Munro 1998.

Study characteristics
Methods	Parallel, interventions administered for 2 days, outcomes assessed for 4 days
Participants	PCA 39, control 41 Elective cardiac surgery
Interventions	PCA: morphine. Bolus/lockout/1 h limit: 1 mg/6 min/10 mg Control: SC morphine 0 to 7.5 mg every 1 to 2 h based on pain scores and nursing assessment of vital signs
Outcomes	Pain intensity and relief scores, at rest and on movement, opioid consumption; nausea and pruritus, patient satisfaction, success of physiotherapy and ease of obtaining preemptive analgesia before physiotherapy
Source of funding	Not mentioned
Notes	QS = 3 (R = 2, DB = 0, W = 1)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomization schedule
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	12 withdrawals occurred after randomization, but before interventions administered because of delays in extubation (numbers in each group not specified). Appears that remaining participants completed the study, but unclear how many participants contributed data
Selective reporting (reporting bias)	Low risk	All outcomes described in Methods section are reported in Results section
Other bias	Unclear risk	Small sample size