Effects of Sarcopenia and Myosteatosis on Postoperative Recovery in Elderly Patients after Surgery: A Retrospective Cohort Study

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Introduction: Few studies have assessed sarcopenia and myosteatosis identified by skeletal muscle parameters using thoracic Computed Tomography (CT) before surgery among elderly patients. This study aimed to investigate the prevalence of thoracic CT-defined sarcopenia and myosteatosis and evaluate their associations with perioperative outcomes in elderly patients undergoing surgery. Methods: This retrospective cohort study included elderly patients aged ≥65 years who underwent surgery with available preoperative thoracic CT imaging. Skeletal muscle abnormalities were assessed on chest CT at the T12 vertebral level. Patients were classified according to the presence of imagingdefined sarcopenia and myosteatosis. Baseline characteristics, intraoperative variables, and postoperative outcomes were compared between groups. Multivariable logistic regression and linear regression analyses were performed to evaluate the associations of sarcopenia and myosteatosis with perioperative outcomes. Results: Among the 195 elderly surgical patients, 43 (22.1%) were identified as having sarcopenia and 83 (42.6%) had myosteatosis. Compared with nonsarcopenic patients, those with sarcopenia were older and exhibited lower Body Mass Index (BMI), hemoglobin, albumin, and lipid levels, as well as a higher prevalence of ASA classification ≥3, previous stroke, and pneumonia history. Sarcopenic patients also showed increased intraoperative vasoactive drug use, prolonged recovery time, and longer total and postoperative length of hospital stay (LOS). In univariable analyses, sarcopenia was associated with increased risk of postoperative composite complications (OR 2.609, 95% CI 1.012-6.471, P = 0.041), longer total LOS (β 0.427, 95% CI 0.162-0.691, P = 0.002), and longer post LOS (β 0.316, 95% CI 0.066-0.566, P = 0.014); however, these associations were not maintained after multivariable adjustment. Sarcopenia was not an independent association with adverse outcomes after adjusting for variables. Patients with myosteatosis showed distinct baseline characteristics, including higher BMI, lower hemoglobin concentration, lower creatinine levels, and a different sex distribution compared with patients without myosteatosis. However, myosteatosis was not significantly associated with perioperative outcomes in either univariable or multivariable analyses. Discussion: Thoracic CT-defined sarcopenia may represent a marker of systemic vulnerability rather than an isolated indicator of muscle loss, whereas myosteatosis showed limited independent prognostic relevance. Opportunistic muscle assessment on routine chest CT may facilitate risk stratification in elderly surgical patients, although validation in larger cohorts incorporating functional measures is needed. Conclusion: Thoracic CT-defined sarcopenia is common among elderly surgical patients and is associated with markers of nutritional impairment, comorbidity burden, and delayed postoperative recovery. Although imaging-defined sarcopenia was not an independent predictor of adverse outcomes after adjustment, it may serve as an imaging marker of reduced physiological reserve and perioperative vulnerability. In contrast, myosteatosis alone showed limited prognostic relevance in this cohort. Routine assessment of skeletal muscle abnormalities on preoperative thoracic CT may provide additional information for perioperative risk assessment and patient optimization.