Author’s Reply: Is Sarcopenia More Than Just Low Body Mass?

We would like to thank Piyade et al. for their insightful comments regarding our article, “Sarcopenia Is a Risk Factor for Postoperative Complications Among Older Adults with Inflammatory Bowel Disease.”¹ As noted by Piyade et al., sarcopenia is a multifaceted condition characterized by a depletion in muscle mass, strength, and function.² We also agree that although it is critical to assess all 3 domains for future prospective work, much of the prior literature has focused only on assessments of muscle mass.

To date, retrospective studies of muscle mass among all-aged individuals with inflammatory bowel disease (IBD) have led to heterogeneous conclusions. While some have reported a significant association between sarcopenia and the need for medical or surgical rescue therapy, others have found no association between sarcopenia and the need for hospitalization or surgery.^3,4 This is due to the differing methodologies used to measure muscle mass as well as define the presence/absence of sarcopenia. Thus, to further our understanding of the association between muscle mass and preoperative risk in IBD, we aimed to compare the different modalities for measuring muscle mass, as well as define it as both a continuous and categorical variable. Our study found that Skeletal Muscle Mass (SMI) had a significantly better capacity to predict adverse postoperative outcomes among older adults with IBD as compared to Total Psoas Index. Furthermore, when adjusting for clinically relevant variables, we found that for every 1-unit increase in SMI, the risk of an adverse postoperative outcome decreased by 12%. Although retrospective in nature, this study suggests that skeletal muscle mass may enhance our ability to risk-stratify individuals preoperatively.

However, while this work has laid the foundation, we very much agree with Piyade et al. that future prospective studies are now needed to assess the benefits of adding measures of muscle strength and function. Additional areas for further exploration also include a consideration of muscle quality, with other disease states finding that myosteatosis, defined as fat infiltration within muscle tissue, is associated with a higher risk for adverse postoperative outcomes.⁵

In conclusion, while we acknowledge that the definition of sarcopenia encompasses more than muscle mass alone, this study has now set the stage for both uniform assessments of muscle mass, as well as future prospective work incorporating both muscle strength and function. To this end, we have ongoing recruitment efforts for a prospective study that includes both muscle mass and strength measures, and thank Piyade et al. for initiating this important dialogue.

Funding

None declared.

Conflicts of Interests

The authors confirm that there are no conflicts of interest noted below that may be considered a competing interest. A.S.F. has received consulting honoraria from Bristol Meyers Squibb, Takeda, Abbvie, and Eli Lilly, and has research funding support from the NIH/NIA (R03: AG078927-01; K76: AG083286-01A1), Crohn’s and Colitis Foundation, and American College of Gastroenterology.

Guarantor of the Article

Adam S. Faye, MD, MS.

References