Seasonality of Sensorineural Hearing Loss and Impact of the Coronavirus Disease 2019 Pandemic

Objective This study aimed to clarify the seasonality of the incidence of sudden sensorineural hearing loss and the impact of the coronavirus disease 2019 pandemic. Study Design An interrupted time‐series design. Setting Comprehensive insurance claims data from the National Database of Health Insurance Claims and Specific Health Checkups of Japan collected between October 2013 and September 2023 were used. Methods Individuals who developed sudden sensorineural hearing loss were identified as those with disease code(s) and drug code(s) for steroids with a prior disease‐free period of 1 year. Time series data on incidence rate were created from the number of the incidence and population for each month. An interrupted time series analysis with a seasonal autoregressive integrated moving average model was performed. Results According to the model with the lowest Akaike's information criterion, the incidence of sudden sensorineural hearing loss was seasonal: more frequent in early summer and less frequent in winter. The interrupted time‐series analysis revealed a significant decrease of 1.38 cases per 100,000 people (95% confidence interval: 1.01, 1.76) each month during the pandemic and a significant temporary additional decrease of 2.07 cases per 100,000 people (95% confidence interval: 1.44, 2.70) in April and May 2020. Conclusion This population‐based study in Japan reveals seasonality in the incidence of sudden sensorineural hearing loss and a decrease during the coronavirus disease 2019 pandemic. Despite the observational nature of the study, the findings may be useful in elucidating the etiology of sudden sensorineural hearing loss.