Five-year trends in inhalation therapy for asthma: A single-center retrospective cohort study

Abstract

Inhalation therapy is the primary treatment modality for asthma. Numerous inhaled formulations are available in different combinations of medications and devices. However, the appropriate inhalers for specific patient populations have not been clarified. This study aimed to investigate the 5-year trend in inhalation therapy for asthma in Japan. This retrospective study evaluated patients with asthma who regularly visited our clinic between January 2018 and December 2023. The patients were stratified by asthma treatment step, and the content of inhalation therapy and patient characteristics in 2018, 2021, and 2023 were investigated. Overall, 243 patients underwent inhalation therapy. In 2023, 64.2％ were female, and the mean age was 62.8±15.8 years. Dry powder inhalers （DPIs） were used more frequently than were pressurized metered-dose inhalers （pMDIs） in all treatment steps in all years. The use of pMDIs increased from 16.4％ in 2018 to 21.6％ in 2021 but decreased to 18.1％ in 2023. For inhaled medications, the combination of inhaled corticosteroid （ICS）/long-acting β2-receptor agonist （LABA） was the most frequently used. However, the number of patients using ICS/LABA significantly decreased in 2023 relative to that in 2021, whereas the number of patients using single-inhaler triple therapy （SITT） significantly increased. Although DPIs are used more frequently, certain patients require pMDIs, and it may be more useful for them. The approval of SITT has improved accessibility to long-acting muscarinic receptor antagonists. This study emphasizes the importance of understanding inhaler types and medication characteristics to enable personalized treatment based on each patient’s needs.