PT - JOURNAL ARTICLE AU - W.Y. Lee AU - T. Southworth AU - D. Singh TI - A comparison of two allergen challenge methods in asthmatics using inhaled corticosteroids DP - 2013 Sep 01 TA - European Respiratory Journal PG - P3954 VI - 42 IP - Suppl 57 4099 - http://erj.ersjournals.com/content/42/Suppl_57/P3954.short 4100 - http://erj.ersjournals.com/content/42/Suppl_57/P3954.full SO - Eur Respir J2013 Sep 01; 42 AB - Rationale:The dosimeter and tidal breathing method are the two most common inhalational allergen challenge methods used in clinical trials.They have been used in inhaled corticosteroid (ICS) naïve asthmatics only.Aim:To compare these two methods in asthmatics taking ICSMethod:14 asthmatics taking ICS<1000mcg BDP equivalent were recruited (mean age:40yrs,mean FEV1% pred:89.0%,mean ICS dose:396mcg).Each patient had an allergen challenge using the dosimeter method first, then the tidal breathing method at least 2wks later.For the dosimeter method, the incremental dose challenge was used.FEV1 was measured 10hrs post allergen inhalation.Induced sputum was collected at baseline and 24hrs post allergen challenge.The early asthmatic response(EAR) is expressed as area under curve(AUC) percent change in FEV1 during first 2hrs(AUC0-2h) and maximum fall in FEV1 during this time.The late asthmatic response(LAR) is expressed as AUC percent change in FEV1 during 4-10hrs(AUC4-10h) and maximum fall in FEV1 during this time.Result:There was no significant difference in the mean maximum fall in FEV1 during the EAR and LAR(p=0.74,p=0.95 respectively), or mean EAR AUC0-2h and LAR AUC4-10h between the two methods(p=0.95,p=0.86 respectively).Bland Altman analysis indicated good agreement between both methods.There was a statistically significant rise in post allergen sputum eosinophil% count from baseline after the dosimeter and tidal breathing method(p=0.010,p=0.004 respectively).Conclusion:The dosimeter and tidal breathing method show high degree of comparability and both methods induce an allergic inflammatory response in asthmatics on ICS.Both methods can be used in clinical trials to study drug effects.