Study designs of evaluations included in the review
Placebo-controlled trials with random or quasi-random (e.g. alternating patients) treatment assignment were eligible.
Specific interventions included in the review
Studies of opiate analgesia compared with placebo were eligible for inclusion. The included studies used buprenorphine, papaveretum, morphine sulphate, fentanyl, tramadol or oxycodone; administration was sublingual, buccal, intramuscular or intravenous. Where reported, the examiners in the clinical evaluations were surgical residents, emergency medicine (EM) physicians, EM residents, EM physician and surgical residents, 'paediatric EM', or surgeon.
Participants included in the review
Studies in participants with acute abdominal pain were eligible for inclusion. The included studies were in adult, adolescent and paediatric samples. Most studies enrolled patients with undifferentiated acute abdominal pain; a few included only patients with right lower quadrant pain. The final diagnoses in the included studies comprised a variety of conditions such as appendicitis, bowel obstruction or pancreatitis. Most studies excluded several patient groups, for example those with suspected abdominal aortic aneurysm or severe pain.
Outcomes assessed in the review
Studies that provided data on changes in the patient history assessment, physical examination or clinical management of patients were eligible for inclusion. The review addressed incidences of all changes in the history and physical examination of the abdomen, including changes in the presence of peritoneal signs, blinding of examiners as a substitute outcome for effects on patient history, and incidences of management errors in terms of delayed or unnecessary surgeries.
How were decisions on the relevance of primary studies made?
Two reviewers independently reviewed the studies; a third reviewer resolved any discrepancies.