Adults with asthma present with a spectrum of signs and symptoms that vary in severity from patient to patient, and within the same patient over time. Some patients complain of very few mild symptoms while others present with more severe symptoms despite having only mild airflow obstruction. Airway function should be measured routinely by tests such as forced expiratory volume in 1 second (FEV1) or peak expiratory flow (PEF).
The clinical manifestations of asthma include recurrent episodes of wheezing, chest tightness, cough and shortness of breath. The symptoms are often worse at night or on waking from sleep. Usually, they resolve spontaneously or with the inhalation of a reliever medication. In other cases, they may worsen over hours or minutes, leading to more severe airflow obstruction and an ‘attack’ or exacerbation of asthma that is relieved only by extra medication. Some very severe episodes are life-threatening, although death from asthma in adulthood is uncommon (figure 2) and in most European countries mortality rates are falling.
Exacerbations of asthma are mostly provoked by respiratory infections – usually viral in origin – and are especially common in winter and shortly after the return of children to school after the summer holiday. In adults with allergic asthma (as indicated by the co-presence of rhinitis and conjunctivitis), symptoms are provoked by exposure to the relevant allergen(s), commonly those in house dust or from pets, or encountered at work. Other common triggers include physical exertion (particularly in cold, dry air) and traffic pollution. Certain drugs such as β-adrenergic blockers and nonsteroidal anti-inflammatory agents can provoke asthma. A rare, but characteristic form of adult-onset asthma presents with nasal polyps and symptoms provoked by taking aspirin or similar nonsteroidal anti-inflammatory agents; its mechanism is unclear. Asthma exacerbations remain the main reason for admission of people with asthma to hospital. While rates of hospital admission have gradually fallen in recent years, they remain high, particularly in the UK, Spain and Belgium (figure 3).
One important type of disease that arises in adulthood is occupational asthma, which is induced by airborne agents encountered in the workplace. Occupations in which there is a high risk of occupational asthma include baking, spray painting, chemical processing, detergent manufacture and hairdressing. In addition, adults with asthma of unknown origin may find that irritant exposures or physical exertion at work exacerbate their disease. It is estimated that, in these ways, some 15% of all adult asthma is ‘work related’ (see chapter 24).