Clinical significance of smell and taste dysfunction and other related factors in COVID-19

PURPOSE: The objective of this study is to evaluate smell and taste dysfunction (STD) in coronavirus disease 2019 (COVID-19) positive and negative patients, and to assess the factors associated with STD in COVID-19 positive patients. METHODS: Patients who had been tested with the real-time reverse transcriptase-polymerase chain reaction (RT-PCR) for COVID-19 were identified, and according to the RT-PCR test results, patients were separated into Positive and Negative Groups. A telephone-based assessment was applied to both groups using the American Academy of Otolaryngology–Head and Neck Surgery Anosmia Reporting Tool. Patients in Positive Group were also asked to rate STD, nasal breathing, and anxiety in three different time periods (pre-/during-/post-COVID) using the visual analog scale (VAS). RESULTS: A total of 53 COVID-19 positive and 51 negative patients completed the surveys. STD was eightfold more frequent (OR 8.19; CI 95% 3.22–20.84) in the Positive Group. Of the 53 COVID-19 positive patients, 32 reported STD and 21 did not. ‘Ground-glass appearance’ on chest-computed tomography was more frequent and median lymphocyte count was significantly lower in COVID-19 positive patients with STD. During-COVID STD and nasal breathing VAS scores were significantly lower than the pre- and post-COVID scores. During-COVID STD scores were significantly correlated with anxiety scores (Spearman’s rho-0.404, p = 0.022) but not correlated with nasal breathing scores. CONCLUSION: STD may be related to increased inflammatory response as well as damage of olfactory neuronal pathway or non-neuronal olfactory mucosa. Understanding the exact cause of chemosensory impairment in COVID-19 can be helpful in explaining the pathophysiology of the disease. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00405-020-06503-9) contains supplementary material, which is available to authorized users.