EHDN.

Methods	144‐week double‐blind, unbalanced parallel study (treatment:placebo ‐ 2:1). Method of randomisation: computer generated stratification by centre. Results presented for each arm of the trial. Intention‐to‐treat and per‐protocol data analysis. Location: 44 centres (Europe).
Participants	537 patients with 158 drop‐outs. 271 male and 266 female patients. Mean age of participants: 45,5±9.7 years. Mean duration of disease: 5,5±4.4 years. Inclusion criteria: adult (25‐65 years old), genetically established HD, independently ambulatory with a TFC‐UHDRS≥8, total motor score‐UHDRS≥5, monitor compliance, caregiver to witness consent. Exclusion criteria: comorbid or co‐medication that would interfere study results, pregnancy, breast‐feeding, inadequate contraception, prior exposure to riluzole, contraindication to riluzole, serum markers of hepatic function>2xULN (alanine aminotransferase, aspartate aminotransferase and bilirubin) and anti‐choreic medication within 1 month of baseline visit.
Interventions	Oral Riluzole 100 mg/day (357 patients) and placebo ‐ identical pills ‐ (180 patients). No titration.
Outcomes	Primary: composite score of TMS‐UHDRS and TFC‐UHDRS. Secondary: TMS‐UHDRS. TFC‐UHDRS. UHDRS items: chorea score, cognitive, behavioral, functional, independence and global clinical impression subscales. Beck Depression inventory.
Notes	Negative for efficacy measures.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Low risk	A ‐ Adequate