Risk Assessment for Postoperative Delirium

Postoperative delirium (POD) - a temporary state of confusion - is a frequent complication of surgery, which most commonly occurs in elderly patients. A tablet computer application that may assist preoperative risk screening for POD was developed at the University Hospital Basel in 2014. This study aims to investigate whether the computer program may assess the risk of a patient to develop POD.

Background:

Postoperative delirium (POD) - a temporary state of confusion - is a frequent complication of surgery, which most commonly occurs in elderly patients. Depending on the risk profile, 9-87% of patients are affected. Regarding the increasing age of surgical patients, prevention of POD is of even greater importance. New data lead to the assumption that medical preventive strategies may influence the frequency or at least the severity or duration of POD.

Preventive measures in patients at increased risk for developing POD could possibly be administered; however, clinical predictors for POD are rare and/or unspecific. Different scores and test batteries to assess the preoperative risk of POD have been developed, but these tools are time-consuming and require trained personnel.

In 2014, a tablet computer application was developed at the University Hospital Basel with the primary objective to assess the risk of developing POD in surgical patients. The first part records patient details, such as age, level of training, language, sensory impairment, and regular drug intake. The second part tests different cognitive functions, more precisely cognitive self-assessment, temporal orientation, episodic memory, working memory, attention, and executive functions. In contrary to already available tools, this application can be operated by the patient alone without the help of trained staff. It was tested in healthy individuals and patients with mild cognitive impairment and should now be evaluated in a clinical setting.

Study design:

Prospective observational cohort study with a derivation cohort including patients scheduled for elective non-cardiac surgery.

Number of participants:

Patients will be enrolled until a collective of 50 patients with POD is reached. Each study participant in the collective of delirious patients represents 2% in the final analysis. With an expected incidence of POD of 25%, an overall sample size of about 200 patients will be recruited.

Recruitment:

Eligible study participants (patients scheduled for surgery at the University Hospital Basel) will be identified from the appointments calendar of the Anesthesia Preoperative Evaluation Clinic.

Methods:

Before surgery, participating patients perform the tablet computer application to obtain a score. A high score attained in the application suggests a low risk to develop POD. The score is then compared with results of postoperative assessments conducted daily from day 1 after surgery. Outcome measures are the Delirium-Rating-Scale-Revised-98 (DRS-R-98), which can be used to diagnose delirium and assess its severity, the Delirium Observation Screening (DOS) Scale, and the Confusion Assessment Method (CAM). These assessments are repeated for 5 days until the patient is discharged or - if the patient develops delirium - until symptoms have subsided.

Endpoints:

Primary endpoint:

Correlation between the test score attained by the patient in the self-administered computerized test and the incidence of POD.

Secondary endpoint:

Correlation between the test score attained by the patient in the self-administered computerized test and the severity of POD.

Eligibility Criteria:
Inclusion Criteria:

* Elective major surgery
* Age ≥65 years
* Education ≥7 years
* Fluency in German language
* Informed written consent

Exclusion Criteria:

* Dementia (Mini Mental State Examination (MMSE) \<20 points)
* Surgical intervention that would limit verbal communication
* Cardiac surgery
* Thoracic/pulmonary surgery
* Intracranial surgery
* Former or present participation in a cognitive research project