Surgical Apgar score is significantly useful as a predictor of major complications after thoracic spinal surgery: a retrospective cohort study

Abstract Background: Prediction of postoperative complications and management based on that prediction are important for improving outcomes. The surgical Apgar score, a simple score for surgical outcomes, has been used to predict postoperative complications. The purpose of this study was to investigate the usefulness of the surgical Apgar score to predict major complications after thoracic spinal surgery. Methods: The subjects were 104 patients who underwent thoracic spinal surgery at a single institution from 2014 to 2018. Background patient and disease characteristics assessed included age, gender, body mass index (BMI), comorbidities (diabetes, hypertension or coronary artery disease), anticoagulant and antiplatelet medications, preoperative hemoglobin, controlling nutritional status (CONUT) score, and American Society of Anesthesiologists-Physical Status (ASA-PS) classification. Surgical factors evaluated were operative time, approach, presence of instrumentation, and multiple intervertebral surgery. The surgical Apgar score was calculated from intraoperative estimated blood loss, minimum heart rate, and minimum mean blood pressure. Major complications were defined as unexpected elongation of intubation for more than 48 hours, postoperative blood transfusion (bleeding) of more than 4U in 72 hours, coronary artery disease, renal failure, cerebrovascular disease, sepsis, pneumonia, severe delirium, deep vein thrombosis, pulmonary embolism (PE), or wound complications. Postoperative hospitalization days were also investigated. A multivariate statistical analysis was performed using stepwise logistic regression. The occurrence of complications and the duration of postoperative hospitalization were compared using a t-test. A p-value of <0.05 was considered significant.Results: Major complications were observed in 19 (18.3%) patients; these were bleeding (8 patients), delirium and wound complications (4 patients each) PE (2 patients) and pneumonia and acute kidney injury (1 patient each). The multivariate analysis revealed that the surgical Apgar score (odds ratio=0.3) was significantly associated with major complications. Postoperative hospital stay was significantly longer in patients with complications (59 days) than in patients without complications (36 days; p=0.0015).Conclusion: The surgical Apgar score is an objective index that can be easily calculated from anesthesia records, and this study suggests that it may be useful in predicting major complications after thoracic spinal surgery.