Calf Circumference Measurement Protocols for Sarcopenia Screening: Differences in Agreement, Convergent Validity and Diagnostic Performance

Abstract

Background: Although recommended by the Asian Working Group for Sarcopenia 2019 consensus (AWGS’19) as a screening tool for sarcopenia, there remains no consensus regarding the position (sitting, standing) or laterality (right, left) for the measurement of calf circumference (CC). This study aimed to determine the agreement between CC measurements, correlations with muscle mass and function, and diagnostic performance for sarcopenia screening.Methods: We studied 176 healthy community-dwelling older adults (mean age, 66.8±7.1 years) from the GERILABS-2 study. CC was measured using non-elastic tape in four ways: left and right sides in the sitting and standing positions. Sarcopenia was diagnosed using the AWGS’19 criteria. We produced Bland-Altman plots to assess the agreement, partial correlations for muscle mass and function to compare convergent validity, and area under the receiver operating characteristic curve (AUC) to compare diagnostic performance.Results: The prevalence rate of sarcopenia was 17.4%. Sitting CC was larger than standing regardless of laterality (right 35.31±2.95 cm vs. 34.61±2.74 cm; left 35.37±2.96 cm vs. 34.70±2.83 cm; both p<0.001), consistent with the systematic bias on Bland-Altman plots showing the overestimation of sitting over standing measurements (right bias=0.70 cm; 95% confidence interval [CI], -0.48–1.88; left bias=0.67 cm, 95% CI, -0.35–1.68). After adjusting for age and sex, CC was significantly correlated with appendicular skeletal mass, hand grip strength, knee extension, gait speed, chair stand, and short physical performance battery. Although right-sided CC measurements had better diagnostic performance (AUC=0.817), the difference was not statistically significant compared to the other positions (p>0.05). The optimal cutoff was <34 cm for all measurements, except for the left standing position (cutoff <35 cm).Conclusion: Standing CC measurements are recommended for sarcopenia screening in community-dwelling older adults because of their good agreement without systematic bias, convergent validity, and diagnostic performance.