A Predictive Model for Postoperative Analgesic Requirements After Abdominal Surgery
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.
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.
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Intervenção / Tratamento
Descrição detalhada
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.
Tipo de estudo
Tipo de estudo
Inscrição (Estimado)
Inscrição
Contactos e Locais
Contato de estudo
Contato de estudo
- Nome: Tsyr Xiang Teoh, Master of Anaesthesiology
- Número de telefone: +603-79494422
- E-mail: teohtx@um.edu.my
Locais de estudo
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Kuala Lumpur, Malásia, 59100
- Universiti Malaya Medical Centre
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Contato:
- SOOK HUI CHAW, PHD
- Número de telefone: +603-79494422
- E-mail: sh_chaw@um.edu.my
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Critérios de participação
Critérios de elegibilidade
Critérios de elegibilidade
Idades elegíveis para estudo
- Adulto
- Adulto mais velho
Aceita Voluntários Saudáveis
Método de amostragem
População do estudo
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.
Descrição
Inclusion Criteria:
- 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)
Exclusion Criteria:
- 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
Plano de estudo
Como o estudo é projetado?
Detalhes do projeto
Número de grupos/coortes
Coortes e Intervenções
Grupo / CoorteGrupo / Coorte |
Intervenção / TratamentoIntervenção / Tratamento |
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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.
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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.
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O que o estudo está medindo?
Medidas de resultados primários
Medidas de resultados primários
Medida de resultado |
Descrição da medida |
Prazo |
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Rescue Analgesic Administration Events During the First 48 Hours After Abdominal Surgery
Prazo: Up to 48 hours after completion of surgery
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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.
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Up to 48 hours after completion of surgery
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Medidas de resultados secundários
Medidas de resultados secundários
Medida de resultado |
Descrição da medida |
Prazo |
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Postoperative Pain Scores
Prazo: At PACU arrival/ every 15 minutes during PACU stay/ every 4 hours up to 48 hours after surgery
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Pain intensity measured using the Numerical Rating Scale (NRS; 0-10) at predefined postoperative time points, including before and after rescue analgesic administration.
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At PACU arrival/ every 15 minutes during PACU stay/ every 4 hours up to 48 hours after surgery
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Morphine Exposure and Relationship With Rescue Analgesic Hazard
Prazo: Up to 48 hours after completion of surgery
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Relationship between predicted morphine plasma concentration derived from individual dosing histories and the hazard of subsequent rescue analgesic administration.
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Up to 48 hours after completion of surgery
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Colaboradores e Investigadores
Patrocinador
Patrocinador
Colaboradores
Colaboradores
Publicações e links úteis
Publicações Gerais
- 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.
- 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.
- 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.
- Xiberras 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.
- 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.
- 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.
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Outros números de identificação do estudo
- 2026223-16373
- NMRR ID-26-02772-RUY (Identificador de registro: NMRR)
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