Calf circumference as a screening tool for muscle mass in older adults of mixed ethnicities: Cutoff points based on dual-energy x-ray absorptiometry.

Abstract

Background: Calf circumference (CC) is a recognized proxy for muscle mass, yet few studies have established specific cutoff points across diverse populations. This study aimed to define CC cutoffs for detecting low muscle mass in older adults, using appendicular lean mass (ALM) from dual-energy x-ray absorptiometry (DXA) as the reference, stratified by sex and age.

Methods: A total of 254 adults ≥60 years of age were recruited from two outpatient clinics at the Reference Center for Older Adults of the Federal University of Minas Gerais. Participants underwent comprehensive geriatric assessments and DXA scans. CC was measured on the left leg. Low muscle mass was defined using the ALM index, and cutoff points were determined through receiver operating characteristic (ROC) curves. The participants were categorized through self-reported ethnicity.

Results: Most participants were female (63.0%), with a mean age of 81.4 ± 8.2 years. The most commonly identified race was White (49.4%), followed by mixed race (43.8%) and Black (6.8%). For men, the CC cutoff was 35.0 cm (AUC = 0.90; sensitivity = 90.2%, specificity = 72.6%), with no differences across age groups. For women aged 60-84, the cutoff was 34.0 cm (AUC = 0.74; sensitivity = 77.1%, specificity = 60.8%), and for those ≥85 years of age, the cutoff was 32.0 cm (AUC = 0.74; sensitivity = 86.8%, specificity = 58.3%). Ethnicity did not influence the results.

Conclusion: The proposed CC cutoffs provide a practical and low-cost method for identifying low muscle mass and supporting sarcopenia screening among ethnically diverse older adults.