St Charles 1997.

Methods	Randomized, parallel group trial
Participants	110 children undergoing tonsillectomy with or without other procedures ASA status not stated Age 16‐168 months (mean 77, 67) Sex distribution: M/F (3.2, 3.2) Country: USA
Interventions	Ibuprofen 5 mg/kg orally postoperation Paracetamol up to 15 mg/kg and codeine 1 mg/kg orally postoperation
Outcomes	Bleeding requiring surgical intervention Bleeding requiring nonsurgical treatment Mild postoperative bleeding Pain (mild or moderate or severe) Nausea and emesis
Notes	Surgical technique included electro‐dissection or cold dissection and snare techniques.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomly assigned to one of two groups. No details given
Allocation concealment (selection bias)	Unclear risk	No details given.
Baseline Imbalances All outcomes	Low risk	Lots of surgical techniques but balanced. Demographic data clearly reported and largely equivalent
Blinding of participants and personnel (performance bias) 1. Perioperative bleeding requiring surgical intervention	High risk	Assumed no‐one blinded
Blinding of participants and personnel (performance bias) 2.Perioperative bleeding requiring non‐surgical intervention	High risk	Assumed no‐one blinded
Blinding of participants and personnel (performance bias) 3. Vomiting	High risk	Assumed no‐one blinded
Blinding of outcome assessment (detection bias) 1. Perioperative bleeding requiring surgical intervention	High risk	Inconsistencies in how data collected (some retrospectively from charts). No blinding. Not clear how bleeding detected. Parents in intervention group given free samples to take home
Blinding of outcome assessment (detection bias) 2. Perioperative bleeding requiring non‐surgical intervention	High risk	Inconsistencies in how data collected (some retrospectively from charts). No blinding. Not clear how bleeding detected. Parents in intervention group given free samples to take home
Blinding of outcome assessment (detection bias) 3. Vomiting	High risk	Nurses and parents not blinded ‐ responsible for reporting and recording any signs of PONV
Incomplete outcome data (attrition bias) All outcomes	Low risk	No incomplete data
Selective reporting (reporting bias)	Low risk	All expected outcome measures reported
Other bias All outcomes	High risk	Extra analgesics given in OR and during observation period. May affect vomiting outcomes. Inconsistencies mean that treatment was barely standardized