Ellis 1994.

Methods	Randomized controlled trial comparing clonidine versus placebo.
Participants	61 people, with a diagnosis or risk factors of coronary artery disease, who were undergoing major non‐cardiac surgery (82% vascular) Age (yr): median (IQR): clonidine group: 69 (61‐74); placebo group: 68 (63‐75). Sex: 29 men, 32 women. Exclusion criteria: chronic methyldopa or clonidine therapy, serum creatinine > 30 mg/dL, planned carotid endarterectomy surgery, planned thoracic aortic aneurysm surgery, pulse < 50 bpm, or PR interval > 0.24 sec.
Interventions	Clonidine transdermal patch 200 μg/day for 72 hr from night before surgery. In addition, clonidine 300 μg orally 60‐90 min before surgery. Placebo skin patches and tablets were administered in an identical protocol.
Outcomes	All‐cause mortality (7 days). MI (persistent new Q‐wave on ECG, or CK‐MB > 40 IU) (7 days). Myocardial ischaemia (ST depression > 0.1 mV or elevation > 0.2 mV for > 1 min). Heart failure.
Notes	Study was terminated early at 61 participants due to low incidence of ischaemia. It was originally designed to recruit 160 participants in 2 arms. Funding: Anesthesiology Young Investigator Award from the Foundation for Anesthesia Education and Research. Declaration of interest: not stated. Recruitment dates: November 1990 to May 1992.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Authors reported use of computer‐generated random numbers.
Allocation concealment (selection bias)	Low risk	Sealed envelopes.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Authors reported that all participants and clinicians were blinded to treatment assignment throughout study.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessment by an investigator not involved in care of participant, blinded to allocation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All data reported.
Selective reporting (reporting bias)	Low risk	Outcomes reported were concordant with methods.
Other bias	High risk	Study terminated early because of a lower than expected rate of myocardial ischaemia; unclear whether this unblinded interim analysis was prespecified.