RT Journal Article SR Electronic T1 Mechanism by which inhaled bronchodilators prevent exacerbations in chronic obstructive pulmonary disease JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P694 VO 42 IS Suppl 57 A1 Worawan Sirichana A1 Chi-Hong Tseng A1 Igor Barjaktarevic A1 Eric C. Kleerup A1 Christopher B. Cooper YR 2013 UL http://erj.ersjournals.com/content/42/Suppl_57/P694.abstract AB IntroductionLarge-clinical trials show that various medications decrease exacerbation frequency (E) in chronic obstructive pulmonary disease (COPD). The mechanism is not understood but could relate to symptom relief (reducing exacerbation reporting), improved airway patency (promoting clearance of secretions and reduced bacterial colonization) or a true anti-inflammatory action of the bronchodilator therapy.Aims and ObjectivesWe examined the hypothesis that improved airway patency is responsible for reducing E by studying the relationship between the risk reduction for exacerbations and changes in forced expiratory volume in one second (dFEV1) during published clinical trials.MethodsWe included 10 COPD clinical trials and used meta-regression analysis to calculate the overall association between risk reduction for exacerbations and dFEV1 (where dFEV1 between parallel groups was calculated by adding differences at randomization plus those due to treatment).ResultsAltogether, 22,280 subjects were included in the analysis representing 52,031 years of patient observation. Mean E was 1.29 (0.73-2.41) /patient-year and mean FEV1 was 44.1%. The data estimate an increase in FEV1 of 100 ml is associated with a risk reduction for exacerbations of 0.31 /patient-year (SE 0.075, p=0.00004).ConclusionsUsing meta-regression analysis of 10 clinical trials in COPD, a significant correlation was found between changes in FEV1 and decreased exacerbation rate. These findings support the hypothesis that improved airway patency through bronchodilatation is responsible for preventing exacerbations perhaps by improving pulmonary hygiene and reducing bacterial colonization.