Ranen NG.

Methods	52‐week double‐blind, parallel study. Method of randomisation: not stated. Results presented for each arm of the trial. Intention‐to‐treat data analysis. Location: 1 centre (USA).
Participants	100 patients, 9 drop‐outs. 44 male and 47 female patients (per‐protocol cohort). Mean age of participants: 42.1±11.7 years. Mean age of disease onset: 5,0±0.4 years. Inclusion criteria: mild‐moderate HD (family history, chorea/rigidity, MMSE>14), relative or companion to serve as informant and to supervise medication. Exclusion criteria: current major depression, other CNS disease, active medical illness, alcohol or substance abuse, psychosis, MRI evidence of striatal infarction. CNS‐acting medication (antipsychotics, CoQ, vitamin E, BZD, barbiturics, antioxidants, CNS‐acting antihypertensives), except stable use of nortriptyline (depression) and carbamazepine (mania or irritability), chloral hydrate up to twice a week (sleep), but not within 72h of screening/visits.
Interventions	Oral Idebenone 270 mg/day (48 patients) and placebo, identical pills (43 patients). No titration.
Outcomes	Primary: Change in the composite of ADL‐UHDRS and QNE (chorea, eye movement, motor impairment scales). Secondary: Change in cognitive function (MMSE). Change in neuropsychiatric performance (Buschke Selective Reading test, Benton Visual Retention test, Grooved Pegboard, Wechsler Adult Intelligence Scale, Trail Making test, Stroop test).
Notes	Negative for efficacy measures.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	B ‐ Unclear