Criterion validity of equations as alternatives to reference standards for assessing body composition and energy expenditure in amyotrophic lateral sclerosis - a systematic literature review

BACKGROUND & AIM: People living with amyotrophic lateral sclerosis (ALS) are at high risk of malnutrition, making it essential to monitor their nutritional status through measurements of body composition and energy expenditure. However, validity of equations, as alternatives to reference standards for assessing these parameters in ALS, is unclear. This systematic review evaluates criterion validity of equations to estimate body composition and energy expenditure in ALS.

METHODS: Four electronic databases (EMBASE, MEDLINE, CINAHL and Cochrane) were systematically searched from inception until July 7 th, 2025. Studies were included if criterion validity of an instrument or method for estimating body composition or energy expenditure was examined in people diagnosed with ALS. Methodological quality was assessed using the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) risk of bias checklist. Criterion validity was rated as sufficient (+), indeterminate (?) or insufficient (-) based on COSMIN criteria for good measurement properties. Results were qualitatively summarised.

RESULTS: Twelve studies were included: five evaluated the criterion validity of equations to estimate body composition using Bioelectrical Impedance Analysis (BIA) or anthropometry, and seven to estimate resting or total daily energy expenditure. No equation was rated as sufficient for criterion validity across studies.

CONCLUSION: Equations to estimate body composition and energy expenditure should be applied with caution, as no equation exhibited high criterion validity in ALS. ALS-specific equations require further validation, and ideally, new equations tailored to the unique physiological characteristics of ALS should be developed.

PROSPERO REGISTRATION NUMBER: CRD42024573509.