Mitchell 2003.

Methods	RCT, parallel design
Participants	141 adult participants Elective procedures for atrial arrhythmias ASA status not given Hospital, UK
Interventions	Midazolam (2 mg/kg undiluted iv bolus of 5 mg with further aliquots of 1‐2 mg each minute up to maximum dose of 30 mg) Diazepam (5‐10 mg iv bolus followed by aliquots of 5‐10 mg each minute to maximum dose of 70 mg) Both groups given additional analgesics if required (such as diamorphine, morphine and pethidine) Aim: "Adequate sedation was determined by loss of response to verbal stimulus or tactile stimulus"
Outcomes	Hypotension Mortality Patient awareness/recall Success of cardioversion Time to loss of consciousness Time to awakening Need for additional analgesics
Results	Midazolam vs Diazepam Hypotension: 14/71 vs 5/70 Recall at 24 hours: 0/71 vs 1/70 Mortality: 0/71 vs 0/70 Successful cardioversion: 63/71 vs 61/70 Additional analgesics: 0/71 vs 4/70 Patient satisfaction: 70/71 vs 64/70
Notes	Anaesthetic administered by attending doctor (anaesthetist available within 5 minutes). This is no longer standard practice in UK
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomized but no further details
Allocation concealment (selection bias)	Unclear risk	No details
Blinding of participants and personnel (performance bias) Major adverse events	High risk	Attending doctor who administered anaesthetic was aware of drug allocation
Blinding of participants and personnel (performance bias) Mortality	High risk	Attending doctor who administered anaesthetic was aware of drug allocation
Blinding of participants and personnel (performance bias) Patient reported outcomes (recall/satisfaction)	High risk	Attending doctor who administered anaesthetic was aware of drug allocation
Blinding of participants and personnel (performance bias) Success of cardioversion	Unclear risk	Attending doctor who administered anaesthetic was aware of drug allocation
Blinding of participants and personnel (performance bias) Minor adverse events	High risk	Attending doctor who administered anaesthetic was aware of drug allocation
Blinding of participants and personnel (performance bias) Time to induction etc/need for resedation.	High risk	Attending doctor who administered anaesthetic was aware of drug allocation
Blinding of outcome assessment (detection bias) Major adverse event	Unclear risk	No details as to who recorded all outcome assessments
Blinding of outcome assessment (detection bias) Mortality	Unclear risk	No details as to who recorded all outcome assessments. Assume not blinded
Blinding of outcome assessment (detection bias) Patient reported outcomes (recall/satisfaction)	Low risk	Participant blinded to study allocation
Blinding of outcome assessment (detection bias) Success of cardioversion	Unclear risk	No details as to who recorded all outcome assessments. Assume not blinded
Blinding of outcome assessment (detection bias) Minor adverse events	Unclear risk	No details as to who recorded all outcome assessments. Assume not blinded
Blinding of outcome assessment (detection bias) Time to induction etc./need for resedation	Unclear risk	No details as to who recorded all outcome assessments. Assume not blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	15 participants (11 in midazolam group; 4 in diazepam group) given flumazenil and excluded from awakening data
Selective reporting (reporting bias)	Unclear risk	Outcomes from methods appear to be reported  Prepublished protocol not sought
Other bias	Unclear risk	No details presented for all baseline characteristics – although described as comparable