Severe asthma is associated with a high risk of asthma-related hospitalization and mortality (1, 2) and significantly impairs patients’ quality of life (QoL) (3). The economic burden of asthma is the greatest in patients with inadequately controlled severe persistent asthma (4). Although treatments are available for severe persistent asthma, many patients remain inadequately controlled. For example, the INSPIRE study reported that 52% of patients were classified by the Asthma Control Questionnaire as having uncontrolled asthma and 74% of patients used short-acting β2-agonists daily despite regular maintenance therapy with inhaled corticosteroids (ICS) or ICS plus a long-acting β2-agonist (LABA) (5).
Adding omalizumab, an anti-immunoglobulin (Ig) E antibody, to standard asthma therapies (ICS with or without an LABA and additional controller medications as needed) has proven efficacy in the treatment of severe persistent allergic (IgE-mediated) asthma, reducing exacerbations, emergency visits for asthma and improving QoL (6).
Analyses of clinical trial data (6) and pooled data (7–11) have found the physician’s overall assessment – a composite measure including patient interview, review of medical notes, spirometry and symptom diaries, rescue medication use and peak expiratory flow (PEF) – to be the most meaningful measure of response to omalizumab therapy (12). Graded in a five-level evaluation of asthma control (complete control; marked improvement in control; discernible but limited control; no appreciable change; worsening in control), those with marked improvement or complete control are defined as responders (12). In this responder group, clinical outcomes were further improved compared with the overall omalizumab-treated population (12). In order to target those patients who will benefit most from omalizumab, thereby minimizing unnecessary drug exposure and healthcare costs, the omalizumab European Union (EU) label states that treatment response should be assessed at 16 weeks by the physician and treatment discontinued in those judged not to respond.
Asthma exacerbations and exacerbation-related healthcare resource use are strong indicators of lack of asthma control, but can occur relatively infrequently in many patients. Day-to-day asthma symptoms are also of major relevance to patients, and therefore may be useful in demonstrating the efficacy of a given treatment.
The aims of this study were to investigate the correlation between day-to-day asthma symptoms and asthma-related QoL, and to evaluate the effect of add-on omalizumab on day-to-day control of asthma symptoms in patients with severe persistent asthma. Results in omalizumab responders were also examined.