1764
CORRESPONDENCE
HEPATOLOGY, May 2015
carcinoma mortality in the middle-aged and elderly. HEPATOLOGY 2014; 59:2207-2215. 2. Wang P, Kang D, Cao W, Wang Y, Liu Z. Diabetes mellitus and risk of hepatocellular carcinoma: a systematic review and meta-analysis. Diabetes Metab Res Rev 2012;28:109-122.
C 2015 by the American Association for the Study of Liver Diseases. Copyright V View this article online at wileyonlinelibrary.com. DOI 10.1002/hep.27427 Potential conflict of interest: Nothing to report.
Which One Is Associated With Nonalcoholic Fatty Liver Disease? Small Muscle Mass or Large Fat Mass
To the Editor: We read the article by Hong et al.1 with great interest because the concept of sarcopenia has been emerging as a major issue in many fields. In the study by Hong et al., sarcopenia was defined by a state of decreased percent muscle mass as skeletal muscle mass index (SMI) of 1 SD below the sex-specific mean value. They reported that participants in the sarcopenia group had greater body mass index (BMI) as well as high body fat mass (percent), and sarcopenia was associated with nonalcoholic fatty liver disease even after adjusting for insulin resistance. However, in contrast to a large difference of total body fat mass between the normal and sarcopenia group (15.2 versus 20.0 kg), the difference of total body muscle mass was relatively small (43.3 versus 41.3 kg). Moreover, contrary to the normal group, the sarcopenia group had more women, who have a smaller muscle mass than men. Recently, there have been many studies about this problem,2 and the Foundation for the National Institutes of Health project group defined sarcopenia as progressive loss of skeletal muscle mass and low muscle function with aging.3 Therefore, decreased percent muscle mass in the study should be termed sarcopenic obesity or increased percent fat mass, rather than sarcopenia. Hong et al. verified the relationship between sarcopenia and nonalcoholic fatty liver disease with multiple logistic regression analyses adjusting age, sex, smoking status, physical activity, homeostasis model of insulin resistance, C-reactive protein, and 25[OH] vitamin D level. As we addressed, adjusting BMI or fat mass should be offered to evaluate the effect of muscle mass, because defining sarcopenia by only SMI can mistake sarcopenic obesity for sarcopenia. On the other hand, there is firm evidence that obesity is associated with nonalcoholic fatty liver diseases (NAFLD).4 Therefore, without considering the effect of higher fat mass, interpreting a harmful effect of decreased percent muscle mass on NAFLD as a result of decreased muscle mass seems to be inadequate. In conclusion, to explore the association of sarcopenia and NAFLD the effect of obesity or fat mass should be excluded. Furthermore, sarcopenia should be cautiously defined with decreased muscle mass and/or decreased muscle strength or performance, rather than solely with decreased percent muscle mass. SUN-WOOK KIM, M.D. HEE-WON JUNG, M.D., M.SC. Department of Internal Medicine Seoul National University Hospital Seoul, Republic of Korea
References 1. Hong HC, Hwang SY, Choi HY, Yoo HJ, Seo JA, Kim SG, et al. Relationship between sarcopenia and nonalcoholic fatty liver disease: the Korean Sarcopenic Obesity Study. HEPATOLOGY 2014;59:1772-1778.
2. Stenholm S, Harris TB, Rantanen T, Visser M, Kritchevsky SB, Ferrucci L. Sarcopenic obesity: definition, cause and consequences. Curr Opin Clin Nutr Metab Care 2008;11:693-700. 3. Dam T-T, Peters KW, Fragala M, Cawthon PM, Harris TB, McLean R, et al. An evidence-based comparison of operational criteria for the presence of sarcopenia. J Gerontol Ser A: Biol Sci Med Sci 2014;69: 584-590. 4. Marchesini G, Brizi M, Bianchi G, Tomassetti S, Bugianesi E, Lenzi M, et al. Nonalcoholic fatty liver disease: a feature of the metabolic syndrome. Diabetes 2001;50:1844-1850. C 2015 by the American Association for the Study of Liver Diseases. Copyright V View this article online at wileyonlinelibrary.com. DOI 10.1002/hep.27370 Potential conflict of interest: Nothing to report.
Reply: Aging and other risk factors are often accompanied by simultaneous changes in body composition that lead to decreased muscle mass and increased fat mass. Baumgartner et al. first defined sarcopenia as reduction in appendicular skeletal muscle mass divided by height squared (ASM/height2) of 2 standard deviations (SDs) or more below the normal means for a younger reference group.1 Although this definition have been used widely, Dr. Newman et al. have shown that this definition was highly correlated with body mass index and identified fewer overweight or obese individuals as sarcopenic.2 Janssen et al. proposed a definition of sarcopenia using the skeletal muscle mass index (SMI [%], skeletal muscle mass [kg]/weight [kg] 3 100).3 Kim et al. suggested that decreased percent muscle mass in our study should be named by sarcopenic obesity (SO) or increased fat mass, rather than sarcopenia. However, most previous studies defined SO as a combined application of sarcopenia and obesity definition. In the Korean Longitudinal Study on Health and Aging, Lim et al. defined sarcopenia using ASM/ height2 or ASM/Wt of
CORRESPONDENCE
HEPATOLOGY, May 2015
carcinoma mortality in the middle-aged and elderly. HEPATOLOGY 2014; 59:2207-2215. 2. Wang P, Kang D, Cao W, Wang Y, Liu Z. Diabetes mellitus and risk of hepatocellular carcinoma: a systematic review and meta-analysis. Diabetes Metab Res Rev 2012;28:109-122.
C 2015 by the American Association for the Study of Liver Diseases. Copyright V View this article online at wileyonlinelibrary.com. DOI 10.1002/hep.27427 Potential conflict of interest: Nothing to report.
Which One Is Associated With Nonalcoholic Fatty Liver Disease? Small Muscle Mass or Large Fat Mass
To the Editor: We read the article by Hong et al.1 with great interest because the concept of sarcopenia has been emerging as a major issue in many fields. In the study by Hong et al., sarcopenia was defined by a state of decreased percent muscle mass as skeletal muscle mass index (SMI) of 1 SD below the sex-specific mean value. They reported that participants in the sarcopenia group had greater body mass index (BMI) as well as high body fat mass (percent), and sarcopenia was associated with nonalcoholic fatty liver disease even after adjusting for insulin resistance. However, in contrast to a large difference of total body fat mass between the normal and sarcopenia group (15.2 versus 20.0 kg), the difference of total body muscle mass was relatively small (43.3 versus 41.3 kg). Moreover, contrary to the normal group, the sarcopenia group had more women, who have a smaller muscle mass than men. Recently, there have been many studies about this problem,2 and the Foundation for the National Institutes of Health project group defined sarcopenia as progressive loss of skeletal muscle mass and low muscle function with aging.3 Therefore, decreased percent muscle mass in the study should be termed sarcopenic obesity or increased percent fat mass, rather than sarcopenia. Hong et al. verified the relationship between sarcopenia and nonalcoholic fatty liver disease with multiple logistic regression analyses adjusting age, sex, smoking status, physical activity, homeostasis model of insulin resistance, C-reactive protein, and 25[OH] vitamin D level. As we addressed, adjusting BMI or fat mass should be offered to evaluate the effect of muscle mass, because defining sarcopenia by only SMI can mistake sarcopenic obesity for sarcopenia. On the other hand, there is firm evidence that obesity is associated with nonalcoholic fatty liver diseases (NAFLD).4 Therefore, without considering the effect of higher fat mass, interpreting a harmful effect of decreased percent muscle mass on NAFLD as a result of decreased muscle mass seems to be inadequate. In conclusion, to explore the association of sarcopenia and NAFLD the effect of obesity or fat mass should be excluded. Furthermore, sarcopenia should be cautiously defined with decreased muscle mass and/or decreased muscle strength or performance, rather than solely with decreased percent muscle mass. SUN-WOOK KIM, M.D. HEE-WON JUNG, M.D., M.SC. Department of Internal Medicine Seoul National University Hospital Seoul, Republic of Korea
References 1. Hong HC, Hwang SY, Choi HY, Yoo HJ, Seo JA, Kim SG, et al. Relationship between sarcopenia and nonalcoholic fatty liver disease: the Korean Sarcopenic Obesity Study. HEPATOLOGY 2014;59:1772-1778.
2. Stenholm S, Harris TB, Rantanen T, Visser M, Kritchevsky SB, Ferrucci L. Sarcopenic obesity: definition, cause and consequences. Curr Opin Clin Nutr Metab Care 2008;11:693-700. 3. Dam T-T, Peters KW, Fragala M, Cawthon PM, Harris TB, McLean R, et al. An evidence-based comparison of operational criteria for the presence of sarcopenia. J Gerontol Ser A: Biol Sci Med Sci 2014;69: 584-590. 4. Marchesini G, Brizi M, Bianchi G, Tomassetti S, Bugianesi E, Lenzi M, et al. Nonalcoholic fatty liver disease: a feature of the metabolic syndrome. Diabetes 2001;50:1844-1850. C 2015 by the American Association for the Study of Liver Diseases. Copyright V View this article online at wileyonlinelibrary.com. DOI 10.1002/hep.27370 Potential conflict of interest: Nothing to report.
Reply: Aging and other risk factors are often accompanied by simultaneous changes in body composition that lead to decreased muscle mass and increased fat mass. Baumgartner et al. first defined sarcopenia as reduction in appendicular skeletal muscle mass divided by height squared (ASM/height2) of 2 standard deviations (SDs) or more below the normal means for a younger reference group.1 Although this definition have been used widely, Dr. Newman et al. have shown that this definition was highly correlated with body mass index and identified fewer overweight or obese individuals as sarcopenic.2 Janssen et al. proposed a definition of sarcopenia using the skeletal muscle mass index (SMI [%], skeletal muscle mass [kg]/weight [kg] 3 100).3 Kim et al. suggested that decreased percent muscle mass in our study should be named by sarcopenic obesity (SO) or increased fat mass, rather than sarcopenia. However, most previous studies defined SO as a combined application of sarcopenia and obesity definition. In the Korean Longitudinal Study on Health and Aging, Lim et al. defined sarcopenia using ASM/ height2 or ASM/Wt of
