R. C. Dirks1, B. L. Edwards1, E. Tong1, B. Schaheen1, F. E. Turrentine1, A. L. Shada2, P. W. Smith1 1University Of Virginia,General Surgery,Charlottesville, VA, USA 2University Of Wisconsin,Surgery,Madison, WI, USA
Introduction: Sarcopenia, a loss of skeletal muscle mass associated with aging, is a practical measure of frailty and has been previously identified as a predictor of outcomes in surgical cohorts including cancer resection and elderly patients. We hypothesize that sarcopenia, as measured by preoperative CT scans of the psoas muscle, predicts mortality and morbidity in emergent laparotomy.
Methods: Institutional NSQIP data were queried for adult patients who underwent open emergency abdominal surgery between 2008 and 2013. Patient demographics, clinical variables, and outcomes were extracted from NSQIP. Patients with abdominal CT scans within 30 days prior to surgery were included and the cross sectional areas of the psoas muscles at vertebral level L4 were summed and normalized by patient height. Patients were assigned to sex-stratified tertiles based on this normalized total psoas area (TPA) for analysis, with the lowest tertile being classified as sarcopenic. Kaplan Meier curves were constructed to compare survival between TPA tertiles. Cox Proportional Hazards models stratified by sex and controlling for ASA score, ascites, International Normalized Ratio (INR), functional dependency and work Relative Value Units as a proxy for surgery complexity were used to evaluate the influence of TPA on postoperative mortality.
Results: NSQIP revealed 781 patients undergoing emergent open abdominal surgery and 593 of these (75.9%) had appropriate preoperative CT scans. Median patient age was 61 years (IQR 50-72), median TPA was 1719 mm2 (IQR 1341-2293), and median BMI was 26.7kg/m2 (22.9-33). Bivariable analysis demonstrated that TPA was significantly associated with total postoperative morbidity (p=0.013), increased length of stay (p<0.0001) and 90-day mortality (p=0.0008) but not 30-day mortality (p=0.26). Kaplan Meier curves demonstrated significantly decreased 90-day survival in lowest TPA tertile. A Cox proportional hazards model demonstrated that the impact of TPA was overwhelmed by previously validated predictors of mortality, most notably ASA score.
Conclusion: Sarcopenia, as measured by TPA, is significantly associated with increased 90-day mortality, length of stay, and total morbidity in patients undergoing open emergency abdominal surgery. Since many patients undergoing emergent abdominal surgery have already undergone CT scanning, TPA is readily available to the practicing surgeon at no added risk or cost. As such, sarcopenia is a convenient additional tool for preoperative risk assessment and risk counseling.
