Summary of findings 1. Betahistine versus placebo for symptoms of vertigo.
| Betahistine versus placebo for symptoms of vertigo | ||||||
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Patient or population: patients with symptoms of vertigo
Setting: outpatient clinics
Intervention: betahistine
Comparison: placebo Time frame: up to 3 months | ||||||
| Outcomes | Relative effect (95% CI) | Anticipated absolute effects* (95% CI) | Quality of the evidence (GRADE) | What happens | ||
| Without betahistine | With betahistine | Difference | ||||
| Benefits | ||||||
| Proportion of patients with improvement according to global judgement of patient subgrouped by diagnosis № of participants: 606 (11 RCTs) | RR 1.30 (1.05 to 1.60) | Moderate | ⊕⊕⊝⊝ LOW 1 2 3 | If 100 patients with vertigo are treated with betahistine, 60 will improve. This is 14 more than would have improved if a sham medicine had been taken instead of betahistine. | ||
| 46.2% | 60.1% (48.5 to 73.9) | 13.9% more (2.3 more to 27.7 more) | ||||
| Harms | ||||||
| Proportion of patients with adverse effects № of participants: 819 (12 RCTs) | RR 1.03 (0.76 to 1.40) | Moderate | ⊕⊕⊝⊝ LOW 2 4 | If 100 patients with vertigo are treated with betahistine, 16 will experience adverse effects. This is 1 more than would have had similar symptoms if a sham medicine had been taken instead of betahistine. | ||
| 15.2% | 15.7% (11.6 to 21.3) | 0.5% more (3.6 fewer to 6.1 more) | ||||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RCT: randomised controlled trial; RR: risk ratio | ||||||
| GRADE Working Group grades of evidence High quality: We are very confident that the true effect lies close to that of the estimate of the effect Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
1Although statistical heterogeneity (I2 statistic) was 64%, the direction of effects was consistent.
2Most evidence was from studies with serious methodological limitations (unclear sequence generation, allocation concealment and blinding).
3Non‐validated outcome measures were used to measure improvement.
4Confidence intervals were wide and crossed thresholds of important benefits and harms.