Clinically Relevant Cut-off Points for the Diagnosis of Sarcopenia in Older Korean People

Background: The optimal criteria applied to older Korean people have not been defined. We aimed to define clinically relevant cut-off points for older Korean people and to compare the predictive validity with other definitions of sarcopenia. Methods: Nine hundred and sixteen older Koreans (>= 65 years) were included in this cross-sectional observational study. We used conditional inference tree analysis to determine cut-off points for height-adjusted grip strength (GS) and appendicular skeletal muscle mass (ASM), for use in the diagnosis of sarcopenia. We then compared the Korean sarcopenia criteria with the Foundation for the National Institutes of Health and Asian Working Group for Sarcopenia criteria, using frailty, assessed with the Korean Frailty Index, as an outcome variable. Results: For men, a residual GS (GS(re)) of <= 0.25 was defined as weak, and a residual ASM (ASM(re)) of <= 1.29 was defined as low. Corresponding cut-off points for women were a GS(re) of <= 0.17 and an ASM(re) of <= 0.69. GS(re) and ASM(re) values were adjusted for height. In logistic regression analysis with new cut-off points, the adjusted odds ratios for pre-frail or frail status in the sarcopenia group were 3.23 (95% confidence interval [CI] 1.33-7.83) for the men and 1.74 (95% CI 0.91-3.35) for the women. In receiver operating characteristic curve analysis, the unadjusted area under the curve for Korean sarcopenia criteria in men and women were 0.653 and 0.608, respectively (p<.001). Conclusions: Our proposed cut-off points for low GS and low ASM should be useful in the diagnosis of sarcopenia in older Korean people.