BACKGROUND:Possible variation in bronchodilator response (BDR) according to age at the diagnosis of adult-onset asthma is unknown. Our aim was to assess if BDR in FEV 1 is related to age at diagnosis of adult-onset asthma and how many subjects fulfill the 400?mL criterion of BDR, the suggested cut-off for asthma-like reversibility in asthma-COPD overlap (ACO).METHODS:A total of 1030 patients with adult-onset asthma were included; 245 from SAAS (Sein?joki Adult Asthma Study, Finland) and 785 from COREA (Cohort for Reality and Evolution of Adult Asthma in Korea) cohorts. BDR in FEV 1 at the diagnosis of asthma was assessed. Patients were divided into groups based on age at asthma diagnosis: ?40, 40-59.9, and?≥?60?years. The cohorts were analyzed separately.RESULTS:BDR % in FEV 1 did not differ between the groups of different age at asthma diagnosis and no correlation between BDR and age was found. Of patients aged ≥40?years, only 18% (SAAS-cohort) and 5% (COREA-cohort) reached the 400?mL BDR in FEV 1 . After exclusion of possible ACO patients, the results remained similar.CONCLUSION:By using two large cohorts of steroid-naive patients with asthma, we have shown that BDR at diagnosis of asthma is constant over large age span range, and the limit of 400?mL in BDR in FEV 1 is rarely reached.TRIAL REGISTRATION:Sein?joki Adult Asthma Study is registered at ClinicalTrials.gov with identifier number NCT02733016 .
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