Limited evidence for the effect of sodium fluoride on deterioration of hearing loss in patients with otosclerosis: a systematic review of the literature.

Objective: To determine the protective effect of sodium fluoride on the deterioration of hearing loss in adult patients with otosclerosis.

Data Sources: PubMed, Embase, the Cochrane Library, and CINAHL.

Study Selection: A systematic literature search was conducted. Studies reporting original study data on the deterioration of hearing loss in otosclerosis patients treated with sodium fluoride were included.

Data Extraction: Directness of evidence (DoE) and risk of bias (RoB), using the Cochrane Collaboration's tool for assessing risk of bias, of the selected articles were assessed. Studies with low DoE, high RoB, or both were excluded. Absolute risks, mean deterioration of hearing in decibels, risk differences, and their 95% confidence intervals were extracted from the included studies.

Data Synthesis: Our search yielded 168 original titles, of which, 2 placebo-controlled studies were eligible for data extraction. The results of these 2 studies were conflicting. One of the included studies, with high DoE and moderate RoB, reported an absolute risk reduction for deterioration of hearing loss of 18% [95% CI 17; 19] when treating with sodium fluoride. The other included study, with high DoE and moderate RoB, reported no clinically significant difference in mean deterioration of bone-conduction, air-conduction, or air-bone gap between the sodium fluoride group and the placebo group.

Conclusion: There is weak evidence from one study with significant limitations that deterioration of hearing loss in otosclerosis patients receiving sodium fluoride treatment is less than in patients treated with a placebo.