Incidence of Olfactory Dysfunction and Associated Factors: A Nationwide Cohort Study From South Korea

Hyo Jin Chung, Hyun Seon Lim, Kyuin Lee, Hyun Seung Choi, Junhui Jeong, Hyang Ae Shin, Chang Hoon Kim, Jung Hyun Chang

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Objectives: Olfactory dysfunction, a reduced or complete loss of the ability to smell, is gaining attention because of its substantial impact on an individual’s quality of life and the possibility that it is an important sign of underlying disease. However, olfactory dysfunction is underdiagnosed in the general population due to diagnostic difficulty and unpredictable prognosis. This study aimed to evaluate the prevalence of clinically diagnosed olfactory dysfunction in South Korea by using well-organized, nationwide, population-based cohort data, and the associations between olfactory dysfunction and risk of neurodegenerative disorders. Methods: We investigated the Korean National Health Insurance Service–National Sample Cohort for patients diagnosed with olfactory dysfunction according to the International Classification of Diseases. Annual and overall incidence and prevalence of olfactory dysfunction during 2003 to 2013 and patient characteristics were analyzed. Based on those identified patients who were later diagnosed with neurodegenerative disorder, hazard ratios (HRs) of sociodemographic factors and comorbidities associated with neurodegenerative disorder were evaluated using a Cox proportional hazard regression model. Results: In total, 6296 patients were clinically diagnosed with olfactory dysfunction during the study period (524.67 patients/year). The prevalence increased annually and was higher in female patients. The incidence of neurodegenerative disorders among patients with olfactory dysfunction was 4.2% within the study period. Multivariate cox regression analysis of the patients (n = 249) revealed that diabetes mellitus (HR = 1.976) and depression (HR = 2.758) were significant risk factors. Conclusions: Olfactory dysfunction is underdiagnosed in South Korea, but it is clinically important considering the possibility of presymptom of neurodegenerative disorders. In clinical practice, we should consider its association with neurodegenerative disorders and possibly other systemic conditions.

Original languageEnglish
Pages (from-to)NP499-NP505
JournalEar, Nose and Throat Journal
Issue number10
Publication statusPublished - 2023 Oct

Bibliographical note

Publisher Copyright:
© The Author(s) 2021.

All Science Journal Classification (ASJC) codes

  • Otorhinolaryngology


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