Prevalence and clinical characteristics of low skeletal muscle index among adults visiting a health promotion center: Cross-sectional study

Sarcopenia causes a variety of functional impairments and is associated with all-cause mortality, but once it occurs, it is difficult to treat and reverse. However, the prevalence of sarcopenia in healthy people has never been investigated due to the low awareness of sarcopenia in healthy people. This cross-sectional study was conducted in a single health promotion center from the January 1st 2020 to the December 31st 2021. Adults aged 18 years and older with an Inbody as part of their health checkup were included, and all data was collected from the EMR. Obesity was defined as a body mass index (BMI) of 23 (kg/m(2)) or more by Korean standards, and low skeletal muscle mass was defined as a skeletal muscle index (SMI) of <0.789 for men and <0.512 for women. 60.5% of the total participants (n = 5993) had low skeletal muscle mass. The low SMI group had lower BMI, waist circumference, and abdominal skinfold than the normal SMI group (low SMI group vs normal SMI: BMI; 25.47 ± 2.96 vs 22.98 ± 3.05, P < .001, waist circumference; 90.31 ± 8.80 cm vs 82.69 ± 9.71 cm, P < .001, abdominal skinfold; 18.78 ± 2.44 mm vs 15.99 ± 2.12 mm, P < .001). The body fat percentage was higher in the low SMI group than in the normal SMI group 25.30 ± 6.23% versus 29.82 ± 7.07%, P < .001. Triglyceride and uric acid levels were low in the low SMI group (TG; 147.69 ± 97.27 vs 115.86 ± 68.31, P < .001, uric acid level; 6.30 ± 1.38 vs 5.23 ± 1.30, P < .001) and high-density lipid (HDL) was high (HDL; 53.17 ± 11.41 vs 59.89 ± 14.72, P < .001). The odds ratio of low SMI prevalence for age, sex, BMI, fat body percent, and triglycerides relative to normal SMI was 1.05 (P = .031), 0.14 (P < .001), 0.12 (P < .001), 2.05 (P < .001), and 0.99 (P = .003), respectively. Of those who visited the Health Promotion Center, more than 60% had low SMI identified through Inbody. Low BMI and high body fat percentage increase the risk of low SMI. Compared to normal and low SMI based on obesity, Sex, height, BW, abdominal skinfold, and waist circumflex showed significant P values in both groups. The factors related to low SMI were TG, HDL, and uric acid levels.