Sex-Dependent Risk of Postoperative Delirium and Mediating Effects of Family Visits

Sex-Dependent Risk of Postoperative Delirium and Mediating Effects of Family Visits: A Prospective Observational Study

Postoperative delirium is a common and serious complication after surgery, affecting 10-40% of older patients undergoing non-cardiac procedures. It is characterized by sudden changes in attention, awareness, and thinking that fluctuate throughout the day. Delirium is associated with longer hospital stays, higher mortality, worse long-term brain function, and substantially increased healthcare costs. While several risk factors are known, it remains unclear whether a patient's sex independently influences the risk of developing postoperative delirium, as existing studies have produced conflicting results and were often not designed to specifically examine sex differences.Family visitation is a promising non-drug approach to preventing delirium. Studies in intensive care patients have shown that those who receive family visits have a significantly lower risk of developing delirium. However, it is unknown whether men and women receive different amounts of family visits after surgery, and whether any such difference could help explain sex-based disparities in delirium risk. Given that traditional gender roles in caregiving persist, women - who often serve as primary caregivers in their families - may receive fewer visits when they themselves become patients.This prospective observational study led by the University of Zurich will enroll 471 patients aged 65 years or older undergoing non-cardiac surgery lasting at least 2 hours under general or spinal anesthesia. The primary aim is to determine whether female patients have a higher risk of developing postoperative delirium within three days after surgery compared to male patients. Delirium will be assessed twice daily using the 4 A's Test (4AT), a validated and standardized screening tool. The secondary aim is to evaluate whether female patients receive fewer family visits than male patients and whether any difference in visitation mediates the sex-dependent delirium risk. Family visits will be recorded using an anonymous sign-in sheet placed in the patient's room. The study does not involve any experimental interventions; all patients receive standard clinical care. Participation is voluntary, and withdrawal is possible at any time without affecting medical treatment.

Study Overview

• Status: Recruiting
• Conditions: Postoperative Delirium (POD); Sex Differences

• Study Type: Observational
• Enrollment (Estimated): 471

Contacts and Locations

Study Locations

• Switzerland
  • Zurich, Switzerland
    • Recruiting
    • UniversitätsSpital Zürich
    • Contact: Julian Rössler, M.D.; Phone Number: +41442551111; Email: julian.roessler@usz.ch

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients aged 65 and older who are having noncardiac surgery

Description

Inclusion Criteria:

• Informed consent as documented by signature;
• ≥65 years of age;
• Scheduled non-cardiac surgery with expected surgery duration ≥ 2 hours;
• Under either general or spinal anesthesia.

Exclusion Criteria:

• Known drug or alcohol abuse;
• Requirement for postoperative ventilation;
• Current participation in another study with an investigational drug;
• Inability to complete the study assessments.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Female; Female patients aged 65 years or above with scheduled non-cardiac surgery with expected surgery duration ≥ 2 hours under either general or spinal anesthesia.
Male; Male patients aged 65 years or above with scheduled non-cardiac surgery with expected surgery duration ≥ 2 hours under either general or spinal anesthesia.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Delirium	The primary outcome is presence of delirium as assessed by the 4AT test. A 4AT score of 4 or above will be used for dichotomous assessment of the primary outcome presence of delirium. Participants will be assessed daily in the morning and the evening.	Starting on postoperative day (POD) 1 and continuing until POD 3, or discharge - whichever comes first.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Family Visits	The secondary outcome is hours spend being visited. Visits shall be self-reported by the visiting party. All visits regardless of relation to the participant (e.g., family, friends, or colleagues) shall be reported. Visits should be recorded in hourly intervals, regardless of the number of visitors present (e.g., two visitors for one hour, or one visitor for one hour, should counted as the same).	Starting on postoperative day (POD) 1 and continuing until POD 3, or discharge - whichever comes first

Collaborators and Investigators

• Sponsor: Julian Rössler

Study record dates

Study Major Dates

• Study Start (Actual): May 5, 2026
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: March 25, 2026
• First Submitted That Met QC Criteria: March 25, 2026
• First Posted (Actual): March 31, 2026

Study Record Updates

• Last Update Posted (Actual): June 1, 2026
• Last Update Submitted That Met QC Criteria: May 27, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Mental Disorders; Postoperative Complications; Pathologic Processes; Confusion; Neurobehavioral Manifestations; Neurocognitive Disorders; Delirium; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Emergence Delirium
• Other Study ID Numbers: 2025-02296

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No