Sputum Eosinophilia, Airway Hyperresponsiveness and Airway Narrowing in Young Adults with Former Asthma

Background: 30–80% of outgrown asthma subjects develop symptoms again later in life. We investigated inflammation and function of lower airway in adolescents with former asthma. Methods: 326 never-smoking young adults (mean age 24.0 years) were interviewed with special emphasis on history of asthma. Diagnosis of asthma was based on GINA guidelines. Former asthma subjects consisted of ones with a history of physician-diagnosed childhood asthma, who had been free of asthma symptoms without the use of medication for at least 10 years prior to the study. Provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second (FEV1) (PC20) and eosinophil percentage in induced sputum were measured. Results: 31 subjects were former asthma subjects (FBA), 11 subjects were current asthma subjects (CBA) and 284 subjects had no history of asthma (non-BA). PC20 and FEV1/FVC ratio were significantly lower in the FBA group than in the non-BA group (P < 0.01). Maximal mid-expiratory flow (MMF) was significantly lower in the FBA group than in the non-BA group (P < 0.05). Sputum eosinophil percentage was significantly increased in the FBA group compared with the non-BA group (P < 0.01). PC20 was significantly lower in the CBA group than in the FBA and non-BA groups (P < 0.01). FEV1, FEV1/FVC ratio and MMF were significantly lower in the CBA group than in the FBA group (P < 0.05, P < 0.05 and P < 0.05, respectively) and the non-BA group (P < 0.01, P < 0.01 and P < 0.05, respectively). Sputum eosinophils were significantly higher in the CBA group than in the FBA and non-BA groups (P < 0.01). Conclusions: This study shows that subjects with long-term outgrown asthma continue to have airway eosinophilic inflammation, airway hyperresponsiveness and airway narrowing.