Title: Risk factors and outcomes associated with postoperative delirium after cardiac surgery

Funding body: Faculty of Medical Sciences, University of Rzeszow

Funding Awarded: 70,000 Polish zloty

Start & finish date: May 2020 - June 2021

Investigators: prof Kazimierz Widenka, Dr Agata Debowska, Prof Daniel Boduszek, Dr Beata Horeczy, Dr Claudia von Bastian, Prof Maciej Wnuk, Prof Anna Lewinska

Project summary: Delirium is characterised by the presence of disturbed consciousness, change in cognition, and/or perceptual disturbance. It can take a hypoactive form (common symptoms include inattention and lethargy) or a hyperactive form (aggressive behaviour, pulling catheters). Postoperative delirium (POD) lasting hours or longer, with or without lucid intervals, is a common and serious complication among adult patients undergoing cardiac surgery, affecting approximately 20-50% of patients. However, the incidence of POD is clinically under-recognised. Past research reported that a combination of patient underlying vulnerabilities (such as older age, depression, history of stroke) and perioperative factors (such as stress associated with surgery and hospital stay, type of anaesthesia) increases the risk of POD. POD has also been shown to be associated with longer lengths of intensive care unit (ICU) stay, increased mortality, and cognitive decline (Brown, 2014; Marcantonio, 2017; Saczynski et al., 2012; Sanders et al., 2011). Hypoactive POD is more frequent than hyperactive POD and is associated with a poorer prognosis (Kiely et al., 2007; Yang et al., 2009). Despite the high incidence of POD and its serious consequences, the mechanisms leading to such acute confusion are poorly understood. Importantly, most published studies into both risk factors and consequences of POD are underpowered, which limits the clinical usefulness of findings. More research focusing on malleable risk factors in particular is needed for better prevention of POD. One promising avenue for such research offering easy preventive solutions is the investigation of the role of stress associated with hospital stay and surgery in POD development. Further, there is a paucity of studies isolating the effect of POD by accounting for other risk factors predicting similar outcomes. As such, the unique effect of POD on short- and long-term patient outcomes remains to be explored. The main aim of this prospective cohort study is to assess risk factors and outcomes of POD in adult patients undergoing elective cardiac surgery.