Trial Outcomes & Findings for REPOSE Study: Reducing Delirium by Enhancing Postoperative Sleep With Suvorexant (NCT NCT05733286)

Last Updated: 2026-01-15

Results Overview

Total sleep time (TST) on first postoperative night that patient received study drug, as measured by electroencephalography (EEG). Total sleep time includes amount of time in sleep during the lights out period (defined between 21:00 and 06:00).

Recruitment status

COMPLETED

Study phase

PHASE2

Target enrollment

142 participants

Primary outcome timeframe

The first postoperative night that the participants received study drug (D0)

Results posted on

2026-01-15

Participant Flow

Patients age 65 or older scheduled for non-cardiac elective surgery with planned postoperative overnight stay at Duke University Hospital and Duke Medical Pavilion were contacted to determine interest in enrollment in this study. Patients were consented in-person at preoperative visits or via electronic consent over telephone or videoconferencing.

14 participants were never assigned to a treatment arm due to screen fail (n= 4), withdrawal by PI (n = 4), subject chose to withdraw prior to surgery (n = 3), and surgery cancellation (n =3).

Participant milestones

Participant milestones
Measure	Suvorexant Arm Administer Suvorexant every evening for Post-Operative Day (POD) 0, 1, and 2	Placebo Arm Administer placebo every evening for Post-Operative Day (POD) 0, 1, and 2
Overall Study STARTED	68	60
Overall Study COMPLETED	66	57
Overall Study NOT COMPLETED	2	3

Reasons for withdrawal

Reasons for withdrawal
Measure	Suvorexant Arm Administer Suvorexant every evening for Post-Operative Day (POD) 0, 1, and 2	Placebo Arm Administer placebo every evening for Post-Operative Day (POD) 0, 1, and 2
Overall Study Never received study drug	2	3

Baseline Characteristics

REPOSE Study: Reducing Delirium by Enhancing Postoperative Sleep With Suvorexant

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Placebo Arm n=57 Participants Administer placebo every evening for Post-Operative Day (POD) 0, 1, and 2	Total n=123 Participants Total of all reporting groups	Suvorexant Arm n=66 Participants Administer Suvorexant every evening for Post-Operative Day (POD) 0, 1, and 2
Age, Continuous	72 years STANDARD_DEVIATION 5 • n=10 Participants	72 years STANDARD_DEVIATION 5 • n=24 Participants	71 years STANDARD_DEVIATION 4 • n=14 Participants
Sex: Female, Male Female	23 Participants n=10 Participants	51 Participants n=24 Participants	28 Participants n=14 Participants
Sex: Female, Male Male	34 Participants n=10 Participants	72 Participants n=24 Participants	38 Participants n=14 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=10 Participants	3 Participants n=24 Participants	3 Participants n=14 Participants
Race (NIH/OMB) Asian	0 Participants n=10 Participants	0 Participants n=24 Participants	0 Participants n=14 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=10 Participants	0 Participants n=24 Participants	0 Participants n=14 Participants
Race (NIH/OMB) Black or African American	7 Participants n=10 Participants	12 Participants n=24 Participants	5 Participants n=14 Participants
Race (NIH/OMB) White	46 Participants n=10 Participants	103 Participants n=24 Participants	57 Participants n=14 Participants
Race (NIH/OMB) More than one race	2 Participants n=10 Participants	2 Participants n=24 Participants	0 Participants n=14 Participants
Race (NIH/OMB) Unknown or Not Reported	2 Participants n=10 Participants	3 Participants n=24 Participants	1 Participants n=14 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	0 Participants n=10 Participants	2 Participants n=24 Participants	2 Participants n=14 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	54 Participants n=10 Participants	116 Participants n=24 Participants	62 Participants n=14 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	3 Participants n=10 Participants	5 Participants n=24 Participants	2 Participants n=14 Participants
Region of Enrollment United States	57 Participants n=10 Participants	123 Participants n=24 Participants	66 Participants n=14 Participants

PRIMARY outcome

Timeframe: The first postoperative night that the participants received study drug (D0)

Population: Participants with EEG data for total sleep time determination.

Outcome measures

Outcome measures
Measure	Suvorexant Arm n=62 Participants Administer Suvorexant every evening for Post-Operative Day (POD) 0, 1, and 2	Placebo Arm n=55 Participants Administer placebo every evening for Post-Operative Day (POD) 0, 1, and 2
Total Sleep Time (TST) on the First Postoperative Night	3.91 hours Standard Deviation 2.00	3.84 hours Standard Deviation 2.07

SECONDARY outcome

Timeframe: Postoperative Day 0 through Day 5

Population: Participants with 3D-CAM delirium severity scores collected.

Three minute Confusion Assessment Method (3D-CAM ) severity scores up through postoperative day 5 or discharge, whichever occurs first, in patients receiving suvorexant vs placebo. Scores range from 0-20 and the higher score is worse.

Outcome measures

Outcome measures
Measure	Suvorexant Arm n=66 Participants Administer Suvorexant every evening for Post-Operative Day (POD) 0, 1, and 2	Placebo Arm n=56 Participants Administer placebo every evening for Post-Operative Day (POD) 0, 1, and 2
Peak Postoperative Delirium Severity Score	2 score on a scale Interval 1.0 to 3.0	1 score on a scale Interval 1.0 to 3.0

OTHER_PRE_SPECIFIED outcome

Timeframe: Postoperative day 0-2

Using the electrographic headband data, differences in postoperative sleep architecture (including stage 2 and 3 NREM sleep and REM sleep) will be compared in participants who received suvorexant compared to those who received placebo using two-sample t-tests. No multiple comparison correction for multiple sleep stages is planned because these are exploratory analyses. Average total sleep time over all nights that participants receive study drug will also be compared using two-sample t-tests.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Postoperative days 1-5

To assess subjective sleep quality, the Richards-Campbell subjective sleep quality questionnaire will be administered daily from postoperative day 1-5 or until hospital discharge, whichever occurs first. The total subjective sleep quality score will be compared between placebo and suvorexant groups using a two-sample t-test.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Preoperative baseline and postoperative days 1-3

Pupillary unrest under ambient light is an index of spontaneous pupil fluctuations that occur secondary to activity of the locus coeruleus, an important brainstem nucleus involved in maintenance of wakefulness and attentional control. Decreased wakefulness has been associated with decreased pupillary unrest at ambient light, suggesting that pupillary unrest at ambient light is a marker of sleep deprivation-related alterations in wakefulness and attention. Here, infrared pupillometry will be used to measure participant's pupil diameter fluctuations under ambient light conditions both before surgery and daily up through postoperative day 3. We will compare postoperative changes in pupillary unrest at ambient light in both suvorexant and placebo-treated using a two-sided t-test.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: Preoperative baseline, and postoperative days 1-3

Sleep deprivation results in decreased ability to sustain attention, which can be measured with the 5-minute psychomotor vigilance task. The psychomotor vigilance task measures simple reaction times to a visual stimulus over a minute to assess for slowed responses and lapses (i.e., failed response to visual stimuli). Response times, speed, and lapses will be compared between suvorexant and placebo-treated groups to see if postoperative nightly suvorexant has an effect on these sustained attention measures. Using the NASA PVT+ application on an Apple iPad, the psychomotor vigilance task will be collected before surgery, and daily on postoperative day 1-3, or until hospital discharge, whichever occurs first. Analyses will examine pre-to-postoperative change in sustained attention measures to adjust for preoperative performance variability between participants.

Outcome measures

Outcome data not reported

OTHER_PRE_SPECIFIED outcome

Timeframe: From Postoperative day 0 up to 4 week follow up visit

Postoperative delirium occurs in up to 40% of older surgical patients and has been associated with prolonged hospital stays, long-term cognitive impairment, and increased one-year postoperative mortality. We will record the length of hospital stay for each participant.

Outcome measures

Outcome data not reported

Adverse Events

Suvorexant Arm

Serious events: 9 serious events

Other events: 14 other events

Deaths: 1 deaths

Placebo Arm

Serious events: 9 serious events

Other events: 13 other events

Deaths: 0 deaths

Serious adverse events

Other adverse events

Other adverse events
Measure	Suvorexant Arm n=66 participants at risk Administer Suvorexant every evening for Post-Operative Day (POD) 0, 1, and 2	Placebo Arm n=57 participants at risk Administer placebo every evening for Post-Operative Day (POD) 0, 1, and 2
Musculoskeletal and connective tissue disorders Leg Spasms	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Nervous system disorders Self-reported somnolence	3.0% 2/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Nervous system disorders Observed somnolence	12.1% 8/66 • Surgery (day 0) to 4-week follow-up call	12.3% 7/57 • Surgery (day 0) to 4-week follow-up call
Psychiatric disorders Abnormal Dreams	4.5% 3/66 • Surgery (day 0) to 4-week follow-up call	8.8% 5/57 • Surgery (day 0) to 4-week follow-up call
Psychiatric disorders Hypnagogic Hallucinations	3.0% 2/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call

Additional Information

Michael Devinney, MD, PhD

Duke University

Phone: 919-668-6266

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place

Measure	Suvorexant Arm n=66 participants at risk Administer Suvorexant every evening for Post-Operative Day (POD) 0, 1, and 2	Placebo Arm n=57 participants at risk Administer placebo every evening for Post-Operative Day (POD) 0, 1, and 2
Vascular disorders Pulmonary Embolus	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Injury, poisoning and procedural complications acute blood loss anemia from intraoperative aortic injury	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Injury, poisoning and procedural complications Increased Postoperative Pain	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Injury, poisoning and procedural complications Surgical Incision Swelling	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Metabolism and nutrition disorders Hypoglycemia	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Musculoskeletal and connective tissue disorders Gout	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Nervous system disorders Death due to persistent comatose state	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Nervous system disorders Intraparenchymal hemorrhage	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Nervous system disorders Multifocal Acute Brain Infarcts	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Nervous system disorders Transient Ischemic Attack	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Renal and urinary disorders Acute Kidney Injury	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Renal and urinary disorders Postoperative Urinoma	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Renal and urinary disorders Urinary Incontinence	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Respiratory, thoracic and mediastinal disorders Aspiration pneumonitis	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Vascular disorders Hemorrhagic Shock	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Vascular disorders Hypotension	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	3.5% 2/57 • Surgery (day 0) to 4-week follow-up call
Vascular disorders Pulmonary embolism	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Infections and infestations Wound dehiscence	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Infections and infestations Wound Infection	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Injury, poisoning and procedural complications Abdominal Fluid Collection	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Infections and infestations Postoperative Seroma Infection	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Infections and infestations Urinary tract infection	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Cardiac disorders Atrial Fibrillation	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Cardiac disorders Cardiac Arrest	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Cardiac disorders Intraoperative cardiac arrest	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Cardiac disorders Paroxysmal Atrial Tachycardia	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call
Infections and infestations Erythematous rash	0.00% 0/66 • Surgery (day 0) to 4-week follow-up call	1.8% 1/57 • Surgery (day 0) to 4-week follow-up call
Infections and infestations Postoperative Spinal Abscess	1.5% 1/66 • Surgery (day 0) to 4-week follow-up call	0.00% 0/57 • Surgery (day 0) to 4-week follow-up call