Measuring Muscle Mass in Adults With Intellectual Disabilities: The Reliability and Construct Validity of Calf...

Area of Science:

• Human Physiology
• Clinical Assessment
• Intellectual Disabilities Research

Background:

• Sarcopenia diagnosis relies on muscle mass assessment.
• Bioelectrical impedance analysis (BIA) and calf circumference (CC) are methods for measuring muscle mass in adults with intellectual disabilities (ID).
• CC is more accessible and cost-effective than BIA for this population.

Purpose of the Study:

• To evaluate the construct validity and intrarater reliability of CC for estimating muscle mass.
• Comparison was made against BIA in adults with mild to moderate ID and cardiovascular risk factors (CVRF).

Main Methods:

• The study included 36 adults with ID from the PRET study.
• Construct validity was assessed using Pearson's correlations between CC and BIA-derived skeletal muscle mass (SMM), segmental muscle mass (SegMM), and skeletal muscle index (SMI).
• Intrarater reliability was determined using the intraclass correlation coefficient (ICC).

Main Results:

• Correlation coefficients between CC and SMM, SegMM, and SMI were 0.19, 0.60, and 0.69, respectively.
• The intrarater reliability (ICC) for CC measurements was excellent at 0.94.
• Confidence intervals for correlations indicated variability, particularly for SMM.

Conclusions:

• Calf circumference measurements demonstrate excellent intrarater reliability for adults with ID and CVRF.
• The construct validity of CC for estimating muscle mass, when compared to BIA, is questionable.
• Further research is needed to confirm CC's utility as a proxy for BIA in this population.