Higher body mass index is associated with more adverse changes in calf muscle characteristics in peripheral arterial disease

Objective: This study investigated whether higher body mass index (BMI) is associated with more adverse lower extremity muscle characteristics at baseline and more adverse changes in muscle over time among participants with lower extremity peripheral arterial disease (PAD). Methods: This was a longitudinal, observational study of 425 men and women with PAD and 261 without PAD. Computed tomography was used to measure calf muscle characteristics at baseline and every 2 years. Knee extension isometric strength, power, and 6-minute walk distance were measured at baseline and annually. Baseline BMI (kg/m ²) categories were ideal (20-25), overweight (>25-30), and obese (>30). Analyses adjust for age, race, sex, ankle brachial index, comorbidities, and other covariates. Results: At baseline, higher BMI among participants with PAD was associated with greater calf muscle area (ideal BMI: 5181 mm ²; overweight: 5513 mm ²; obese: 5695 mm ²; P =.0009 for trend), higher calf muscle percentage of fat (6.38%, 10.28%, 17.44%, respectively, P <.0001 for trend), lower calf muscle density (P <.0001 for trend), and higher isometric knee extension strength (P =.015 for trend). Among participants with PAD, higher BMI was associated with greater declines in calf muscle area (P =.030 for trend) and greater increases in calf muscle percentage of fat (P =.023 for trend). Among participants without PAD, there were no significant associations of baseline BMI with changes in lower extremity muscle outcomes over time. Conclusions: Among PAD participants, higher BMI is associated with greater calf muscle area at baseline. However, higher BMI is associated with more adverse calf muscle density and calf muscle percentage of fat at baseline and greater declines in calf muscle area over time.