Real-world evaluation of asthma reliever therapy among continuous users of asthma maintenance medication in Japan: A retrospective cohort study using a claims database

The decrease in mortality rate owing to asthma has slowed in recent years. A large proportion of patients with asthma remain uncontrolled in Japan. This study aimed to determine the prevalence of short-acting beta 2 agonists (SABA) overuse and its associated factors.

This large-scale retrospective cohort study analyzed continuously treated patients with asthma aged 15-74 years between January 2017 and December 2017 using a Japanese insurance claims database. Characteristics, disease information, and prescribed drugs were extracted from the database, and treatment steps were defined according to drug combinations based on the criteria of the Japanese asthma guidelines. SABA overuse was defined as ≥3 canisters per year. Factors associated with SABA overuse were estimated using multivariable logistic regression.

Among 7,483 patients with mild-to-moderate asthma, 7,001 (93.6%) and 482 (6.4%) had low and high SABA use, respectively. Inhaled corticosteroids (ICS)/long-acting β-agonists (LABA) were the main asthma control treatments. The proportions of patients who overused SABA were 347 (9.9%) and 1,201 (5.6%) in the ICS and ICS/LABA groups, respectively. The factors associated with SABA overuse were male sex, ICS monotherapy, higher treatment steps, no history of allergic rhinitis, no history of chronic sinusitis, and no asthma management.

There is a relatively low prevalence of SABA overuse among asthmatic patients in Japan. ICS/LABA therapy, treatment steps, allergic rhinitis, chronic sinusitis, and asthma management are associated with a decreased risk of SABA overuse. Further studies are needed to investigate the association between SABA overuse and asthma exacerbation and mortality.