Impact of airflow obstruction on long-term mortality in patients with asthma in Japan

Background: The long-term prognosis of asthma with airflow obstruction is poorly understood in Japan. The aim of this retrospective 26-year study was to investigate the long-term mortality risk of airflow obstruction in asthmatics. Methods: Using data from the Omuta City Air Pollution-related Health Damage Cohort Program, mortality risk ratios of airflow obstruction in Japanese Individuals were analyzed by Cox proportional hazards models. Airflow obstruction was considered to be present when the forced expiratory volume in 1 sec (FEV1)/forced vital capacity ratio was