This information is taken from the revised GINA Report, Global Strategy for Asthma Management and Prevention (2007), available on the Global Initiative for Asthma (GINA) website. Please refer to the full guideline document for more detailed information.
Aetiology
Many attempts have been made to classify asthma according to aetiology, particularly with regard to nvironmental sensitizing agents. However, such a classification is limited by the existence of patients in whom no environmental cause can be identified. Despite this, an effort to identify an environmental cause for asthma (for example, occupational asthma) should be part of the initial assessment to enable the use of avoidance strategies in asthma management. Describing patients as having allergic asthma is usually of little benefit, since single specific causative agents are seldom identified.
Asthma Severity
Previous GINA documents subdivided asthma by severity based on the level of symptoms, airflow limitation, and lung function variability into four categories: Intermittent, Mild Persistent, Moderate Persistent, or Severe Persistent (Figure 2-4). Classification of asthma by severity is useful when decisions are being made about management at the initial assessment of a patient. It is important to recognize, however, that asthma severity involves both the severity of the underlying disease and its responsiveness to treatment1. Thus, asthma can present with severe symptoms and airflow obstruction and be classified as Severe Persistent on initial presentation, but respond fully to treatment and then be classified as Moderate Persistent asthma. In addition, severity is not an unvarying feature of an individual patient’s asthma, but may change over months or years.
| Intermittent |
| Symptoms less than once a week Brief exacerbations Nocturnal symptoms not more than twice a month
|
| Mild Persistent |
| Symptoms more than once a week but less than once a day Exacerbations may affect activity and sleep Nocturnal symptoms more than twice a month
|
| Moderate Persistent |
| Symptoms daily Exacerbations may affect activity and sleep Nocturnal symptoms more than once a week Daily use of inhaled short-acting β2-agonist
|
| Severe Persistent |
| Symptoms daily Frequent exacerbations Frequent nocturnal asthma symptoms Limitation of physical activities
|
* The worst feature determines the severity classification.
Because of these considerations, the classification of asthma severity provided in Figure 2-4 which is based on expert opinion rather than evidence is no longer recommended as the basis for ongoing treatment decisions, but it may retain its value as a cross-sectional means of characterizing a group of patients with asthma who are not on inhaled glucocorticosteroid treatment, as in selecting patients for inclusion in an asthma study. Its main limitation is its poor value in predicting what treatment will be required and what a patient’s response to that treatment might be. For this purpose, a periodic assessment of asthma control is more relevant and useful.
References:
1. Tarlo SM, Liss GM. Occupational asthma: an approach to diagnosis and management. CMAJ 2003;168(7):867-71.