Louisa Murdin, Kiran Hussain, Anne GM Schilder

Vertigo is a symptom in which individuals experience a false sensation of movement. This type of dizziness is thought to originate in the inner ear labyrinth or its neural connections. It is a commonly experienced symptom and can cause significant problems with carrying out normal activities. Betahistine is a drug that may work by improving blood flow to the inner ear. This review examines whether betahistine is more effective than a placebo at treating symptoms of vertigo from different causes. To assess the effects of betahistine in patients with symptoms of vertigo from different causes. The Cochrane ENT Information Specialist searched the Cochrane ENT Trials Register; Central Register of Controlled Trials (CENTRAL 2015, Issue 8); PubMed; EMBASE; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. We also contacted manufacturers and researchers in the field. The date of the search was 21 September 2015. We included randomised controlled trials of betahistine versus placebo in patients of any age with vertigo from any neurotological diagnosis in any settings. We used the standard methodological procedures expected by Cochrane. Our primary outcome was the proportion of patients with reduction in vertigo symptoms (considering together the intensity, frequency and duration those symptoms). We included 17 studies, with a total of 1025 participants; 12 studies were published (567 patients) and five were unpublished (458 patients). Sixteen studies including 953 people compared betahistine with placebo. All studies with analysable data lasted three months or less. The majority were at high risk of bias, but in some the risk of bias was unclear. One study, at high risk of bias, included 72 people with benign paroxysmal positional vertigo (BPPV) and compared betahistine with placebo; all patients also had particle repositioning manoeuvres. The studies varied considerably in terms of types of participants, their diagnoses, the dose of betahistine and the length of time it was taken for, the study methods and the way any improvement in vertigo symptoms was measured. Using the GRADE system, we judged the quality of evidence overall to be low for two outcomes (proportion of patients with improvement and proportion with adverse events).Pooled data showed that the proportion of patients reporting an overall reduction in their vertigo symptoms was higher in the group treated with betahistine than the placebo group: risk ratio (RR) 1.30, 95% confidence interval (CI) 1.05 to 1.60; 606 participants; 11 studies). This result should be interpreted with caution as the test for statistical heterogeneity as measured by the I(2) value was high.Adverse effects (mostly gastrointestinal symptoms and headache) were common but medically serious events in the study were rare and isolated: there was no difference in the frequency of adverse effects between the betahistine and placebo groups, where the rates were 16% and 15% respectively (weighted values, RR 1.03, 95% CI 0.76 to 1.40; 819 participants; 12 studies).Sixteen per cent of patients from both the betahistine and the placebo groups withdrew (dropped out) from the studies (RR 0.96, 95% CI 0.65 to 1.42; 481 participants; eight studies).Three studies looked at objective vestibular function tests as an outcome; the numbers of participants were small, techniques of measurement very diverse and reporting details sparse, so analysis of this outcome was inconclusive.We looked for information on generic quality of life and falls, but none of the studies reported on these outcomes. Low quality evidence suggests that in patients suffering from vertigo from different causes there may be a positive effect of betahistine in terms of reduction in vertigo symptoms. Betahistine is generally well tolerated with a low risk of adverse events. Future research into the management of vertigo symptoms needs to use more rigorous methodology and include outcomes that matter to patients and their families.