Pragmatic evaluation of inhaled corticosteroid particle size formulations on asthma control

Background: Extra-fine particle formulations of inhaled corticosteroid (ICS) are associated with improved lung delivery. Objectives: A pragmatic study to assess patient-reported outcomes after switching from fine to extra-fine particle ICS in persistent asthma. Methods: Twenty-four patients (mean age 48 year, FEV ₁ 84%, ACQ 1.67) received 4 weeks run-in with a constant dose of fine particle ICS (mean dose 710 µg), followed by switching to an equivalent dose of extra-fine particle hydrofluoroalkane beclomethasone dipropionate (mean dose 355µg). Asthma control questionnaire (ACQ), the primary outcome and mini asthma quality of life questionnaire (mAQLQ) were measured pre- and post-run-in (baseline) and after 4 weeks and 8 weeks of switching. Results: Comparing pre- vs post-run-in, there were no differences for ACQ: 1.67 vs 1.65 or AQLQ: 5.08 vs 5.34. There were mean (95%CI) improvements (P < 0.001) from baseline after 8 weeks for ACQ: −0.53 (−0.83, −0.23) and AQLQ: 0.69 (0.35, 1.04), which exceeded the minimal clinically important difference (MCID) of 0.5 for both. There were also differences (P < 0.05) in domiciliary symptoms and reliever use. There were no significant changes at 8 weeks in lung function, FeNO or blood eosinophils. Conclusions: Pragmatic switching from fine to extra-fine particle ICS at half the dose was associated with clinically relevant improvements in asthma control and quality of life, but not lung function or type 2 biomarkers.