Classifying sarcopenia: using median value or cut-off values?

Excerpt

We read with great interest the article by Eun Jin Song et al. published in Breast Cancer Research and Treatment entitled “Prognostic impact of skeletal muscle volume in breast cancer.” The authors showed that sarcopenia had prognostic impact in breast cancer. The authors suggested that muscle volume at L3 vertebra level obtained by computer tomography can be used to determine sarcopenia. They used median muscle volume to dichotomize patients as sarcopenic or not. Although sarcopenia has an prognostic impact in breast cancer, using median values is not the best way to determine sarcopenia. Median values are descriptive measures to analyze target population but can be misleading for diagnostic purposes. When you classify according to the median, you naturally set the upper limit of sarcopenia as 50% and some sarcopenic patients can be classified as “normal,” or vice versa. We propose that using common pre-specified cut-off values to define sarcopenia might be more useful and better feasible than median values. Previously, European Sarcopenia consensus [1] and sarcopenia definition for American population by Derstine et al. [2] determined cut-off values for sarcopenia for both European and American population. In Korean population, it was defined as 49 cm² m⁻² for men and 31 cm² m⁻² for women on L3 vertebra level muscle volume by KHANES study (Korean population, based on the Korea National Health and Nutrition Examination Study) [3]. Using cut-off values to define sarcopenia also provides comparability with other studies and reference for further studies. …