Prevalence and relationship of olfactory dysfunction and tinnitus among middle-and old-aged population in Korea

Olfactory dysfunction and tinnitus are age-related otorhinolaryngological disorders with a high prevalence in the elderly population and share several common clinical features. However, there is no study investigating the relationship between these two diseases. We studied the prevalence of olfactory dysfunction and tinnitus among Koreans and studied the relationship between these two diseases based on the Korean National Health and Nutrition Examination Survey. The subjects of this study were enrolled from the Fifth Korean National Health and Nutrition Examination Survey (2010-2012, n = 25,534). Data of subjects aged 40 years and older who underwent physical examination and completed a self-reported questionnaire and other anthropometric variables were statistically analyzed. Odds ratios were calculated to identify the relationship between olfactory dysfunction and tinnitus, using multiple logistic regression models. Older males, non-smokers, non/lower alcohol drinker groups exhibited the relationship between olfactory dysfunction and tinnitus. Metabolic syndrome and mental health problems were associated with both olfactory dysfunction and tinnitus. After adjusting for confounding factors, olfactory dysfunction was significantly associated with tinnitus (OR 1.318). There was a dose-response relationship between tinnitus severity and the odds of olfactory dysfunction (ORs for mild, moderate and severe tinnitus were, respectively, 1.134, 1.569 and 2.044). Additional molecular genetics and animal studies are needed to determine the shared pathophysiology of the two diseases.