Predicting patients at risk of early postoperative adverse events

Adverse events after surgery are common. Identification of markers of at-risk patients may facilitate efficient and effective perioperative resource allocation. This pilot study aimed to identify simple preoperative factors associated with postoperative adverse events. In 1291 surgical patients, the relationship between patient and surgical factors and adverse events in the post-anaesthesia care unit was examined using binomial logistic regression analysis. Adverse events in the postoperative care unit were common, including desaturation (13.6%), hypotension (5.8%) and apnoea (5.5%), with 19.9% of cases requiring attendance by an anaesthetist to manage unexpected complications. Average length of stay in the post-anaesthesia care unit was 120 minutes and prolonged stay for medical reasons was common. A number of patient and surgical factors, including surgical complexity, preoperative arrhythmia, previous anaesthetic issues and heart failure were strongly associated with these adverse events. Areas under receiver operating characteristic curves ranged from 0.63 to 0.80. Patients with adverse events in the post-anaesthesia care unit appeared to have a higher risk of intervention in postoperative wards from a medical emergency or intensive care unit team. Our preliminary findings suggest that preoperative identification of key factors may have utility in determining risk of early postoperative problems and hence, aid perioperative planning.