eP712 - Pre-operative Nutritional Risk Assessment Should Include CT-derived Body Composition Measures to Screen for Risk of Adverse Outcomes Among Colectomy Patients

Purpose/Background: Poor nutrition is related to decreased physiologic reserve, specifically loss of muscle mass (sarcopenia) and fatty replacement of muscle (myosteatosis), which increases risk of complications after colectomy. Existing nutrition screening measures are time-consuming and inadequate for measuring body composition, which limits pre-operative risk assessment. Computed tomography (CT) is a valuable tool for quantification of muscle mass. This study utilized an automated machine-learning approach to measure muscle mass and intensity on CT and determine the association with surgical outcomes.Methods/Interventions: Patient data was retrospectively reviewed using the ACS National Surgery Quality Improvement Program outcomes database for elective colectomy at a single institution between 2018 to 2021; imaging data was abstracted from the electronic health record. Patients were identified as malnourished if serum albumin was less than 3.5 g/dL or they had a diagnosis of clinical malnutrition. Skeletal muscle index (SMI) and skeletal muscle radiation attenuation (SMRA) were measured and established cut-points were used to define sarcopenia and myosteatosis. Outcomes included length of stay and any post-operative complication. Parametric and non-parametric analysis was performed.Results/Outcomes: The incidence of post-operative complications was 20.2% (n=502, mean age 61.5 years, 47.0% male). The majority (60.3%) had sarcopenia on imaging. Using clinical features, 31.5% (n=158) were diagnosed as malnourished. The malnourished group had greater incidence of post-operative complications (40.5 vs. 11%, p < 0.0001) and prolonged length of stay (57 vs. 10.2%, p < 0.0001); they had significantly less muscle mass measured by SMI (33.9  8.0 vs. 39.3  9.7 cm2/m2, p < 0.0001) and were more likely to be identified as sarcopenic (77.0 vs. 52.6%, p < 0.0001). Multivariate analysis determined SMI [OR: 0.95, CI:0.92-0.97] and SMRA [OR: 0.97, CI: 0.95 – 0.96] to be independent risk factors for increased length of stay. Males and females with higher SMI were less likely to have a complication (OR: 0.73; CI:0.68-0.98, p < 0.0001 and OR: 0.75, CI:0.69-0.97, p < 0.0001, respectively). Males with lower SMI (OR: 0.93, CI: 0.90-0.96, p=0.0003) and females with lower SMRA (OR: 0.96, CI:0.93-0.95, p=0.008) were more likely to have a prolonged length of stay. Only 40.1% (n=122) of patients with sarcopenia were identified as malnourished, which implies that clinical assessment alone may be unable to identify patients with increased risk of complications.Conclusion/

Discussion: This study demonstrates that pre-operative CT-based body composition analysis is a useful adjunct to nutrition assessment for identifying at-risk patients. Altered body composition represents impaired physiologic reserve that can dampen the recovery process and lead to greater risk of complications. Body composition using clinically obtained pre-operative CT scans can screen patients at high risk for complications and enable implementation of targeted prehabilitation interventions.