Abstract
BACKGROUND: Omalizumab (OMA) is an effective anti-immunoglobulin E (IgE) treatment for moderate-to-severe asthma. However, predicting an individual's response is difficult. Monitoring change of total serum IgE may be useful for predicting the response to OMA. The purpose of this study was to determine if measuring the change in total IgE level could predict the response to OMA in patients with moderate-to-severe asthma. METHODS: This study included 25 patients (11 females and 14 males; mean age =46.1 years; mean pre-bronchodilator FEV1% =67.8%) with moderate-to-severe asthma. All patients were treated with OMA, and total IgE serum concentrations were measured at baseline before treatment (median baseline total serum IgE =210 IU/mL) and at 4 weeks after beginning treatment. Patients were divided into responders (i.e., excellent or good response) and non-responders (i.e., moderate or poor response) using the global treatment effectiveness (GETE) response method after 16 weeks of treatment. The characteristics of responders and non-responders were compared, and receiver operating characteristic (ROC) curve analysis was used to determine the ability of change in IgE level to predict treatment response. RESULTS: There were 20 responders (80%) and 5 non-responders (20%), and responders demonstrated better improvements of asthma control test (ACT) and asthma control questionnaire (ACQ) scores, and reduction of oral corticosteroid use as compared with non-responders. Twenty-one patients had a total serum IgE 4-week-to-baseline ratio ≥2, and 20 of the patients responded to OMA. The area under the ROC curve (AUC) for baseline IgE level for predicting treatment response was 0.53 (95% CI: 0.18-0.88), and that of the week 4 IgE level was 0.69 (95% CI: 0.42-0.96). Using a cutoff value of 2, the 4-week: baseline IgE ratio achieved the highest AUC of 0.87 (95% CI: 0.64-1), with a sensitivity and specificity of 100% and 80%, respectively, for predicting treatment response. CONCLUSIONS: A total week 4 serum IgE level:baseline level ratio ≥2 can predict the response to OMA in patients with moderate-to-severe asthma after 16 weeks of treatment with high likelihood. Monitoring changes of total IgE level in asthma patients treated OMA may be useful for predicting clinical response.