Association Between Olfactory Function and Asthma in Adults

Chronic rhinosinusitis (CRS) and allergic rhinitis (AR) are common asthma-associated upper airway diseases. Olfactory dysfunction, a common symptom among these patients, is an increasingly recognized condition that is associated with a reduced quality of life and major health outcomes. However, there are few studies on the association between olfactory function and asthma. We investigated the relationship between asthma and olfactory function. A total of 146 patients with asthma aged >18 years were retrospectively analyzed from August 2019 to February 2020. Olfactory function was assessed using the Sniffin' stick test or the YSK olfactory function test. We compared the clinical parameters of patients with olfactory dysfunction and patients with normosmia. Of the total participants, 68 (46.6%) showed olfactory dysfunction (hyposmia, n=31; anosmia, n=37). The patients with olfactory dysfunction were older, had longer durations of asthma, and a higher proportion of those with poor general health, CRS, and nasal polyps compared to patients with normosmia. However, there were no significant differences in the socioeconomic status, lung function, asthma severity, and use of inhaled corticosteroids or intranasal steroids between the two groups. Age (odds ratio: 1.044, 95% confidence interval: 1.009-1.081, =0.012), poor general health (3.304, 1.231-8.863, =0.018), CRS (2.589, 1.155-5.804, =0.021), and nasal polyps (3.306, 1.1-9.94, =0.033) were significantly associated with olfactory dysfunction. Olfactory dysfunction was quite frequently observed in adults with asthma. Age, poor general health, CRS, and nasal polyps were significantly associated with olfactory dysfunction.