The Impact of COVID-19 on Hay Fever Treatment in Japan: A Retrospective Cohort Study Based on the Japanese Claims Database

Background: Hay fever (HF) presents with various symptoms, including allergic conjunctivitis and rhinitis, and requires cross-organ treatment. This study assessed the impact of the coronavirus disease 2019 (COVID-19) pandemic on HF treatment trends.

Methods: This retrospective cohort study utilized data from the JMDC database collected between January 2018 and May 2021. Patients with HF were identified based on the relevant International Classification of Diseases 10th Revision diagnosis codes and the prescription of HF-related medications. The treatment approaches were compared during the cedar and cypress pollen allergy season (January to May in Japan) before and during the COVID-19 pandemic (2018 and 2019, and 2020 and 2021, respectively).

Results: This study included 2,598,178 patients with HF. The numbers of prescribed HF-related claims in 2018, 2019, 2020, and 2021 were 3,332,854, 3,534,198, 2,774,380, and 2,786,681 times, respectively. Oral second-generation antihistamine prescriptions decreased by >10% from 2019 to 2020, with a <10% change in the subsequent year. Anti-allergic eye drop prescriptions also decreased by >10% from 2019 to 2020 but increased by >10% from 2020 to 2021. Compared with 2018, 2019, and 2020, the number of claims in the rhinitis symptoms dominant group was significantly decreased in 2021 (p < 0.001, all). In contrast, the number of claims in the eye symptoms dominant group and the rhinitis and eye symptoms dominant group increased in 2021 compared with that in 2018, 2019, and 2020 (p < 0.001, all).

Conclusion: Changes in HF treatment and related outcomes could be attributed to lifestyle modifications resulting from the COVID-19 pandemic. Measures, such as limiting outdoor activities and adopting mask-wearing practices may have influenced HF symptoms, preventive behaviors, and the overall approach to treating HF.