The results of this study have significant implications for clinical practice and guideline development. The current European guideline on postoperative Delirium prevention (ESAIC 2024) explicitly identifies a lack of large, adequately powered studies comparing different anesthetic techniques and is therefore currently unable to provide clear recommendations on the selection of an optimal technique. This study will close this knowledge gap and thus support future guideline recommendations. The results could show that a particular anesthetic technique (e.g., propofol) is associated with a significantly lower risk of postoperative delirium; if so, this would have immediate implications for modifying standard anesthesia protocols in hospitals.

Furthermore, Delirium is a significant public health challenge in aging societies. With demographic aging, the number of older patients undergoing surgery is continuously increasing. The societal costs of Delirium are estimated at several billion euros per year in major industrialized nations. A reduction in the incidence of postoperative Delirium by just 10% through optimization of the anesthetic procedure would therefore have major health economic implications.

This retrospective, single-center cohort study analyzes routine data from Charité - Universitätsmedizin Berlin and its clinical partners for the period from January 1, 2011, to January 31, 2026.

Inclusion Criteria:

• Adult patients (≥18 years) at the Department of Anesthesiology and Intensive Care Medicine (CCM/CVK) and the Department of Anesthesiology and Intensive Care Medicine (CBF) at Charité,
• undergoing elective surgery under general anesthesia
• with a planned surgery duration of ≥ 30 minutes

In addition, the following conditions must be met:

• The surgery must be the patient's first surgery per hospital stay to avoid dependencies and repeated measurements of the same person within a short time frame;
• The surgeries take place at Charité between January 1, 2011, and December 31, 2025.

Exclusion Criteria:

Patients in any of the following situations are excluded:

1. Cardiac surgery (this patient group requires specialized monitoring strategies and has postoperative delirium risk profiles that differ significantly from those of other types of surgery)
2. preoperatively diagnosed delirium, defined as positive results on the Nursing Delirium Screening Scale (NU-DESC) or the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) during preoperative evaluations;
3. severe preoperative cognitive impairment, defined as a Mini-Mental State Examination (MMSE) score <15 points, or
4. preoperatively documented severe dementia
5. neurosurgical procedures (neurosurgical patients require specialized monitoring protocols and differ from other surgical patients in their postoperative delirium (POD) symptoms)
6. Patients who were already admitted to intensive care units prior to their elective surgery (these patients already have increased mortality and a different risk profile)
7. Patients who were already intubated or sedated prior to surgery (this group cannot undergo standardized POD screening)
8. High preoperative risk for postoperative nausea and vomiting (PONV) (specifically, patients with documented PONV grade 3 or PONV grade 4 risk are excluded, as this group is indicated for anesthesia with propofol)

• Adult patients (≥18 years) at the Department of Anesthesiology and Intensive Care Medicine (CCM/CVK) and the Department of Anesthesiology and Intensive Care Medicine (CBF) at Charité,
• undergoing elective surgery under general anesthesia
• with a planned surgery duration of ≥ 30 minutes