Omalizumab for treating severe persistent allergic asthma

Asthma is a long‑term inflammatory disorder of the airways characterised by signs or symptoms including breathlessness, chest tightness, wheezing, sputum production, airflow obstruction, hyper‑responsiveness of airways and cough (particularly at night). Symptoms vary in frequency and severity, from intermittent and mild, to frequent and severe. Allergic and non‑allergic forms of asthma exist. Allergic asthma results from excess immunoglobulin E (IgE) produced in response to environmental allergens such as house dust mites, pollen and moulds. Non‑allergic asthma can be triggered by factors such as anxiety, stress, exercise, cold air, smoke and infection.

The Quality and Outcomes Framework (2008) estimated that 5.9% of the UK population receives treatment for asthma. Prevalence is highest in children aged 5 to 15 years, and decreases in adulthood until the age range of 55 to 64 years, when it rises again. In 2008 to 2009, there were over 67,000 emergency hospital visits for asthma in the UK, with more than 40% of these for children aged 15 years or under. People with asthma may have an impaired quality of life, with symptoms leading to fatigue, and absence from school or work. Psychological problems, which can include stress, anxiety and depression, are up to 6 times more common than in the general population, and are particularly common in people with severe and difficult‑to‑control asthma. There are between 1000 and 1200 deaths from asthma each year in the UK, where, in 2008, the rate of premature death from asthma was 1.5 times higher than in the rest of Europe.

There is no cure for asthma and the aim of treatment is to control symptoms while minimising the adverse reactions to treatment. Current guidelines from the British Thoracic Society (BTS) and Scottish Intercollegiate Guidelines Network (SIGN) recommend a stepwise approach to treatment aligned with the pathway of the Global Initiative for Asthma (GINA). Good control, characterised by no symptoms, normal lung function and no exacerbations, is achieved by stepping up or down treatment as necessary. Severe persistent allergic asthma is defined as poor control despite eliminating environmental allergens and correctly optimising standard care.

Step 1 (for mild intermittent asthma) of the GINA pathway recommends using inhaled short‑acting beta₂ agonists occasionally, and step 2 recommends introducing inhaled corticosteroids at 200 to 800 micrograms per day in people aged 12 years and over and at 200 to 400 micrograms per day in children aged 5 to 12 years. Step 3 recommends adding an inhaled long‑acting beta₂ agonist and, if control remains inadequate, increasing the dosage of inhaled corticosteroids to 800 micrograms per day in adults and adolescents and to 400 micrograms per day in children. If a person's asthma does not respond to an inhaled long‑acting beta₂ agonist, a leukotriene receptor antagonist (oral), a theophylline (oral) or a slow‑release beta₂ agonist (oral) may be considered instead. Step 4 recommends increasing the dosage of inhaled corticosteroids to up to 2000 micrograms per day in adults and adolescents and up to 800 micrograms per day in children. As with step 3, adding a leukotriene receptor antagonist, a theophylline or an oral beta₂ agonist may also be considered. Before moving to step 5, clinicians should refer people whose asthma is inadequately controlled to specialist care. Step 5 recommends daily corticosteroid tablets at the lowest dose that provides adequate control, alongside high‑dose inhaled corticosteroids. Treatments that can minimise the use of corticosteroid tablets may also be considered. The adverse effects of long‑term oral corticosteroids are significant and include adrenal suppression, glucose intolerance, decreased bone mineral density, cataracts and glaucoma, and growth failure in children.