Baird 1980.

Methods	R, DB, 5 parallel groups. Single oral dose Medication administered when baseline pain reached moderate to severe intensity Pain assessed at 0, 30, 60 min, then hourly up to 6 hours
Participants	Various surgical procedures, including orthopaedic, hernia, hysterectomy N = 156 (148 analysed for efficacy) M = 86, F = 60 Mean age 40 years
Interventions	Codeine 60 mg, n = 30 Zomepirac 50 mg, n = 30 Zomepirac 100 mg, n = 29 APC+codeine 60 mg, n = 29 Placebo, n = 30 (APC ‐ aspirin 454 mg, phenacetin 324 mg, caffeine 64 mg)
Outcomes	PI: standard 4 point scale PR: standard 5 point scale Use of rescue medication Adverse events Withdrawals
Notes	Oxford Quality Score: R1, DB2, W1. Total = 4 Rescue medication allowed after 2 h
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding? All outcomes	Low risk	"identical‐appearing capsules"