Jakobsen 1986.

Methods	RCT, parallel design
Participants	Total number of randomized participants: 20 Inclusion criteria: scheduled for middle ear or nasal septum surgery, without evidence of cardiopulmonary disease Exclusion criteria: not reported Type of surgery: middle ear or nasal septum surgery Baseline characteristics Intervention group (metoprolol) Age, mean (SD): 29.4 (± 3.8) years Control group (placebo) Age, mean (SD): 36.4 (± 3.4) years Country: Denmark Setting: single centre; hospital
Interventions	Intervention group (metoprolol) Randomized, n = 10; losses = 1 (due to protocol violation with premedication); analysed, n = 9 (ITT analysis was not used) Details: metoprolol 50 mg given orally the day before surgery, then 100 mg given with premedication before anaesthesia Control group (placebo) Randomized, n = 10; losses = 0; analysed, n = 10 Details: placebo given same as the intervention
Outcomes	Outcomes measured/reported by study authors: doses and concentration of anaesthetic agents; haemodynamic variables; blood loss; recovery times; PONV, and other side effects in the PACU Outcomes relevant to the review: bradycardia (see notes)
Notes	Funding/declarations of interest: study drugs provided by Hässle, Denmark Study dates: not reported Note: study authors reported that "some patients receiving metoprolol developed a relative bradycardia before the induction of anaesthesia". Because number of events were not reported, we could not use these data in analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Use of an envelope system to randomize participants. Insufficient information
Allocation concealment (selection bias)	Unclear risk	Not specified
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Anaesthetists and surgeons were unaware of group allocation
Blinding of outcome assessors (detection bias) All outcomes	Low risk	Group allocation was concealed until after study results were available, and therefore we assumed that outcome assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss of 1 participant because of protocol violation (with premedication)
Selective reporting (reporting bias)	Unclear risk	Study authors did not report prospective clinical trial registration or publication of a protocol. It was not feasible to effectively assess risk of reporting bias
Other bias	Low risk	Not detected