This study aims to evaluate the utility of body mass index (BMI)-adjusted calf circumference (CC) in estimating skeletal muscle mass and diagnosing sarcopenia, as well as its association with falls, a common adverse event in sarcopenia. This study used cross-sectional and longitudinal designs.

The CC cut-off values and the diagnosis of sarcopenia were based on valid diagnostic criteria. BMI-adjusted CC was based on previous studies, with muscle mass measured by dual-energy X-ray absorptiometry.

To evaluate the diagnostic performance of BMI-adjusted CC for low muscle mass and sarcopenia, receiver operating characteristic curves were generated, and the area under the curve (AUC) values were compared using DeLong's test. Over a 1 year follow-up period, factors associated with falls were examined using logistic regression analysis.

In the study of 901 older adults (77.6 ± 6.1 years, 63.6% women), 38.1% of men and 42.1% of women had a BMI outside the 18.5-24.9 kg/m range. BMI-adjusted CC significantly lowered the AUC values for diagnosing low skeletal muscle mass and sarcopenia in both sexes (P < 0.001).

Longitudinal univariate logistic regression analysis in women revealed that unadjusted CC was not significantly associated with fall risk, whereas BMI-adjusted CC significantly reduced fall risk at higher values. However, this association was no longer present in the multivariate analysis.

The utility of BMI-adjusted CC in assessing skeletal muscle mass was not confirmed. The potential value of BMI-adjusted CC has been suggested regarding falls.

Further research is warranted to better elucidate these findings.