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Updated: Jul 19, 2026
An Experimental Paradigm for the Prediction of Post-Operative Pain (PPOP)
Published on: January 27, 2010
A systematic review of trial methodology, using the placebo groups of randomized controlled trials in paediatric
1Pain Clinic, Department of Anaesthesia and Intensive Care Medicine, Helsinki University Central Hospital, P.O. Box 140, FIN-00029 HUS, Finland. katri.hamunen@hus.fi
Insights
This review of pediatric analgesic trials found that while rescue analgesia needs varied, placebo groups effectively demonstrated study sensitivity. Future trial designs can be improved based on these findings for better pediatric pain research.
Area of Science:
- Pediatric Anesthesiology
- Clinical Trial Methodology
- Pharmacology
Background:
- Evaluating trial methodology in pediatric analgesic studies is crucial for accurate pain assessment.
- Systemic analgesics like paracetamol, NSAIDs, and opioids are commonly studied for acute postoperative pain in children.
- Many pediatric analgesic trials utilize prophylactic administration rather than treating established pain.
Purpose of the Study:
- To evaluate the methodology of randomized, placebo-controlled trials of systemic analgesics for acute postoperative pain in children.
- To identify areas for improvement in the design and sensitivity of pediatric analgesic trials.
- To assess the utility of placebo groups in demonstrating internal study sensitivity.
Main Methods:
- Systematic search of databases for randomized, placebo-controlled studies on pediatric postoperative pain.
- Inclusion of 40 studies from 83 meeting initial criteria.
- Analysis focused on pain outcomes, rescue analgesia criteria, and placebo group responses.
Main Results:
- Most analgesics were administered prophylactically; only two studies treated established pain.
- Need for rescue analgesia showed more significant differences between groups than time to first rescue or pain intensity.
- Placebo groups, with 21-100% receiving rescue analgesia, demonstrated study sensitivity and high pain levels (>30% maximum).
Conclusions:
- Methodological aspects of pediatric analgesic trials require improvement for future studies.
- Placebo control groups are valuable tools for demonstrating internal sensitivity in pediatric analgesic research.
- Standardized criteria for rescue analgesia are needed to enhance trial comparability and reliability.
Abstract:
Trial methodology was evaluated in paediatric analgesic studies. Databases were searched for randomised, placebo controlled studies of systemic paracetamol, NSAIDs and opioids administered for acute postoperative pain in children. Eighty-three studies met the inclusion criteria and 40 were included for the analysis. Analgesics were administered for established postoperative pain in two studies only. In all other studies they were administered in a prophylactic manner. As study design and sensitivity are particularly demanding in studies using pre-emptive dosing of analgesics, the placebo groups were analysed for issues of study sensitivity. Postoperative pain outcomes included pain scores in 34, rescue analgesia in 36, time to first rescue analgesia in 15, pain on activity in eight, number of patients with pain in six, pain relief in three, global efficacy rating in two and analgesic consumption via PCA in four studies. Twenty of 36 studies reported criteria for rescue analgesia that varied from 20 to 77% of the maximum pain intensity. Need of rescue analgesia showed more often differences between study groups than time to first rescue analgesia or pain intensity. Rescue analgesia was administered to 21-100% of the patients in the placebo groups where no other analgesics were given perioperatively. Most patients in the placebo groups had pain that was greater than 30% of the maximum. In conclusion, analysis of the methodology showed several aspects of trial design that can be improved in future studies. Placebo control groups can be used in paediatric analgesic studies to demonstrate internal sensitivity.
