereas in other participants with advanced disease TDEE was at the RMR. The difference between TDEE and RMR was statistically determined in model 6 (see Table 1). ALS, amyotrophic lateral sclerosis; DLW, doubly labeled water; RMR, resting metabolic rate; TDEE, total daily energy expenditure.

FIGURE 2.

Bland-Altman analysis of models that estimated TDEE in reference to measured TDEE by using DLW. Estimated TDEE from model 1 (A; R² = 0.3648, n = 227, t = 11.3, P < 0.0001), from model 6 by using the Harris-Benedict equation (15) (B; R² = 0.2991, n = 246, t = 10.2, P < 0.0001), from model 7 by using the Mifflin-St Jeor equation (16) (C; R² = 0.3501, n = 246, t = 11.5; P < 0.0001), and from model 8 by using the Owen equation (17, 18) (D; R² = 0.2702, n = 246, t = 9.5, P < 0.0001). DLW, doubly labeled water; TDEE, total daily energy expenditure.