In the UK, approximately 1 in 12 of the population (4.3 million adults and 1.1 million children) currently receive treatment for asthma, at an annual cost to the NHS of about £1 billion. Asthma prevalence has remained steady since the late 1990s, with an estimated 320,000 new diagnoses each year, and 1167 asthma‑related deaths recorded in 2011. Asthma UK estimates that 75% of hospital admissions for asthma are avoidable, and that 90% of deaths from asthma are preventable. About 5% of people with asthma are unable to control their asthma with high levels of medication. People in this group may have difficulty breathing almost all of the time, as well as frequent serious and life‑threatening exacerbations that need hospital treatment. The management of asthma is well described in established national guidelines, based on a step‑wise approach to treatment.