Muscle mass evaluation in hospitalized patients: Comparison between doubly indirect methods

Loss of muscle mass (MM) in hospitalized patients has been associated with negative outcomes, thus, evaluating this biomarker is important to stratify risk. Although studies have been showing that calf circumference (CC) and bioelectrical impedance analysis (BIA) are valid for estimating MM in hospitalized patients, we do not know if they are associated. The aim of this study was to evaluate the associations between CC and BIA in hospitalized patients.

A cross-sectional study, in hospitalized patients' post-acute cardiac event. We collected sociodemographic, clinical, and anthropometric data. CC measurement was adjusted according to the BMI. Spearman's correlations and associations between the methods were performed for the total sample, according to sex and stage of life (older adults or not).

We included 177 patients, mean age of 60.5 ± 12.4 years old, the majority males (75 %). Median BMI was 26.2 kg/m² (23.8-29.2 kg/m²), most of them overweight (41.8 %). The median of CC was lower in females and older adults, and majority of the patients had low CC (87.6 %). Higher values of fat-free mass (FFM) by BIA were observed in males and younger adults, and 5.6 % presented low FFMI. We found a positive and moderate correlation between fat-free mass index (FFMI) and CC (rho = 0.532). Males had higher correlations (rho = 0.481). An increase of 1 kg in the FFM represented an increase of 1.16 cm (crude analysis) to 1.59 cm (adjusted analysis) in CC (p < 0.001). FFM explained 37 % in the variability of CC, and together with BMI, sex and age, explained 60 % in the variability.

Raw values of FFM obtained by BIA and CC presented a weak to moderate correlation in cardiac patients. Changes in one measure impact on the other one.