The Psoas Muscle Index Is Associated with Prognosis in Elderly Patients Undergoing Cardiovascular Surgery

Background: Sarcopenia is associated with poor outcomes in elderly patients. However, current surgical risk assessment tools for cardiovascular surgery do not include the impact of sarcopenia. Objectives: This study aimed to assess whether the psoas muscle index, a numerical score used to assess sarcopenia, is associated with outcomes in elderly patients undergoing cardiovascular surgery. Methods: This nested case-control study evaluated patients aged ≥ 75 years who underwent elective cardiovascular surgery and were admitted to the intensive care unit at Jichi Medical University, Saitama Medical Center between January 1, 2016 and March 31, 2017. The case group (poor outcomes) included patients who either died or were transferred to a rehabilitation facility postoperatively. The control group (good outcomes) included patients who were discharged postoperatively. Clinical factors likely to affect patient outcomes were assessed, and the characteristics of the two outcome groups were compared using logistic regression analysis. Results: In total, 183 patients were evaluated; among them, 137 and 46 patients were categorized to the good and poor outcome groups, respectively. The psoas muscle index was significantly associated with outcome (odds ratio: 0.25; 95% confidence interval: 0.14 – 0.43; P 0.001). A psoas muscle index cut-off of 3.24 had a specificity, sensitivity, positive predictive value, and negative predictive value of 0.86, 0.63, 0.58, and 0.87, respectively, for predicting worse outcome at discharge. Conclusions: The psoas muscle index was strongly associated with discharge to home in patients aged≥ 75 years who underwent elective cardiovascular surgery. This finding suggests that the psoas muscle index might be useful in identifying the eligibility of older patients for cardiovascular surgery.