Comparison with other studies
In the recent systematic review by Wegner et al.,3 the
lack of rigorous clinical trials on Betahistine for primary tinnitus was
evident, including only five studies. Also, it was not possible to prove
the efficacy of this treatment (305 participants) as all studies had
methodological flaws such as non-standardized outcome measures,
heterogeneous dosages, unrepresentative samples, weak randomization, and
unreliable blinding. Thus, the quality of evidence ranged from moderate
to very low, making the results inconclusive.3
An alternative reference source of clinical trials using betahistine for
tinnitus is studies pertaining to Ménière disease6. A
recent systematic review failed to prove the efficacy of betahistine for
Ménière symptoms such as tinnitus, also been represented by poor quality
trials6. Although, unlike primary tinnitus studies,
Adrion et al.18 conducted a multicentric high-quality
trial testing low dose (2 x 24 mg daily) and high dose (3 x 48 mg daily)
betahistine against placebo, giving more confidence to betahistine
inefficacy. However, the extrapolation of these results for primary
tinnitus is limited by possible differences in the pathophysiology of
these conditions3.
In contrast to previous trials, Ganança et al.10conducted a case-control study of patients with tinnitus and vestibular
symptoms showing beneficial effects of betahistine in cases as opposed
to controls who received no treatment (32.5% vs. 17.1%). Its large
sample was an advantage over the Wegner et al.3systematic review (865 vs. 305), but the poor control of bias of
observational design compromised a valid conclusion of betahistine
efficacy.