Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Patients consenting to enrolment were stratified by surgeon. Within strata, treatment regimens were assigned according to a randomization scheme containing variably sized, balanced blocks of treatment assignments
Allocation concealment (selection bias)	Low risk	The evening before surgery, the JHH Investigational Pharmacy determined the participant's treatment assignment and prepared the masked study medications
Blinding of participants and personnel (performance bias)	Low risk	Masked study medication delivered by the pharmacy
Blinding of outcome assessment (detection bias)	Low risk	Masked study medication delivered by the pharmacy
Incomplete outcome data (attrition bias)	High risk	Eight participants (two in each group) enrolled in the pilot study; their data have been added for mortality. For MI and pneumonia, the trial authors provided the data for participants who survived until hospital discharge
Selective reporting (reporting bias)	High risk	MI and pneumonia among participants who did not survive until hospital discharge not provided. Presence/absence of complications related to the anaesthetic techniques not reported
Other bias	High risk	Half the participants in the GA group (as remodelled for this overview) received postoperative epidural analgesia