4-month omalizumab efficacy outcomes for severe allergic asthma: the Dutch National Omalizumab in Asthma Registry

Background: Omalizumab is licensed as add-on therapy for patients with severe allergic asthma. Response is in most studies scored by the physician's global evaluation of treatment effectiveness (GETE). A good clinical and validated parameter for treatment response is currently missing. Also, there are no established criteria for identifying patients who will respond to omalizumab based on pre-treatment characteristics. The Dutch National Omalizumab in Asthma Registry was developed in 2011 to better evaluate inclusion criteria and measure treatment response after 4 months. Methods: This is a "real world" prospectively designed, observational data registry in which the outcomes of patients who received omalizumab between 2012 and 2015 were evaluated. Data were collected from all centers in the Netherlands comprising demographic features, criteria for starting treatment, GETE, FEV1, oral corticosteroid use and ACQ. Results: 65.5% of the 403 patients had a good or excellent response to omalizumab after 16 weeks according to the treating physician GETE. 64.5% fulfilled all the criteria for prescribing omalizumab at baseline. The mean ACQ improved from 2.96 at baseline to 1.83 at 16 weeks (p <0.001). 75.3% of the responders showed more than 0.5 points improvement in the ACQ. The mean FEV1 increased from 71.58 to 79.06 (p <0.001). There was no relationship between patients with a FEV1 <80 and >= 80% at baseline and response (p = 0.981). Most of the responders had a considerable improvement of FEV1 either/or ACQ or OCS use (88.3%). While 86.7% of the responders had an improvement of either ACQ or FEV1. 75.4% of the responders had an improvement of ACQ, while 50.4% had an improvement of FEV1. Finally 11.7% of the patients with no improvement of FEV1, ACQ or OCS use were considered to have a good response. Conclusions: This registry of 403 inadequately controlled severe allergic asthma patients in the Netherlands showed a good or excellent response of 65.5% to omalizumab after 16 weeks, in accordance with previous studies. The assumption that careful registration would lead to higher response rates could not be supported by the data from this registry. Improvement of ACQ appears to be a useful additional assessment tool to measure response in omalizumab treated patients