Summary of findings for the main comparison. Betahistine compared with placebo for tinnitus.
| Betahistine compared with placebo for tinnitus (without concurrent medication) | ||||||
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Patient or population: patients with subjective idiopathic tinnitus Settings: departments of otorhinolaryngology in hospitals worldwide Intervention: betahistine Comparison: placebo | ||||||
| Outcomes | Treatment effects | Relative effect (95% CI) | No of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Placebo | Betahistine | |||||
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Tinnitus loudness measured by a visual analogue scale (range 0 to 10/more than 10) Follow‐up: 1 month |
The mean tinnitus loudness ranged across control groups from 4.8 to 8.5 | The mean tinnitus loudness in the intervention groups was 0.2 lower (0.3 lower to 1.0 higher) | ‐0.16 (‐1.01 to 0.70) | 81 (2) | ⊕⊝⊝⊝ very low1 | — |
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Change in tinnitus loudness measured by a visual analogue scale (range 0 to more than 10) Follow‐up: 28 days |
The mean change in tinnitus loudness was 0.8 in the control group | The mean change in tinnitus loudness in the intervention group was 0.4 lower | ‐0.43 (‐1.20 to 0.34) | 11 (1) | ⊕⊝⊝⊝ very low2 | — |
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Tinnitus loudness measured by a visual analogue scale (range 0 to 10) Follow‐up: 2 months |
The mean tinnitus loudness was 4.5 in the control group | The mean tinnitus loudness in the intervention group was 0.4 lower | ‐0.39 (‐1.37 to 0.60) | 70 (1) | ⊕⊝⊝⊝ very low3 | — |
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Significant adverse effects (yes or no) Follow‐up: 28 days |
Study population | Not estimable | 11 (1) | ⊕⊝⊝⊝ very low2 | — | |
| 0 per 1000 | 0 per 1000 | |||||
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Significant adverse effects (yes or no) Follow‐up: 3 months |
Study population | Not estimable | 41 (1) | ⊕⊕⊕⊝ moderate4 | — | |
| 0 per 1000 | 0 per 1000 | |||||
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Change in Tinnitus Severity Index (range 0 to 56) Follow‐up: 12 weeks |
The mean change in Tinnitus Severity Index was 1.7 in the control group | The mean change in Tinnitus Severity Index in the intervention group was the same | 0.02 (‐1.05 to 1.09) | 50 (1) | ⊕⊕⊕⊝ moderate4 | — |
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Tinnitus severity score (range 0 to 4) Follow‐up: 3 months |
The mean tinnitus severity score was 3.1 in the control group | The mean tinnitus severity score in the intervention group was 0.5 lower | ‐0.52 (‐1.34 to 0.30) | 36 (1) | ⊕⊕⊝⊝ low5 | |
| Depressive symptoms | Not measured | |||||
| Symptoms of generalised anxiety | Not measured | |||||
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Other adverse effects (yes or no) Follow‐up: 28 days |
Study population | RR 3.50 (0.17 to 70.94) | 11 (1) | ⊕⊝⊝⊝ very low2 | — | |
| 0 per 1000 | 200 per 1000 | |||||
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Other adverse effects (yes or no) Follow‐up: 3 months |
Study population | Not estimable | 41 (1) | ⊕⊕⊕⊝ moderate4 | — | |
| 0 per 1000 | 0 per 1000 | |||||
| CI: confidence interval; RR: risk ratio | ||||||
| GRADE Working Group grades of evidence High‐quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate‐quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low‐quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low‐quality: We are very uncertain about the estimate. | ||||||
1Downgraded one level due to an unclear overall risk of bias in both studies; downgraded one level due to inconsistency (one study has a slight preference for betahistine and the other for placebo); downgraded one level due to indirectness (in one study a patient with Ménière's disease was included and in the other studies only male participants/military personnel with noise‐induced hearing loss were included); downgraded one level due to imprecision.
2Downgraded one level due to an unclear overall risk of bias, downgraded one level due to indirectness (a patient with Ménière's disease was included); downgraded one level due to imprecision.
3Downgraded one level due to an unclear overall risk of bias, downgraded one level due to indirectness (only male participants/military personnel with noise‐induced hearing loss were included); downgraded one level due to imprecision.
4Downgraded one level due to an unclear overall risk of bias.
5Downgraded one level due to an unclear overall risk of bias; downgraded one level due to imprecision.