Establishing Predictors of Acute Sarcopenia: A Proof-OfConcept Study Utilising Network Analysis

Dynamic changes in sarcopenia status following stressor events are defined as acute sarcopenia; it is currently unknown how to stratify risk. Prospective observational study involving elective colorectal surgery, emergency abdominal surgery, and medical pa tients with infections aged >= 70 years -old. Handgrip strength, muscle quantity (ultrasound Bilateral Anterior Thigh Thickness, BATT, and Bioelectrical Impedance Analysis), and muscle quality (rectus femoris echogenicity) were measured preoperatively in the elective group, and within 48hours, 7days after, and 13weeks after admission/surgery. Serum/plasma samples were collected preoperatively (elective group) and within 48hours of admission/surgery (all groups). LASSO models adjusting for baseline sarcopenia status were performed. Seventy-nine participants were included (mean age 79.1, 39.2% female). Chronic Obstructive Pulmonary Disease (COPD) (48hours beta 0.67, CI 0.59-0.75), and prescription of steroids during admission (48hours beta 1.11, CI 0.98-1.24) - 1.24) were positively associated with sarcopenia at 7days. Delirium was negatively associated with change in BATT to 7days (7days beta -0.47, CI -0.5- - - 0.44). COPD (Preoperative beta 0.35, CI 0.12-0.58) and delirium (48hours beta 0.13, CI 0.06-0.2) - 0.2) were positively associated with change in echogenicity to 7days in analysis including systemic biomarkers. Participants with sarcopenia at baseline had higher IL -7 concentrations during acute phase of illness (median 8.78pg/mL vs 6.52pg/mL; p=0.014). IL -1b within 48hours of admission/surgery was positively associated with sarcopenia status at 7days (beta 0.24, CI 0.06- 0.42). Patients most at risk of acute sarcopenia or reductions in muscle quantity and quality included those prescribed steroids, with COPD or delirium, or with heightened systemic inflammation.