Postoperative PainNCT07803575
A Predictive Model for Postoperative Analgesic Requirements After Abdominal Surgery
An observational study of Postoperative Pain and Postoperative Analgesia, run by Chaw Sook Hui at 1 site in Malaysia.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 75 years
- Conditions the study is for
- Postoperative Pain, Postoperative Analgesia, Opioid Analgesic Requirement
- Type of treatment
- Injection or infusion
- How many people
- 65 participants
- Where
- 1 siteMalaysia
- Study dates
- Jan 2027to Jun 2028
- How long will I take part?
- 2 Days
- Phase
- Observational
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 75 years
- All sexes
- No healthy volunteers
- Adult, Older adult
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.
Who may be able to join
- 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)
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Malaysia1 site
Universiti Malaya Medical Centre
Kuala Lumpur, 59100
SOOK HUI CHAW, PHD, +603-79494422, sh_chaw@um.edu.my
About this study
Official title: Quantitative Analysis of Postoperative Analgesia Following Abdominal Surgery Using Repeated Time-to-Event Modelling of Rescue Analgesic Administration
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.
Read more
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.
Read the detailed description
Postoperative pain remains a significant clinical challenge following abdominal surgery. Although multimodal analgesic strategies are widely implemented, many patients continue to experience moderate-to-severe pain during the early postoperative period and require repeated rescue analgesic administration. Current approaches to evaluate postoperative analgesic requirements often rely on total opioid consumption or time to first rescue analgesia. However, these methods may not fully capture the dynamic and repeated nature of postoperative pain and analgesic demand.
This study aims to develop a predictive model to characterise postoperative analgesic requirements in adults undergoing elective abdominal surgery. The study will use repeated time-to-event pharmacokinetic-pharmacodynamic modelling to analyse the timing and pattern of rescue morphine administration during the first 48 hours after surgery.
This is a prospective observational cohort study involving adult patients undergoing elective open or laparoscopic abdominal surgery under general anaesthesia. Participants will receive standard postoperative analgesic management according to routine clinical practice. No changes to clinical care will be introduced as part of the study.
Data collected will include patient demographics, surgical characteristics, anaesthetic details, postoperative pain scores, and analgesic administration records. Rescue analgesic events will be captured from patient-controlled analgesia (PCA) device records, including the timing and dose of successful morphine administrations. Individual morphine exposure will be estimated using documented dosing histories and published population pharmacokinetic parameters.
The collected data will be analysed using repeated time-to-event pharmacokinetic-pharmacodynamic modelling. The model will evaluate factors influencing the likelihood of requiring rescue analgesia over time, including temporal patterns, circadian effects, morphine exposure, and patient or surgical characteristics. Model performance will be assessed using simulation-based evaluation methods, including predictive checks and bootstrap analysis.
The expected outcome of this study is the development of a validated predictive framework for postoperative analgesic requirements after abdominal surgery. This model may provide a foundation for future personalised analgesic strategies, allowing earlier identification of patients at higher risk of inadequate pain control and supporting safer, more effective postoperative pain management.
- Conditions
- Postoperative Pain, Postoperative Analgesia, Opioid Analgesic Requirement, Pain Management After Abdominal Surgery
- Being tested
- Intravenous Morphine Patient-Controlled Analgesia
- Keywords
- Postoperative Pain, Postoperative Analgesia, Patient-Controlled Analgesia, Repeated Time-to-Event Modelling, Pharmacokinetic-Pharmacodynamic Modelling, Model-Informed Precision Dosing
- Medical subject headings
- Pain, Postoperative
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Intravenous Morphine Patient-Controlled AnalgesiaDrug
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.
| Study group | Role | What they receive |
|---|---|---|
| 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. Receives: Drug: Intravenous Morphine Patient-Controlled Analgesia |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: Up to 48 hours after completion of surgery
Secondary outcomes (2)
Postoperative Pain Scores
Pain intensity measured using the Numerical Rating Scale (NRS; 0-10) at predefined postoperative time points, including before and after rescue analgesic administration.
Measured: 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
Relationship between predicted morphine plasma concentration derived from individual dosing histories and the hazard of subsequent rescue analgesic administration.
Measured: Up to 48 hours after completion of surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Sep 2026
- Study startJan 2027 (estimated)
- Primary completionJul 2027 (estimated)
- Study completionJun 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for Postoperative PainStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 65 participants (estimated)
- Target duration
- 2 Days
Sponsor and investigators
- Lead sponsor
- Chaw Sook Hui
- Sponsor type
- University, hospital or other
- Collaborators
- University of Malaya
- Responsible party
- Sponsor-investigator, Chaw Sook Hui, University of Malaya
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07803575
- Sponsor's protocol ID
- 2026223-16373
- Other IDs
- NMRR ID-26-02772-RUY
- Status last verified
- Sep 2026
- First submitted
- 25 Jul 2026
- Last updated
- 3 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: A formal plan for sharing individual participant data has not yet been established. Any future data sharing will be considered after completion of the study, publication of the primary findings, and approval by the relevant institutional ethics committee. If data sharing is undertaken, only de-identified data will be considered, and access will be subject to appropriate data protection measures and institutional requirements.
Publications
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.
PubMed 26332855Xiberras M, et al. RTTE modelling of morphine PD for analgesia after paediatric cardiac surgery. PAGE 2024.
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.
PubMed 33122543Juul 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.
PubMed 28389762Juul 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.
PubMed 26495978Apfelbaum 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.
PubMed 12873949Kehlet 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.
PubMed 16698416