The Influence of Obstructive Sleep Apnea and Nasal Continuous Positive Airway Pressure Therapy on Olfactory Function

OBJECTIVE: To investigate the association between clinical sleep parameters and olfactory function (OF) in patients with obstructive sleep apnea (OSA) and to evaluate the therapeutic effect of 12-month continuous positive airway pressure (CPAP) on olfactory dysfunction (OD). METHODS: A total of 146 participants were included: 55 healthy controls, 68 untreated OSA patients, and 23 CPAP-treated patients. OSA severity was classified according to the apnea-hypopnea index (AHI). OF was assessed using the Sniffin' Sticks test. Clinical variables, sleep parameters, and olfactory scores were compared among groups. Subgroup analysis between CPAP-treated and untreated OSA patients used the Mann-Whitney U test. Multivariate logistic regression identified predictors of olfactory improvement. RESULTS: < .001). After 12 months of CPAP treatment, the mean olfactory score reached 13.87 ± 1.96, significantly higher than 9.78 ± 4.217 in the untreated group, demonstrating substantial functional recovery. CONCLUSION: The results indicated a close relationship between OD and disease severity in patients with OSA and confirmed that long-term CPAP therapy can effectively improve OF. These findings provide new insights into the multisystem impact of OSA and suggest that olfactory assessment may serve as a complementary clinical tool for OSA evaluation.