Optimal cutoffs for low skeletal muscle mass related to cardiovascular risk in adults: The Korea National Health and Nutrition Examination Survey 2009–2010

The possible association between low skeletal muscle mass and cardiovascular disease (CVD) risk factors necessitates estimation of muscle mass even in subjects with normal body mass index (BMI). This study was aimed to investigate optimal cutoffs for skeletal muscle mass reflecting CVD risk factors and to evaluate the relationship between skeletal muscle mass and CVD risk factors in the general population and in subjects with normal BMI using these cutoffs. This cross-sectional study analyzed data from the Korea National Health and Nutrition Examination Survey 2009–2010. We enrolled 5120 men and 6559 women aged ≥20 years. Skeletal muscle index (SMI) was defined as the weight-adjusted appendicular skeletal muscle mass measured by dual-energy X-ray absorptiometry. Using receiver operating characteristic curve analyses, SMI cutoffs associated with CVD risk factors were determined. Lower SMI was significantly associated with an increased prevalence of CVD risk factors. The first cutoffs in men and women were 32 and 25 %, respectively, and the second cutoffs were 30 and 23.5 %. Subjects in stage I and stage II SMI categories showed increased prevalence and risk for several CVD risk factors. These tendencies persisted in the association between cardiometabolic characteristics and SMI even in subjects with normal BMI. Using cutoffs of low skeletal muscle mass reflecting CVD risk factors, lower skeletal muscle mass was associated with increased prevalence and risk of several CVD risk factors. A higher prevalence of cardiometabolic abnormalities was observed among subjects with normal BMI but low skeletal muscle mass.