Kocharian 2009.

Study characteristics
Methods	RCT with parallel design
Participants	38 participants younger than 18 years with idiopathic dilated cardiomyopathy were assigned to receive either coenzyme Q10 or placebo for a period of 6 months 17 participants in the coenzyme Q10 group and 21 in the placebo group Children (< 18 years)
Interventions	Intervention: oral coenzyme Q10 2 mg/kg/day in 2 or 3 divided doses, these being increased to the maximum dose of 10 mg/kg/day according to tolerance or the appearance of side effects Control: placebo
Outcomes	Left ventricular ejection fraction
Notes	This is the only study that evaluated the use of coenzyme Q10 in children
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised, no details about random sequence generation provided.
Allocation concealment (selection bias)	Unclear risk	No information given
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants completed the trial
Selective reporting (reporting bias)	Low risk	All outcomes listed in the protocol were reported in the manuscript.
Other bias	Low risk	No other bias could be found