Duphar H10802786F/M 1989.

Study characteristics
Methods	Allocation: randomised, but no further details Design: prospective, parallel‐group, multicentre (5 centres)
Participants	Number: 54 randomised, 38 analysed Age: mean 45.8 Gender: 20 M, 34 F Setting: 5 centres in France Eligibility criteria: at least 2 attacks of vertigo of over 2 minutes in the past 3 months at least 2 weeks apart; vertigo with and without cochlear symptoms Exclusion criteria: other causes of vertigo, relevant medications Baseline characteristics: comparable for age, sex, duration of history and time since last attack
Interventions	Betahistine 16 mg 3 times a day versus placebo for 90 days Intervention group: n = 27 Comparator group: n = 27 Use of additional interventions: none
Outcomes	Primary outcome: severity on 6‐point ordinal scale (0 to 5) Secondary outcomes: frequency of attacks, severity of attacks, investigator global assessment
Funding sources	Manufacturer unpublished data
Declarations of interest	Manufacturer unpublished data
Notes	Unpublished study ‐ manufacturer supplied data
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation in blocks of 4, but sequence generation method unclear
Allocation concealment (selection bias)	Unclear risk	Method not stated
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind, but no further information
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Double‐blind, but no further information
Incomplete outcome data (attrition bias) All outcomes	High risk	Participants lost to follow‐up: 16. Analysis was "as treated".
Selective reporting (reporting bias)	Unclear risk	Protocol not available for inspection
Other bias	Unclear risk	—