The participants were randomly assigned to receive either omalizumab or a placebo, given as an injection under the skin every 2 or 4 weeks during the 48 weeks of the study. In addition, all participants received treatment with high-dose ICS and LABAs. The researchers measured how often the participants had asthma flares requiring steroids by mouth or by vein, as well as the participants' symptoms, quality of life, and use of rescue inhalers.