Most adults with asthma achieve good or very good control of their disease and are able to lead a normal life, punctuated only by the need to take small amounts of regular medication and by occasional exacerbations. A small subgroup of about 10% of adults with asthma have persisting symptoms and exacerbations despite taking adequate treatment at the highest doses; the impact of this severe or ‘difficult-to-control’ asthma is often significant and many of these patients struggle at home and at work, and are prone to the adverse side- effects of treatment, particularly those associated with oral corticosteroids at high doses. Asthmatics of particular concern are those who smoke or are exposed to passive smoking, which can make asthma worse. The challenge of severe asthma is to find ways of controlling the frequency of exacerbations and reversing the chronic airflow obstruction that are the most frequent hallmarks of this condition, despite the use of optimal anti-asthma treatment.
The most important long-term consequence of asthma is the development of persistent airway narrowing, which is non- or poorly responsive to treatment; it is unclear whether this is preventable by regular treatment with controller therapies. Death from asthma, although very uncommon in Europe, can occur in adults with all forms of the disease, especially if treatment has been suboptimal.