Nocturnal TLA for Severe Allergic Asthma After Withdrawal of Omalizumab Therapy

This is a randomized, controlled study with a 48-week treatment phase to determine the clinical efficacy of temperature controlled laminar flow device (TLA, Airsonett™) in the patients with severe allergic asthma who are withdrawal of omalizumab therapy. All patients will be recruited from outpatient clinics of Thoracic Department of Chang Gung Memorial Hospital and meet the inclusion criteria. After entry the study, these patients will continuous their concomitant asthma medicines, except the treatment of omalizumab. These patients will be randomized (1:1) to receive TLA device or matching Control group. The participants will be recorded by randomized number to protect their private information. To minimize a potential treatment group imbalance of clinical asthma management practice and concomitant asthma medication use, randomization will be stratified by concomitant asthma medication \[in addition to inhaled corticosteroid (ICS) and long-acting β2-agonist (LABA)\] use at baseline: (1) patients not receiving theophylline, oral β2-agonists, antileukotrienes or maintenance oral steroids; (2) patients receiving one or more from theophylline, oral β2-agonists and anti-leukotrienes, but not receiving maintenance oral steroids; (3) patients receiving maintenance oral steroids. The doses of ICS and LABA (taken separately or as a fixed combination) and other concomitant asthma medications will be kept constant through the treatment period. If they have asthma exacerbation of emergency visit or/and hospitalization, or \> or =2 episodes of asthma exacerbation (defined as a worsening of asthma symptoms requiring treatment with systemic corticosteroids), the patients either with TLA or Control group will return to start the omalizumab therapy till the end of 48-week follow-up. Omalizumab dose is based on the patient's body weight and total serum immunoglobulin E (IgE) level at screening and is administered every 2 or 4 weeks to provide a dose of at least 0.016 mg/kg per IU/ml of IgE. Patients are permitted short-acting β2-agonist rescue medication as required. Patients make study visits at weeks 0, 2, 4, 12, 24, 36 and 48 of the treatment phase. The primary efficacy variable is the first time to asthma exacerbations during the 48-week TLA treatment phase. Rate of hospitalization, and emergency visit per year will be also recorded. Diary cards are used to record the clinical symptom score, asthma control test (ACT) and use of rescue medication in the internet of Asthma Help. Quality of life will be assessed using the Sino-Nasal Outcome Test (SNOT-22) score at weeks 0, 12, 24, 36 and 48 of the treatment phase. Spirometry and exhaled NO will be performed at each visit. All visits include assessment of vital signs and physical examination.