Prevalence of low calf circumference in hospitalized patients classified by raw or body mass index-adjusted values.

Background: Adiposity can influence the estimation of muscle mass using calf circumference (CC) and underestimate the frequency of low CC. An adjustment for CC using body mass index (BMI) was proposed to reduce this effect. We aimed to compare the low CC frequency in hospitalized patients when considering raw and BMI-adjusted values and explore data by sex, age, and race (white and non-white).

Methods: Secondary analysis from two cohort studies conducted with adult hospitalized patients using BMI and CC data collected in the first 72 h after hospital admission. We classified low CC by two approaches: (1) raw CC; (2) BMI-adjusted CC for patients with BMI ≥ 25. Cutoff values for low CC were ≤34 cm (men) and ≤33 cm (women).

Results: Among 1272 patients (54.1 ± 15.3 years old; 51.7% women; 82.1% White race), low CC frequency was 30.6% and low BMI-adjusted CC was 68.9%. For all elevated BMI categories, the low CC frequency was higher when considering BMI-adjusted values (P < 0.001). Low CC was more frequent (P < 0.001) in older adults (38.7% by raw; 79.1% by BMI-adjusted value) than in younger adults (27.6% by raw; 65.2% by BMI-adjusted value) and it was not associated with race. Low CC by raw values was more frequent in men than in women (35.0% versus 26.4%; P = 0.001), but did not differ between sexes when classified by BMI-adjusted values (70.7% versus 67.1%; P = 0.184).

Conclusion: Low CC BMI adjusted was 2.2 times more frequent in comparison with raw CC values, and it was identified in >60% of patients with BMI ≥ 25.