2 Clinical Need and Practice
2.1 Asthma is a common disease that produces symptoms of wheezing and breathlessness. It affects the lower airways and results in narrowing (bronchoconstriction) of the airways with consequent reduction in the flow of gases between the airways and lung alveoli. It can be triggered by a variety of environmental factors such as infection, allergy, airborne chemicals and also exercise. There are a number of patterns of lower airways disease in early childhood that results in two predominant clinical patterns (acute wheezy episodes and recurrent day to day symptoms) that may occur separately or together in the child.
2.2 The overall prevalence of asthma in England and Wales is around 8% to 10% although not all cases are currently being treated. In all children under the age of 5 years about 9% of boys and 6% of girls are prescribed inhalers. There is a strong genetic component in the aetiology of this disease. There is also wide geographical variation in prevalence, with asthma being more common in, for example, urban rather than rural communities. It has a wide range of severity, is the cause of considerable morbidity and a rare cause of death.
2.3 The primary objective of asthma treatment is to achieve optimal control of the disease by reducing exacerbations, increasing lung function and limiting symptoms in order to maximise the quality of life of the child. This is currently best achieved by delivering both symptom relieving (bronchodilators – including ß2 agonists and anticholinergics) and preventive anti-inflammatory drugs (typically corticosteroids) by inhalation. In the UK, asthma treatment is strongly influenced by the 1997 guidelines of the British Thoracic Society (BTS), which promote step-wise management of increasingly severe asthma. The 1997 BTS guidelines are mainly based on a consensus of expert opinion.
2.4 The estimated annual drug cost for asthma to the NHS in England and Wales in all age groups is approximately £115 million. In children under the age of 5 years this cost is about £8 million.