Abstract
Intro: Omalizumab (Xolair) is licensed for the treatment of severe allergic asthma patients with IgE mediated disease. Dose calculation is governed by total IgE and weight. Stringent controls in prescribing mean patients deemed clinically appropriate to commence treatment are illegible as consequence of IgE levels outside of the dosing table. Our aim was to identify the fluctuation of IgE, to ascertain if a degree of flexibility should be considered when prescribing Omalizumab.
Methods: Retrospectively the total serum IgEs of patients whom were referred to potentially start therapy were reviewed. Patients with 2 or more IgEs within a six month period were included. The range of variability of IgE and percentage of variability between the two IgEs were recorded.
Results: n=29. IgE 1 median=460 (IQR 155.5-870.0), IgE 2 median=340 (IQR 140.0-885). All IgE's varied with 14 increasing and 15 decreasing. The average IgE variation was 89 IU/ML (IQR 75-123, median 98). This equated to an average percentage variation of 36.6% (IQR 13.5%-40.7%, median 23.1%).
There was no statistically significant difference between IgE 1 and 2 yet, the variation in IgE 2 resulted in an additional 4 of the 29 patients becoming eligible for treatment and the dose could have been altered in 8 of the 19 patients whose IgE 1 was in the dosing range. This would mean that overall 79% of patients were eligible for Omalizumab instead of 66%.
Conclusion: Our data collected shows that Serum IgE has significant variability, and therefore frequent testing of IgE in patients whom are potential for Omalizumab therapy and do not meet dosing criteria on initial review should have repeat measures of serum IgE.
- Copyright ©the authors 2016