Introduction

Advice

Asthma affects 3.4 million people in England (Health and Social Care Information Centre Quality and Outcomes Framework 2015). As observed in NICE technology appraisal guidance on omalizumab for treating severe persistent allergic asthma, prevalence is highest in children aged 5 to 15 years, and decreases in adulthood until age 55 to 64 years when it rises again. In adults, asthma is more common in women than men (Simpson 2010). Asthma exacerbations lead to costs of £800 million on pharmaceuticals, a direct cost to the NHS of £1 billion and indirect societal costs (time off work and lost productivity) of £6 billion per year (NHS England standard contract 2013). The British Thoracic Society (BTS) and Scottish Intercollegiate Guidelines Network have produced a joint guideline recommending a stepwise approach in the management of asthma (BTS/SIGN 2014).

Severe, difficult to control asthma affects up to 5% of people with asthma (around 140 people per million population; NHS England standard contract 2013). Patients with severe, difficult to control asthma have ongoing daily symptoms, despite therapy at step 4/5 of the BTS/SIGN guideline, that reduce quality of life and cause fatigue and absence from work (BTS/SIGN 2014). Psychological problems, including stress, anxiety and depression, are up to 6 times more common in people with this condition than in the general population. People with severe, difficult to control asthma are more likely to be admitted to hospital and to need unscheduled care than those with mild or moderate asthma (NHS England standard contract 2013).

Increased airway smooth muscle is a characteristic of asthma, particularly when severe and difficult to control. The contraction of airway smooth muscle during an asthma attack decreases the internal diameter of the airways, making it difficult to breathe (Cox et al. 2007).

There is no cure for asthma. Treatment aims to control symptoms with minimal side effects.