Morisco 1993.

Study characteristics
Methods	RCT with parallel design
Participants	641 adult (> 18 years) participants with NYHA III or IV heart failure 319 participants in the coenzyme Q10 group and 322 in the placebo group
Interventions	Intervention: coenzyme Q10 50 mg twice or 3 times daily Control: placebo
Outcomes	NYHA clinical status Incidence of severe cardiovascular complications (pulmonary oedema, cardiac asthma, arrhythmia) Length of hospitalisation
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated allocation
Allocation concealment (selection bias)	Unclear risk	Details about allocation concealment were not mentioned
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	37 participants dropped out in the treatment group and 41 dropped out in the placebo group
Selective reporting (reporting bias)	Unclear risk	No study protocol was available
Other bias	Low risk	No other bias was found