Wasylak 1990.

Study characteristics
Methods	Parallel, interventions administered over approximately 48 h, outcomes assessed until discharge, questionnaire administered 2 weeks post‐discharge
Participants	PCA 20, control 18 Gynecologic surgery
Interventions	PCA: morphine. Bolus/lockout/4 h limit: 2 mg/5 min in recovery room then 1 mg/10 min/NR in the ward Control: recovery room 2 mg IV as necessary then IM morphine 5 mg to 20 mg (with promethazine) every 4 to 6 h prn
Outcomes	Pain intensity, opioid consumption, ambulation, LOS, respiratory function, functional status 2 weeks post‐discharge
Source of funding	Medical Research Council of Canada grant #MA8914
Notes	Respiratory rate reduced to greater extent in PCA group, but never < 10/min. Reduction in vital capacity and recovery rate similar QS = 2 (R = 1, DB = 0, W = 1)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
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	Low risk	Method of analysis not described but appears from Results that all participants were included in the analyses
Selective reporting (reporting bias)	Low risk	All outcomes described in Methods section are reported in Results section
Other bias	High risk	Very small sample size