b'Scientific Session Abstracts SUNDAY APRIL 21, 2024 31: PSOAS MUSCLE INDEX AS PREDICTOR OF WORSE OUTCOMES FOLLOWING MAJOR AMPUTATION FROM PERIPHERALVASCULAR DISEASEVeena Mehta MD, Mikayla Hurwitz MD, Meena Archie MD, Nina Bowens MDHarbor UCLA Medical CenterBackground: Frailty has been reported as a predictor of adverse outcomes after various surgical procedures. There are several models for defining frailty, including 5-factor modified frailty index, clinical frailty scale, and psoas muscle index. Psoas muscle index has been associated with higher postoperative mortality and complications after cardiac surgery, including aortic valvereplacement and CABG, as well as after lower extremity revascularization (Juszczac 2018 et al, Kondo et al 2022). Our objective was to assess psoas muscle index as a predictor of outcomes after major amputation in patients with peripheral vascular disease.Methods: We performed retrospective evaluation of patients undergoing major amputation (below-knee amputation, above-knee amputation) at a safety-net hospital from 2016-2022. Patients were evaluated based on CT scans within 6 months of amputation. Outcomes included post-operative 30-day mortality, wound complication, pneumonia, MI and 1 year mortality. Psoas muscle index was calculated using psoas muscle area measured from CT scans at the level of the L4 divided by the body surface area. We analyzed these using univariate and multivariate analysis comparing postoperative outcomes by gender and by psoas muscle index.Results: A total of 106 patients were analyzed (68 males, 38 females). Females were more likely to have an AKA at first operation (55% vs 27%, p=0.005) or require AKA within 30 days after BKA (25% vs 6%, 0.01). We defined low psoas muscle index as the lower 40th percentile of all patients. The mean psoas index for males was 1088, whereas the mean psoas index for females was 787.Patients with low psoas muscle index were significantly more likely to have an AKA rather than a BKA at the first operation (61% vs 31%, p=0.01), as well as require AKA within 30 days after BKA (20% vs 10%, p=0.02). When we stratified by sex, females with low psoas muscle index were more likely to have wound complications within 30 days of surgery (21% vs 60%, p=0.01).Conclusions: Our results found that low psoas muscle index is associated worse outcomes after major amputation, particularly in female patients. This data may be helpful for preoperative risk assessment and decision making regarding amputation level.82SOUTHERN CALIFORNIA VASCULAR SURGICAL SOCIETY'