Objective: It remains unclear whether sleep apnea (SA) is associated with tinnitus in adults. Based on a systematic review and meta-analysis of observational studies, we investigated the association between SA and tinnitus in adult population. Methods: Observational studies relevant to our research were identified by searching PubMed, Embase, Web of Science, Wanfang, and China National Knowledge Infrastructure databases. Random-effects models were used when significant heterogeneity was observed; otherwise, fixed-effects models were used. Results: Eight case-control or cross-sectional studies, including 132,292 adults were included, and 1556 of them had SA. It was shown that SA was related to a higher prevalence of tinnitus (odds ratio [OR]: 1.65, 95% confidence interval: 1.14-2.39, P < .001) with moderate heterogeneity (P for Cochrane Q test = 0.04, I2 = 53%). Seven studies reported the association between obstructive SA and tinnitus, while the other one study reported the association between overall SA and tinnitus. Subgroup analyses showed that the association was not significant for mild (OR: 1.80, P = .17) or moderate (OR: 1.25, P = .53), but significant for severe SA (OR: 2.25, P = .008). In addition, the association between SA and tinnitus seemed to be stronger in studies from Italy or United States as compared to those from China (OR: 2.91 vs 1.35, P for subgroup difference = .02). The association was not significantly affected by study design, mean age, proportion of men, methods for diagnosis of SA, and controlling of age and sex (P for subgroup difference all > .05). Conclusion: Severe SA may be related to tinnitus in adults.
Keywords: meta-analysis; observational studies; risk factor; sleep apnea; tinnitus.