The Importance of Muscle Mass Analysis in Acute Diseases

FOR RELATED ARTICLE, SEE PAGE 314The implications of muscle mass in different clinical scenarios have modified the way we think about muscle; it is now considered a crucial element in metabolism with endocrine and paracrine functions,1Tagliafico A.S. Bignotti B. Torri L. Rossi F. Sarcopenia: how to measure, when and why.La Radiologia Medica. 2022; 127: 228-237Crossref PubMed Scopus (38) Google Scholar rather than simply a mechanical organ. The study of muscle quality and quantity is one of the variables that define sarcopenia,2Cawthon P.M. Visser M. Arai H. et al.Defining terms commonly used in sarcopenia research: a glossary proposed by the Global Leadership in Sarcopenia (GLIS) Steering Committee.Eur Geriatr Med. 2022; 13: 1239-1244Crossref PubMed Scopus (23) Google Scholar and the distinction between these terms should always be acknowledged. FOR RELATED ARTICLE, SEE PAGE 314 Low muscle mass has been identified as a negative predictor for chronic diseases such as cancer or cirrhosis, and more recently with COVID-19.3Siahaan Y.M.T. Hartoyo V. Hariyanto T.I. Kurniawan A. Coronavirus disease 2019 (Covid-19) outcomes in patients with sarcopenia: a meta-analysis and meta-regression.Clin Nutr ESPEN. 2022; 48: 158-166Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar In this issue of CHEST, van Bakel et al4van Bakel S.I.J. Gietema H.A. Stassen P.M. et al.CT scan-derived muscle, but not fat, area independently predicts mortality in COVID-19.Chest. 2023; 164: 314-322Abstract Full Text Full Text PDF Scopus (2) Google Scholar describe an association between low cross-sectional area (CSA) muscle mass in CT scans of COVID-19 patients and in-hospital mortality. Although other studies have found low muscle mass to be involved in adverse outcomes in COVID-19 patients,3Siahaan Y.M.T. Hartoyo V. Hariyanto T.I. Kurniawan A. Coronavirus disease 2019 (Covid-19) outcomes in patients with sarcopenia: a meta-analysis and meta-regression.Clin Nutr ESPEN. 2022; 48: 158-166Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar the significance of this novel work is that this association remains in multivariate analysis after adjusting with the 4C mortality score. The precise mechanism of this association is yet to be determined, but a relationship between muscle mass and physiological reserve should be explored. One strength of this work is that it finally provides an example of how to intertwine a clinical score, such as the 4C mortality score for COVID-19, with muscle mass assessment. However, whether this extra effort is worth it is unclear. In this case, adding muscle mass to an already validated score5Martin J. Gaudet-Blavignac C. Lovis C. et al.Comparison of prognostic scores for inpatients with COVID-19: a retrospective monocentric cohort study.BMJ Open Respir Res. 2022; 9e001340Crossref PubMed Scopus (9) Google Scholar did not significantly increase its discriminatory performance, limiting the clinical applications of muscle mass. The use of muscle mass as a clinic parameter is still far from being widely available, for several reasons. First, there is no universal form of assessment, beginning with the fact that there are different software programs to analyze imaging CSA, which need a human hand to determine CSA, and assessment is time consuming. Second, a uniform cutoff value to define low muscular mass has not been agreed on, although efforts to expand these evaluations have been made.6Derstine B.A. Holcombe S.A. Ross B.E. Wang N.C. Su G.L. Wang S.C. Skeletal muscle cutoff values for sarcopenia diagnosis using T10 to L5 measurements in a healthy US population.Sci Rep. 2018; 811369Crossref PubMed Scopus (251) Google Scholar Third, CSA requires either a CT, which exposes the patient to radiation, or an MRI,7Albano D. Messina C. Vitale J. Sconfienza L.M. Imaging of sarcopenia: old evidence and new insights.Eur Radiol. 2020; 30: 2199-2208Crossref PubMed Scopus (168) Google Scholar which avoids radiation but is expensive and not widely available. Moreover, performing any of these imaging studies solely to assess body composition is not recommended. In the future, artificial intelligence would be a key tool to assess muscle mass more efficiently,8Hosch R. Kattner S. Berger M.M. et al.Biomarkers extracted by fully automated body composition analysis from chest CT correlate with SARS-CoV-2 outcome severity.Sci Rep. 2022; 1216411Crossref Scopus (3) Google Scholar as van Bakel et al4van Bakel S.I.J. Gietema H.A. Stassen P.M. et al.CT scan-derived muscle, but not fat, area independently predicts mortality in COVID-19.Chest. 2023; 164: 314-322Abstract Full Text Full Text PDF Scopus (2) Google Scholar discussed in their paper, and it will be a turning point in the process of developing a database9Linge J. Borga M. West J. et al.Body composition profiling in the UK Biobank imaging study: body composition profiling in UK biobank.Obesity (Silver Spring). 2018; 26: 1785-1795Crossref PubMed Scopus (90) Google Scholar of body composition in different populations for further understanding of their metabolic profiles. This will be a step forward in individualized medicine in any case scenario. Currently, most body composition literature is retrospective. But eventually, muscle mass measurement will be available for most patients, just like any other clinical parameter we use in our daily assessment, such as weight, and prospective studies will be developed to understand the complex and dynamic relationships between muscle and disease prognosis, so we would be able to incorporate these data into clinical scores as van Bakel et al4van Bakel S.I.J. Gietema H.A. Stassen P.M. et al.CT scan-derived muscle, but not fat, area independently predicts mortality in COVID-19.Chest. 2023; 164: 314-322Abstract Full Text Full Text PDF Scopus (2) Google Scholar did. Prompt identification of a patient with low muscle mass is important because it can be optimized with preconditioning programs, such as before surgery.10Hurst C. Robinson S.M. Witham M.D. et al.Resistance exercise as a treatment for sarcopenia: prescription and delivery.Age Ageing. 2022; 51afac003Crossref Scopus (45) Google Scholar However, would this be as possible or as favorable in an acute condition as in COVID-19? Unfortunately, we still do not have an answer to this question. Nevertheless, it has been described that simple interventions such as adjusting hospital menus can improve or prevent patients’ muscle loss.11Detopoulou P. Al-Khelefawi Z.H. Kalonarchi G. Papamikos V. Formulation of the menu of a general hospital after its conversion to a “COVID hospital”: a nutrient analysis of 28-day menus.Front Nutr. 2022; 9833628Crossref PubMed Scopus (11) Google Scholar Furthermore, if avoidance of muscle wasting by pharmacologic means ever becomes a real option, it may be the key to modifying the course of acute diseases. We have evidence that IL-6 receptor antibodies have been shown to decrease the detrimental effect of this cytokine in mice muscle12Tsujinaka T. Fujita J. Ebisui C. et al.Interleukin 6 receptor antibody inhibits muscle atrophy and modulates proteolytic systems in interleukin 6 transgenic mice.J Clin Invest. 1996; 97: 244-249Crossref PubMed Scopus (346) Google Scholar; research in this area remains to be explored. Although research in the field of body composition has answered some questions, it has also raised more areas for researchers to ideally evaluate not only muscle mass but also function and quality, as well as its physiologic role in acute disease and possible treatments. None declared. CT Scan-Derived Muscle, But Not Fat, Area Independently Predicts Mortality in COVID-19CHESTVol. 164Issue 2PreviewCT scan-derived low pectoralis muscle CSA is associated significantly with higher 30-day in-hospital mortality in patients with COVID-19 independently of the 4C Mortality Score. 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