Sheffield Institute for Translational Neuroscience, The University of Sheffield, Sheffield, UK.
College of Health, Wellbeing and Life Sciences, Sheffield Hallam University, Sheffield, UK.
Clin Nutr ESPEN. 2023 Oct;57:739-748. doi: 10.1016/j.clnesp.2023.08.017. Epub 2023 Aug 18.
People living with motor neuron disease (MND) frequently struggle to consume an optimal caloric intake. Often compounded by hypermetabolism, this can lead to dysregulated energy homeostasis, prompting the onset of malnutrition and associated weight loss. This is associated with a poorer prognosis and reduced survival. It is therefore important to establish appropriate nutritional goals to ensure adequate energy intake. This is best done by measuring resting energy expenditure (mREE) using indirect calorimetry. However, indirect calorimetry is not widely available in clinical practice, thus dietitians caring for people living with MND frequently use energy equations to predict resting energy expenditure (pREE) and estimate caloric requirements. Energy prediction equations have previously been shown to underestimate resting energy expenditure in over two-thirds of people living with MND. Hypermetabolism has previously been identified using the metabolic index. The metabolic index is a ratio of mREE to pREE, whereby an increase of mREE by ≥110% indicates hypermetabolism. We aim to critically reflect on the use of the Harris-Benedict (1919) and Henry (2005) energy prediction equations to inform a metabolic index to indicate hypermetabolism in people living with MND.
mREE was derived using VO₂ and VCO₂ measurements from a GEMNutrition indirect calorimeter. pREE was estimated by Harris-Benedict (HB) (1919), Henry (2005) and kcal/kg/day predictive energy equations. The REE variation, described as the percentage difference between mREE and pREE, determined the accuracy of pREE ([pREE-mREE]/mREE) x 100), with accuracy defined as ≤ ± 10%. A metabolic index threshold of ≥110% was used to classify hypermetabolism. All resting energy expenditure data are presented as kcal/24hr.
Sixteen people living with MND were included in the analysis. The mean mREE was 1642 kcal/24hr ranging between 1110 and 2015 kcal/24hr. When REE variation was analysed for the entire cohort, the HB, Henry and kcal/kg/day equations all overestimated REE, but remained within the accuracy threshold (mean values were 2.81% for HB, 4.51% for Henry and 8.00% for kcal/kg/day). Conversely, inter-individual REE variation within the cohort revealed HB and Henry equations both inaccurately reflected mREE for 68.7% of participants, with kcal/kg/day inaccurately reflecting 41.7% of participants. Whilst the overall cohort was not classified as hypermetabolic (mean values were 101.04% for HB, 98.62% for Henry and 95.64% for kcal/kg/day), the metabolic index ranges within the cohort were 70.75%-141.58% for HB, 72.82%-127.69% for Henry and 66.09%-131.58% for kcal/kg/day, indicating both over- and under-estimation of REE by these equations. We have shown that pREE correlates with body weight (kg), whereby the lighter the individual, the greater the underprediction of REE. When applied to the metabolic index, this underprediction biases towards the classification of hypermetabolism in lighter individuals.
Whilst predicting resting energy expenditure using the HB, Henry or kcal/kg/day equations accurately reflects derived mREE at group level, these equations are not suitable for informing resting energy expenditure and classification of hypermetabolism when applied to individuals in clinical practice.
患有运动神经元病（MND）的人经常难以摄入最佳热量。常常伴发代谢亢进，这会导致能量稳态失调，促使营养不良和相关体重减轻的发生。这与预后较差和生存率降低有关。因此，确定适当的营养目标以确保充足的能量摄入非常重要。这最好通过间接热量法测量静息能量消耗（mREE）来实现。然而，间接热量法在临床实践中并不广泛使用，因此照顾 MND 患者的营养师经常使用能量方程来预测静息能量消耗（pREE）并估计热量需求。以前的研究表明，能量预测方程在超过三分之二的 MND 患者中低估了静息能量消耗。代谢亢进以前是通过代谢指数来识别的。代谢指数是 mREE 与 pREE 的比值，其中 mREE 增加≥110%表明代谢亢进。我们旨在批判性地反思使用 Harris-Benedict（1919 年）和 Henry（2005 年）能量预测方程来确定代谢指数，以指示 MND 患者的代谢亢进。
使用 GEMNutrition 间接热量计的 VO₂ 和 VCO₂ 测量来推导 mREE。pREE 由 Harris-Benedict（HB）（1919 年）、Henry（2005 年）和 kcal/kg/day 预测能量方程估计。REE 变化，描述为 mREE 和 pREE 之间的百分比差异，确定了 pREE 的准确性（[pREE-mREE]/mREE）x 100%，准确性定义为≤±10%。代谢指数阈值≥110%用于分类代谢亢进。所有静息能量消耗数据均以 kcal/24hr 表示。
共有 16 名 MND 患者纳入分析。平均 mREE 为 1642 kcal/24hr，范围为 1110 至 2015 kcal/24hr。当整个队列的 REE 变化进行分析时，HB、Henry 和 kcal/kg/day 方程都高估了 REE，但仍在准确性阈值内（HB 的平均值为 2.81%，Henry 的平均值为 4.51%，kcal/kg/day 的平均值为 8.00%）。相反，队列内的个体 REE 变化显示 HB 和 Henry 方程都不准确地反映了 68.7%的参与者的 mREE，kcal/kg/day 则不准确地反映了 41.7%的参与者的 mREE。尽管整个队列没有被归类为代谢亢进（HB 的平均值为 101.04%，Henry 的平均值为 98.62%，kcal/kg/day 的平均值为 95.64%），但队列内的代谢指数范围为 HB 为 70.75%-141.58%，Henry 为 72.82%-127.69%，kcal/kg/day 为 66.09%-131.58%，表明这些方程对 REE 的过度和低估。我们已经表明，pREE 与体重（kg）相关，个体越轻，对 REE 的预测越低。当应用于代谢指数时，这种低估会偏向于对较轻个体的代谢亢进进行分类。
虽然使用 HB、Henry 或 kcal/kg/day 方程预测静息能量消耗可以准确反映群体水平的衍生 mREE，但当应用于临床实践中的个体时，这些方程不适合用于告知静息能量消耗和代谢亢进的分类。
