The primary objective is to assess the clinical effectiveness of long-term omalizumab therapy in 240 patients treated over an 8 year period in a real-life clinical setting and to compare the pre- and post-treatment clinical characteristics to identify and better understand the markers of response to omalizumab.

To date, there are no established criteria for identifying 'response' to omalizumab therapy. Currently, the commonly accepted clinical criterion for omalizumab treatment response is the physician's overall assessment, GETE (Global Evaluation of Treatment Effectiveness). Most clinical trials have evaluated the efficacy of omalizumab treatment after a 16 week treatment period and lack the impact of long-term omalizumab therapy.

Investigators propose multiple approach modules to better assess and identify 'response' and to define 'responders' to omalizumab and evaluate the long-term impact in a real-world clinical practice. Besides evaluating individual outcome variables, it is important to attempt the 'clustering of variables' to further investigate if any baseline clinical phenotypes are predictive of better response enabling us to refine the patient population who will gain most benefit from therapy.

Medical records from 240 omalizumab-treated patients will be evaluated. Comprehensive data will be collected for any asthma-related event (see evaluation criteria below), omalizumab dose, asthma-medications, spirometry, asthma control test (ACT) and any respiratory infection and/or antibiotic use since last visit. Data will be analyzed to compare the clinical phenotypes and outcome among patients to identify, characterize and define 'responders' and 'non-responders' to omalizumab. Periodic assessments for demonstrated level of response and need for continued therapy will be evaluated quarterly. Also, real-life patient adherence data to long-term omalizumab therapy will be analyzed and the factors for withdrawal and non-adherence will be identified.

Reduction in annualized rate of asthma exacerbation, steroid bursts and oral steroid dosage, ER/unscheduled doctor's visits, hospitalization and improvement in spirometry and ACT score and review of asthma medications will be evaluated quarterly. 'Cluster analysis' will be performed by grouping variables (such as age, asthma duration and severity, dosage, therapy duration, sensitization profile, IgE levels etc.) in effort to identify groups of responders.

Inclusion Criteria:

1. Moderate-to-severe persistent allergic asthmatic patients with inadequate asthma control
2. Received Omalizumab therapy per steps 5 & 6 of the NHLBI guidelines
3. Positive skin test or in-vitro specific IgE to perennial allergens
4. Measured baseline total serum IgE level (within 1 year from first dose)
5. Patient followed at AAIAST/AARC (from February 2004 to December 2011)

Exclusion Criteria:

• N/A; retrospective study

Single-center, retrospective study; total 240 patients. All 240 patients with moderate-to-severe allergic asthma who have received Omalizumab therapy at AAIAST/AARC [from February 2004 to December 2011].