Determining the Cut-off Values for Sarcopenia in the Korean Elderly Population Using Bioimpedance Analysis.

Background: Bioimpedance analysis (BIA) is known to be a useful method for assessing sarcopenia because cost-effective and not involving radiation exposure. However, the cut-off values for sarcopenia using BIA have not yet been determined in the Korean population. Objectives: To establish the cut-off values for sarcopenia in the Korean elderly population with the use of BIA. Methods: Body composition assessed by BIA was obtained in 7,641 participants aged 20-34 years and 3,902 participants aged >= 65 years from data routinely collected during health examinations at Seoul National University Gangnam Center. Appendicular skeletal muscle mass was adjusted for height and weight. Gender-specific cut-points for class I and class II sarcopenia were defined as 1 and 2 standard deviations below the mean in the reference group aged 20-34 years, respectively. In addition, the gender-specific, lowest 20th percentile cut-offs for muscle mass in participants aged >= 65 years were determined. Results: The cut-offs for class I and class II sarcopenia in men for height-adjusted appendicular skeletal mass were 6.74 kg/m(2) and 5.96 kg/m(2) and for weight-adjusted appendicular skeletal mass were 29.4% and 27.4%, respectively; those in women for height-adjusted appendicular skeletal mass were 4.93 kg/m(2) and 4.35 kg/m(2), and for weight-adjusted appendicular skeletal mass were 25.6% and 23.9%, respectively. The lowest 20th percentile cut-offs for height-adjusted and weight-adjusted appendicular skeletal mass were 6.69 kg/m(2) and 28.9% in men, and 5.76 kg/m(2) and 24.5% in women, respectively. Based on the derived cutoffs, prevalence of class II sarcopenia in participants >= 65 years of age for height-adjusted and weight-adjusted appendicular skeletal mass was 3.7% and 3.5% in men, and 0.2% and 11.2% in women, respectively. Among the above-mentioned definitions, sarcopenia by height-adjusted appendicular skeletal mass was significantly associated with 2-year mortality in older participants. Conclusions: Muscle mass deficit in the Korean population can be assessed based on the cut-offs determined in this study using BIA.