Berman 2004.

Study characteristics
Methods	RCT with parallel design
Participants	32 participants with end‐stage heart failure awaiting heart transplantation were randomly allocated to receive 60 mg U/day of ultrasome coenzyme Q10 or placebo for 3 months Adults (> 18 years) All participants continued their regular medication regimen
Interventions	Intervention: oral coenzyme Q10 60 mg daily Control: placebo
Outcomes	Symptoms improvement (NYHA classification) Symptoms improvement measured on the Minnesota Living with Heart Failure Questionnaire Quality of life on 6‐minute walk test Blood tests for atrial natriuretic peptide and tumor necrosis factor Echocardiography
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised, no details about random sequence generation
Allocation concealment (selection bias)	Low risk	Group allocation was done by a third (external) party. Participants were given a personal addressed, sealed envelope containing the words "code A" or "code B"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information given
Incomplete outcome data (attrition bias) All outcomes	High risk	5 participants failed to complete the study because of death, need for heart transplantation, drug‐induced intestinal upset, inconvenient travel connections and lack of compliance (1 participant each). Study also did not report the number of participants in the treatment and placebo groups
Selective reporting (reporting bias)	Unclear risk	No study protocol was available.
Other bias	Low risk	No other bias could be found