A Predictive Model for Postoperative Analgesic Requirements After Abdominal Surgery

NCT07803575 | Not Yet Recruiting

• 2 other identifiers: 2026223-16373NMRR ID-26-02772-RUY
• Study Type: observational
• Target: 65
• Locations: 1 country
• Sites: 1

Brief Summary

Postoperative pain remains a common challenge after abdominal surgery despite the use of standard multimodal pain management strategies. Poorly controlled pain can delay recovery, limit early mobilisation, reduce patient comfort, and increase the risk of longer-term pain problems. This study aims to develop a predictive model to better understand and anticipate patients' postoperative pain relief needs after abdominal surgery. The study will observe adults undergoing elective abdominal surgery and collect information on their pain scores, pain medication use, surgical characteristics, and recovery during the first 48 hours after surgery. Participants will receive standard postoperative pain management according to usual clinical practice. The study will analyse patterns of rescue pain medication use, including when and how often additional pain relief is required after surgery. The collected information will be used to develop a model that can predict factors associated with increased pain medication requirements. The goal of this research is to improve understanding of individual differences in postoperative pain and provide a foundation for more personalised pain management strategies in the future. The findings may help healthcare providers identify patients who are more likely to require additional pain relief and support the development of safer and more effective approaches to postoperative pain control.

Conditions

Postoperative Pain; Postoperative Analgesia; Opioid Analgesic Requirement; Pain Management After Abdominal Surgery

Keywords

Postoperative Pain; Postoperative Analgesia; Patient-Controlled Analgesia; Repeated Time-to-Event Modelling; Pharmacokinetic-Pharmacodynamic Modelling; Model-Informed Precision Dosing

Outcome Measures

Primary Outcomes (1)

• Rescue Analgesic Administration Events During the First 48 Hours After Abdominal Surgery

  The number and timing of successful rescue analgesic events following elective abdominal surgery. A rescue analgesic event is defined as each successful patient-controlled analgesia (PCA) activation resulting in intravenous morphine delivery. The repeated occurrence and timing of rescue analgesic events will be analysed using repeated time-to-event modelling to characterise postoperative analgesic requirements.

  Up to 48 hours after completion of surgery

Secondary Outcomes (2)

• Postoperative Pain Scores

  At PACU arrival/ every 15 minutes during PACU stay/ every 4 hours up to 48 hours after surgery

• Morphine Exposure and Relationship With Rescue Analgesic Hazard

  Up to 48 hours after completion of surgery

Study Arms (1)

Adult Patients Undergoing Elective Abdominal Surgery

Adult patients aged 18-75 years undergoing elective open or laparoscopic abdominal surgery under general anaesthesia will be enrolled in this prospective observational cohort. Participants will receive standard postoperative analgesic management according to routine clinical practice. Rescue analgesia will be provided using intravenous morphine via patient-controlled analgesia (PCA), and the timing and dose of successful analgesic administrations will be recorded during the first 48 hours after surgery. Patient demographics, surgical characteristics, pain scores, and analgesic administration data will be collected to develop a predictive model of postoperative analgesic requirements.

Drug: Intravenous Morphine Patient-Controlled Analgesia

Interventions

Intravenous Morphine Patient-Controlled Analgesia DRUG

Participants will receive intravenous morphine via patient-controlled analgesia (PCA) as part of standard postoperative analgesic management following elective abdominal surgery. The study does not assign or modify analgesic treatment. Morphine PCA usage, including timing and dose of successful administrations, will be recorded to characterise postoperative analgesic requirements using repeated time-to-event modelling.

Adult Patients Undergoing Elective Abdominal Surgery

Eligibility Criteria

• Age: 18 Years - 75 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adults undergoing elective abdominal surgery under general anaesthesia will be enrolled in this prospective observational cohort study. The study population represents patients experiencing the early postoperative recovery phase, where pain trajectories and analgesic requirements vary substantially between individuals. Participants will be observed during the first 48 hours after surgery to characterise patterns of rescue analgesic use and postoperative pain. The study aims to develop a predictive model of postoperative analgesic requirements by integrating analgesic administration patterns with patient and surgical characteristics. The findings will support a better understanding of individual variability in postoperative pain management and provide a foundation for future personalised analgesic strategies.

You may qualify if:

• Adult patients aged 18-75 years
• American Society of Anesthesiologists (ASA) physical status I-III
• Elective open or laparoscopic abdominal surgery under general anaesthesia
• Expected postoperative ward or high-dependency unit (HDU) stay of ≥ 48 hours
• Ability to provide written informed consent in Bahasa Malaysia or English
• Ability to comprehend and self-report pain using the Numerical Rating Scale (NRS, 0-10)

You may not qualify if:

• Chronic opioid therapy, defined as regular opioid use for ≥ 4 weeks prior to surgery
• Severe hepatic impairment (Child-Pugh Class B or C) or severe renal impairment (eGFR \< 30 mL/min/1.73 m²)
• Known allergy or hypersensitivity to morphine or any opioid analgesic
• Cognitive impairment (documented diagnosis of dementia or delirium), language barrier, or communication deficit precluding reliable NRS self-report
• Documented history of substance use disorder (including opioid use disorder)
• Withdrawal of informed consent at any point

Sponsors & Collaborators

• Chaw Sook Hui: lead
• University of Malaya: collaborator

Study Sites (1)

Universiti Malaya Medical Centre

Kuala Lumpur, 59100, Malaysia

Location

Related Publications (7)

• Ahlers SJ, Valitalo PA, Peeters MY, Gulik Lv, van Dongen EP, Dahan A, Tibboel D, Knibbe CA. Morphine Glucuronidation and Elimination in Intensive Care Patients: A Comparison with Healthy Volunteers. Anesth Analg. 2015 Nov;121(5):1261-73. doi: 10.1213/ANE.0000000000000936.

  PMID: 26332855 BACKGROUND

• Xiberras M, et al. RTTE modelling of morphine PD for analgesia after paediatric cardiac surgery. PAGE 2024.

  BACKGROUND

• Goulooze SC, Krekels EH, Saleh MA, Ahlers SJ, Valitalo PA, van Dongen EP, van Schaik RH, Hankemeier T, Tibboel D, Knibbe CAJ. Predicting Unacceptable Pain in Cardiac Surgery Patients Receiving Morphine Maintenance and Rescue Doses: A Model-Based Pharmacokinetic-Pharmacodynamic Analysis. Anesth Analg. 2021 Mar 1;132(3):726-734. doi: 10.1213/ANE.0000000000005228.

  PMID: 33122543 BACKGROUND

• Juul RV, Nyberg J, Kreilgaard M, Christrup LL, Simonsson USH, Lund TM. Analysis of opioid consumption in clinical trials: a simulation based analysis of power of four approaches. J Pharmacokinet Pharmacodyn. 2017 Aug;44(4):325-333. doi: 10.1007/s10928-017-9522-4. Epub 2017 Apr 7.

  PMID: 28389762 BACKGROUND

• Juul RV, Rasmussen S, Kreilgaard M, Christrup LL, Simonsson US, Lund TM. Repeated Time-to-event Analysis of Consecutive Analgesic Events in Postoperative Pain. Anesthesiology. 2015 Dec;123(6):1411-9. doi: 10.1097/ALN.0000000000000917.

  PMID: 26495978 BACKGROUND

• Apfelbaum JL, Chen C, Mehta SS, Gan TJ. Postoperative pain experience: results from a national survey suggest postoperative pain continues to be undermanaged. Anesth Analg. 2003 Aug;97(2):534-540. doi: 10.1213/01.ANE.0000068822.10113.9E.

  PMID: 12873949 BACKGROUND

• Kehlet H, Jensen TS, Woolf CJ. Persistent postsurgical pain: risk factors and prevention. Lancet. 2006 May 13;367(9522):1618-25. doi: 10.1016/S0140-6736(06)68700-X.

  PMID: 16698416 BACKGROUND

MeSH Terms

Conditions

Pain, Postoperative

Condition Hierarchy (Ancestors)

Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Pain; Neurologic Manifestations; Signs and Symptoms

Central Study Contacts

Tsyr Xiang Teoh, Master of Anaesthesiology

CONTACT

+603-79494422; teohtx@um.edu.my

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Target Duration: 2 Days
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Associate Professor of Anaesthesiology

Study Record Dates

• First Submitted: July 25, 2026
• First Posted: September 3, 2026
• Study Start (Estimated): January 1, 2027
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): June 1, 2028
• Last Updated: September 3, 2026

Record last verified: 2026-09

Locations

MY (1)