ABC of Asthma

Asthma is an overall descriptive term but there are a number of more or less distinct phenotypes which may have different causes, clinical patterns and responses to treatment The clinical characteristic of asthma is airflow obstruction, which can be reversed over short periods of time or with treatment In the great majority of asthmatics, treatment is available to suppress asthma symptoms to allow normal activity without significant adverse effects Five to ten percent of asthmatics have asthma where control is difficult or side effects of treatment are troublesome Inflammation in the airway wall is an important feature of asthma and involves oedema, infiltration with a variety of cells, disruption and detachment of the epithelial layer and mucus gland hypertrophy Asthma is a common condition that has increased in prevalence throughout the world over the last 20 years. It is estimated that around 300 million people are affected across the world. There is no precise, universally agreed definition of asthma (Box 1.1). The descriptive statements that exist include references to the inflammation in the lungs, the increased responsiveness of the airways and the reversibility of the airflow obstruction.

The International Consensus Report on the Diagnosis and Management of Asthma (Global Strategy for Asthma Management and Prevention) gives the following definition: ’Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role.