However, there are a number of approaches to classifying asthma. Asthma classifications may be made according to one of more of the following methods:
- Classifications of asthma by underlying cause or disease process
- Classification of asthma by severity
- Asthma classification by degree of control
We'll examine each method separately.
Classifications of Asthma by Underlying Cause or Disease Process
One way to classify asthma is by separating asthma into different types or causes, though that is not truly an asthma classifications scheme. The most common cause of asthma is allergies, but there are several other types of asthma as well. Here is a list of types of asthma.
- Allergic asthma. In this type of asthma, symptoms are triggered by environmental triggers called allergens, such as pollen, dust mites, and pet dander.
- Non-allergic asthma. This type of asthma is triggered by factors other than allergens, such as irritants like smoke.
- Occupational asthma. This type of asthma is triggered by irritants in the workplace, such as strong fumes or chemicals.
- Exercise-induced asthma. When asthma symptoms are triggered by exercise or vigorous exertion, it is called exercise-induced asthma.
- Cough-variant asthma. With this kind of asthma, the main symptom is continuous coughing. There may be shortness of breath, but generally there is no wheezing.
- Medication-induced asthma. Sometimes, medications such as aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs for short) can trigger asthma symptoms.
Classifying Asthma by Severity
The National Asthma Education Program, which produces the US-based asthma treatment guidelines, classifies asthma by its severity, a more commonly used scheme by most health professionals. It's a useful way to look at asthma, because it guides asthma treatment.
Classification of asthma by severity is based on frequency and severity of asthma symptoms, along with peak flow readings. Levels are referred to as steps, as follows:
- Step 1: Mild Intermittent. At this level, asthma symptoms occur less than 2 times a week during waking hours and less than twice a month during the night. In between asthma attacks, no symptoms occur at all, and the attacks themselves are generally brief, though their intensity can vary. Peak flow variability is less than 20 percent.
- Step 2: Mild Persistent. At this level, asthma symptoms are occurring more than twice a week, but not as often as daily. They may occasionally wake you up at night, but that happens less than 2 times a month. Asthma attacks may interfere with activity temporarily. Peak flow tends to be more than 20—but less than 30—percent.
- Step 3: Moderate Persistent. At this level, asthma is starting to interfere more with daily living. Symptoms are cropping up every single day, and you need to use a quick-relief inhaler daily (if you have one). Asthma attacks are occurring at least twice a week and often interfere with activity. They may last for days at a time. You are probably also waking up 1 or more times a week with symptoms. Peak flow rate varies by more than 30 percent.
- Step 4: Severe Persistent. This is the most severe form of asthma and at this level, symptoms are basically continuous. Activity is severely limited and asthma attacks and night symptoms are frequent. Peak flow varies by more than 30 percent.[
The National Asthma Education Program (NAEPP) advocates a step-wise approach to treating asthma in adults and children older than age 5, based on the levels of severity described above. For instance, mild intermittent asthma is usually treated only with quick-relief medicines, while severe persistent asthma is treated with one or more daily controller medicines and frequent use of quick-relief medicines.
A New Emphasis on Asthma Classifications by Degree of Control
The Global Initiative for Asthma (known as GINA) released new guidelines for asthma management in late 2006 that emphasized looking at asthma not only in terms of severity, but also in terms of response to treatment, which is equivalent to control.
In addition, the new GINA guidelines use this approach with children under the age of 5, which is a major difference from the NAEPP guidelines. GINA recommends using the NAEPP classifications of asthma only for research purposes. Instead, they suggest these 3 asthma classifications, which are more a variation in mindset than anything else:
- Controlled. At this level, there are no daytime or nighttime symptoms, no activity restrictions, and infrequent need for quick-relief medicines (no more than twice a week). Peak flow is normal and there are no asthma attacks.
- Partly controlled. At this level, daytime symptoms are occurring more than twice a week, sometimes at night and occasionally they limit activity. Quick-relief medicine is needed more than twice a week. Peak flow rate is less than 80 percent of your personal best, and asthma attacks occur at least once a year.
- Uncontrolled. Your asthma is classified as uncontrolled if you have 3 or more of the features of partially controlled asthma at least 3 times a week, and asthma attacks are occurring weekly.
GINA maintains that complete control of asthma is possible with the right treatment.
Sources:
Grammer, L.C. and Greenberger, P.A. (1992). Diagnosis and classification of asthma. Chest, 101, Retrieved April 22, 2007, from http://www.chestjournal.org/cgi/reprint/101/6/393S.pdf
GINA, (2006). Global strategy for asthma management and prevention. Retrieved April 22, 2007, from Global Initiative for Asthma Web site: http://www.ginasthma.org/download.asp?intId=214
National Institutes of Health, National Heart, Lung, and Blood Institute. Guidelines for the diagnosis and management of asthma. NIH Publication No. 97-4051, July 1997.
