I am writing to express concerns and seek clarification regarding a paper published in the Journal of Cachexia, Sarcopenia and Muscle titled ‘Diagnosis of sarcopenia by evaluating skeletal muscle mass by adjusted bioimpedance analysis validated with dual-energy X-ray absorptiometry’ [1].

Our company, InBody Co. Ltd., manufacturer of the InBody device used for the above paper, has identified certain issues with the content and would appreciate your assistance in addressing them.

Questions have been raised about the comparison between ASMI (ASM) as measured by the InBody device and the corresponding measurements obtained through dual-energy X-ray absorptiometry (DEXA). In the paper, it was addressed that skeletal muscle mass (SMM) was directly used as appendicular skeletal muscle mass (ASM). However, SMM includes the muscles in the trunk, whereas the DEXA measurements considered only the muscle mass in the four limbs. In other words, ASM is appendicular skeletal muscle mass in the right arm, left arm, right leg and left leg, and SMM is trunk skeletal muscle mass added to this value.

Therefore, based on the definitions provided in the paper, there appears to be an inherent discrepancy between the ASM measurements obtained from InBody and those from DEXA, which could lead to an overestimation of ASM when utilizing InBody data for comparison. This fundamental difference in measurement methodologies has raised concerns about the accuracy of the comparisons made in the paper.

To explain with the result sheet that has been used in the paper (from inbodyusa.com), it reflects that the addition of the lean mass in all extremities adds up to 28.6 kg, but the SMM is 39.69 kg.

As shown above, the SMM/Ht² and ASM/Ht² values differ about 3.6, reflecting the fact that this example result sheet is of a muscular body type. For general people, we would expect from 2 to 3, also described in the paper.

Thus, as stated in the paper, ‘A significant overestimation of ASM, hence ASMI, was observed in measurements by the BIA compared with DXA (p < 0.005) (Table S1).’ would have been inevitable as the ASM derived from InBody would have included the trunk, and the ASM from DEXA would have not.

If it is determined that the definitions were inaccurately applied in the original paper, our team is interested in publishing a counter paper to provide a more accurate interpretation of the data. We kindly request information on the steps and guidelines for submitting such a counter paper, should that become necessary.

We appreciate your attention to this matter and look forward to your response. Your guidance and assistance in resolving this issue are highly valued, as we are committed to maintaining the integrity of scientific research in the field of Cachexia, Sarcopenia and Muscle.

Thank you for your time and consideration.

Sincerely,

Jade Kim

我写信是为了表达对发表在《恶病质、肌肉减少症和肌肉杂志》上的一篇题为“通过调整的生物阻抗分析验证的骨骼肌质量来诊断肌肉减少症”的论文表示担忧并寻求澄清 [1]。

我们公司 InBody Co. Ltd. 是上述论文中使用的 InBody 设备的制造商，已发现内容存在某些问题，并希望您协助解决这些问题。

关于 InBody 设备测量的 ASMI （ASM） 与通过双能 X 射线吸收测定法 （DEXA） 获得的相应测量值之间的比较，人们提出了疑问。在论文中，解决了骨骼肌质量 （SMM） 直接用作附肢骨骼肌质量 （ASM） 的问题。然而，SMM 包括躯干中的肌肉，而 DEXA 测量仅考虑四个肢体的肌肉质量。换句话说，ASM 是右臂、左臂、右腿和左腿的附肢骨骼肌质量，而 SMM 是添加到该值的躯干骨骼肌质量。

因此，根据论文中提供的定义，从 InBody 获得的 ASM 测量值与从 DEXA 获得的 ASM 测量值之间似乎存在固有的差异，这可能导致在使用 InBody 数据进行比较时高估 ASM。测量方法的这种根本差异引发了人们对论文中所做比较准确性的担忧。

用论文中使用的结果表（来自 inbodyusa.com）来解释，它反映出所有四肢的瘦体重增加加起来为 28.6 公斤，但 SMM 为 39.69 公斤。

如上所示，SMM/Ht² 和 ASM/Ht² 值相差约 3.6，这反映了此示例结果表属于肌肉体型的事实。对于一般人来说，我们预计 2 到 3 个，论文中也对此进行了描述。

因此，正如论文中所述，“与 DXA 相比，在 BIA 的测量中观察到对 ASM 的显著高估，因此 ASMI（p < 0.005）（表 S1）。”这是不可避免的，因为从 InBody 得出的 ASM 将包括躯干，而来自 DEXA 的 ASM 则不会。

如果确定原始论文中的定义应用不准确，我们的团队有兴趣发布一篇反论文，以提供更准确的数据解释。如有必要，我们恳请提供有关提交此类反论文的步骤和指南的信息。

感谢您对此事的关注，并期待您的回复。我们非常重视您对解决此问题的指导和帮助，因为我们致力于维护恶病质、肌肉减少症和肌肉领域科学研究的完整性。

感谢您的时间和考虑。

 真诚地

Jade Kim