title: Potential masking of airway eosinophilic inflammation by combination therapy in asthma.
abstract: OBJECTIVE
  Long-acting β2 agonists (LABA) may mask ongoing bronchial inflammation, leaving asthmatic patients at greater risk of severe complications. The aim of this study was to compare the effect of combination therapy using low-dose inhaled corticosteroids (ICS) plus LABA on airway inflammation in asthma to the effect of medium-dose ICS alone.
  
  
  METHODS
  Twenty-four patients with asthma not controlled by low-dose (400 µg per day) budesonide alone were enrolled in this prospective crossover study. Patients were randomized into 2 treatment phases: one receiving medium-dose (800 µg per day) budesonide (ICS phase), and the other receiving a combination therapy of low-dose budesonide/formoterol (360 µg/9 µg per day) delivered by a single inhaler (LABA phase). Each treatment phase lasted for 6 week, after which patients were crossed over. Asthma symptoms, lung function, and airway inflammation were compared between the 2 phases.
  
  
  RESULTS
  Twenty-three patients completed the study; adequate sputum samples were collected from 17 patients. Asthma symptoms and lung function remained similar between the 2 phases. However, the mean sputum eosinophil percentage was higher in the LABA phase than in the ICS phase (5.07±3.82% vs. 1.02±1.70%; P<0.01). Sputum eosinophilia (≥3%) was more frequently observed in the LABA phase than in the ICS phase (six vs. two).
  
  
  CONCLUSIONS
  Addition of LABA may mask airway eosinophilic inflammation in asthmatic patients whose symptoms are not controlled with low-dose ICS.
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Byung-Jae
authors.initials: BJ
authors.lastname: Lee
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yun-Jin
authors.initials: YJ
authors.lastname: Jeung
authors.affiliation: Center for Health Promotion, Samsung Medical Center, Seoul, Korea.
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Bundang Jaeseng Hospital, Seongnam, Korea.
authors.forename: Mi-Jung
authors.initials: MJ
authors.lastname: Oh
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Dong-Chull
authors.initials: DC
authors.lastname: Choi
keywords: Airway; asthma; beta2-agonists; corticosteroids; inflammation