Asthma is a chronic inflammatory disease of the airways that causes recurring episodes of wheezing, breathlessness, chest tightness and coughing, particularly at night or in the early morning. Three terms are used to describe the course of asthma: asthma control, asthma severity and asthma exacerbations. Asthma control is assessed by symptoms, activities of daily living and quality of life. It also includes the likelihood of loss of control, exacerbations, decline in respiratory function, and the side-effects of treatment. Asthma severity describes the difficulty in controlling asthma with treatment, reflecting the level of treatment required and the activity of disease during treatment. Asthma exacerbations are episodes of worsening of symptoms that necessitate additional treatment: asthma is severe if systemic corticosteroid treatment is needed and it requires treatment in hospital or in an emergency room.
Asthma is a common disease that affects people of all ages in all countries of Europe. Most commonly it arises in childhood and may persist into adulthood (see chapter 11). In perhaps two-thirds of children with asthma, the disease remits in the early teenage years, only to relapse, in about a third of these cases, in adulthood. Less commonly, the disease begins for the first time in adulthood. Thus, adult asthma may represent persistent or relapsed childhood disease or true incident ‘new’ adult disease. Adult asthma is frequently associated with allergies and/or accompanied by other allergic conditions such as hayfever.