Effects of Omalizumab Compared to Non-Omalizumab Treatment in Asthma Patients

1\. Primary and secondary outcomes and analysis methods (1) Primary endpoint Comparison of asthma exacerbation rates of omalizumab-treated vs non-Omalizumab treated group at outcome period (6 months). (asthma exacerbation: at least 1 systemic steroid treatment and/or bursts of systemic oral steroid use by prednisone-equivalent dose ≥45mg/3days, in a 6 month for relieving asthma exacerbations.) Fisher's exact test is examined for asthma exacerbation between omalizumab-treated vs non-Omalizumab treated group. (2) Secondary endpoint * Comparison of the clinical parameters Asthma exacerbation rate, ICS sparing effect, OCS requirement, lung function (FEV1%), Healthcare resource use (asthma-related ER visit/hospitalization) 1. Within Omalizumab-treated group between baseline and outcome period 2. Between Omalizumab-treated and not-treated groups at outcome period For comparison of within group, paired T-test and McNemar test are applied for continuous and categorical parameters, respectively. And, T-test and Fisher's exact test are examined for continuous and categorical parameters between Omalizumab-treated and not-treated groups. Incidentally, non-parametric tests will be examined as needed. * Finding predictor of favorable responders to Omalizumab at 6 months. (Favorable responder: 50% reduction of asthma exacerbation or of steroid requirement during 6 months with/without ICS/LABA) Candidate factors: Omalizumab treatment period/monthly dose, age, gender, asthma treatment duration, total IgE, sputum cell profile, peripheral eosinophilia serum periostin level, anti-asthmatic drug requirements etc. Binary logistic regression is used for finding predictor of favorable responders. If a serious imbalance of dependent parameter occurs from a low frequency of favorable responder, the descriptive analysis will be applied with T-test and Fisher's exact test.