Calf circumference to body mass index ratio: a new anthropometric indicator for ultrasound based sarcopenic obesity

Traditional anthropometric measurements, such as calf and arm circumference, may not accurately reflect muscle mass in obese individuals. These limitations highlight the need for more sensitive and practical measures for the early detection of sarcopenic obesity. This study aimed to evaluate the predictive value of the calf circumference to body mass index ratio (CC/BMI) as an anthropometric indicator for ultrasound based sarcopenic obesity, and to compare its effectiveness with calf circumference adjusted for BMI (subtracting 3, 7, or 12 cm from calf circumference measurements corresponding to BMI categories of 25-29.9, 30-39.9, and ≥ 40 kg/m², respectively).

A retrospective analysis was conducted on 573 patients aged 65 years and older from a geriatrics outpatient clinic. Exclusion criteria included having advanced dementia, knee or hip replacement, neurodegenerative diseases, decompensated heart failure or the use of muscle-impacting medications. Participants underwent geriatric assessments which included ultrasound measurements of anterior thigh muscle thickness and anthropometric evaluations. Sarcopenia was defined using the STAR index (anterior thigh muscle thickness/BMI ratio) and low handgrip strength. Patients who had both sarcopenia and a BMI ≥ 30 kg/m² were categorized as having sarcopenic obesity. CC/BMI, and calf circumference adjusted for BMI were calculated, and their predictive power for sarcopenic obesity was assessed.

Of the participants, 37.3% (n = 214) were sarcopenic, and 17.3% (n = 99) had sarcopenic obesity. Significant positive correlations were observed between the CC/BMI and age, as well as with handgrip strength, STAR index, and walking speed. The CC/BMI demonstrated a significantly higher predictive capability for sarcopenic obesity (AUC: 0.850, cutoff ≤ 1.20, sensitivity: 81.63%, specificity: 75.91%) compared to calf circumference adjusted for BMI (AUC: 0.672, cutoff ≤ 31 cm, sensitivity: 60.20%, specificity: 67.24%).

The CC/BMI shows higher sensitivity and predictive value for diagnosing sarcopenic obesity compared to calf circumference adjusted for BMI. It could serve as a practical screening tool for sarcopenic obesity in older adults.

Not applicable.