Association of Delirium and EuroSCORE II in Cardiac Surgery Patients

Patients undergoing cardiac surgery are at risk of developing delirium which is a frequent psychiatric condition found in ICU participants especially cardiac surgery patients. It presents with decreased levels of consciousness followed by a cognitive decline which is sometimes difficult to recognize along with altered sleep patterns. Hospital stay is increased for these patients, along with increased ICU stay which impacts morbidity and mortality and increases costs. The condition negatively impacts the post-op rehabilitation, quality of life and leads to social dependence for the patient, especially those who are older are at higher risks for long term cognitive dysfunction.

The diagnosis and monitoring of delirium remains a challenge because of the fluctuating course and different manifestations of the condition. There are wide variations in the incidence rates that are reported and are dependent on the diagnostic methods. The incidence of postoperative delirium in cardiac patients has been reported to be around 10-60 % and cognitive dysfunction occurs in up to 79% of these patients. Older patients have a high risk of developing deliriums in up to 73% of patients and in the ICU setting this rate is even higher up to 81%. Recognition of the disease can be helped with delirium rating scales and checklists but mostly is a clinical diagnosis. It is important to recognize the large number of risk factors that can be associated with the condition but more importantly the type of surgery can also impact the development of post-operative dementia. In CABG(Coronary Artery Bypass Grafting) the overall incidence of POD (Post Operative Delirium) was 7.9% while it was 11.2% after valvular surgery according to one study.

Patients undergoing cardiac surgery mostly require risk stratification and prediction models which are important tools for making medical decisions. One of the most used prediction models is the EuroSCORE II risk model, which includes 17 independent variables and considers 30 days' operative mortality. It is used for assessing the risk associated with heart surgery and is based on the European cardiac surgical database. Various studies have reported an association between higher scores on the EuroSCORE II system and the association with developing delirium.

With this, the investigators will study the association between EuroSCORE II and delirium in cardiac surgery patients and see if an increased preoperative EuroSCORE II leads to the development of delirium. It will help refute claims of the advantage of EuroSCORE II in predicting delirium after cardiac surgery. No such study has been performed in our country previously.

The rationale of this study is to see whether both the development of delirium and EuroSCORE II are independent of each other or if there is an association between the two.