Honig 1984.

Methods	Randomised, double blind, 4 parallel groups. Single oral dose Medication administered when baseline pain reached a moderate to severe intensity Pain assessed at 0, 30, 60 mins, then hourly to 6 hours
Participants	Various elective surgical procedures, including orthopaedic, abdominal and thoracic N = 116 M = 71, F = 45 Mean age 45 years
Interventions	Codeine 60 mg, n = 28 Paracetamol 600 mg, n = 28 Paracetamol + codeine 600/60 mg, n = 30 Placebo, n = 30
Outcomes	PI: standard 4 point scale PR: standard 5 point scale PGE: standard 5 point scale Use of rescue medication Adverse events: any, serious Withdrawals
Notes	Oxford Qualtiy Score: R1, DB2, W0. Total = 3
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	"Capsules were identical in appearance"