Time to Reinvent the Wheel
This particular article contains a lot of advanced knowledge
about asthma. Respiratory therapists continue to study and learn about
the science and techniques for managing asthma so that they can help
you breath better. If you are a long-time asthma sufferer and have studied
about your disease, you may find this discussion of categorizing asthma
control as important information in your arsenal of knowledge. Again,
this article appeared earlier this year in AARC Times.
Advances in the management of asthma
Asthma is the most common chronic condition of childhood and affects more than 6.3 million children in the United States alone. The National Health Interview Survey (2002) reports a prevalence rate of 12% of children aged 0–17 have been told by a physician that they have asthma. The focus of asthma disease management has drifted from one of disease severity to one of asthma disease control.
Severity versus control
The problem with classifying disease severity is that by its very nature, the classification implies a fixed component of asthma. Asthma is a disease that can change over weeks, months, or years with treatment or without treatment. Asthma severity not only encompassed the underlying severity of the asthma, but its responsiveness (or lack thereof) to an appropriate treatment regimen.
The key, of course, to stratifying disease severity based on patient symptoms was that once the disease severity was identified, a medication regimen could be established based on the severity level. The medication regimen then could be increased, decreased, or left alone on subsequent follow-up visits based on the patient’s self-report of asthma symptoms and spirometry (if patients were above the age of seven).
The difficulty with the focusing of asthma disease management on disease severity, of course, comes with long-term follow-up of these patients. For example, the patient who is identified as having moderate persistent asthma is prescribed inhaled corticosteroids (and possible adjuncts) for daily maintenance and beta agonists for symptom relief. Twelve months later, the patient reports no symptoms (mild intermittent), and the question becomes how to adjust or should you adjust the medication regimen by stepping the patient down in therapy. The answer may lie not in the severity of the disease but in the control of asthma. The newly released GINA guidelines stress the importance of disease control in asthma management (see Table 1 and Figure 1).4 It is also expected that the third edition of the NAEPP guidelines to be released in 2007 will focus heavily on asthma control as well.
Another major difference between control and severity is the duration of the assessment period: Severity is assessed over the preceding six months to one year, whereas control refers to the preceding weeks (one week to three months). Thus, while the level of control has to be evaluated at each visit and may change from one visit to another, reclassification of severity should be envisaged only when a stable level of control has been obtained and maintained during several (e.g., at least three) months, allowing to decrease the “therapeutic pressure.”5
The question becomes how to measure asthma control. The Joint Task Force on Practice Parameters for Allergy & Immunology suggested a multifactorial approach for clinicians to judge asthma control on daytime and nocturnal symptoms, use of rescue medication, limitations of daily activity, patient and physician assessment, and spirometry.9
While there is no comprehensive measurement tool to identify and define asthma control, several instruments have been developed, tested, and validated over the last several years for their reliability and reproducibility to measure asthma control. The Asthma Control Test,10 the Asthma Quality of Life Questionnaire,11 the Asthma Therapy Assessment Questionnaire,12 and the Asthma Control Scoring System13 are four of those survey instruments currently available.
These validated tools all take a slightly different approach to determining or assessing asthma control. For example, the Asthma Control Tests are either five- or seven-item question assessments of asthma control completed by the asthmatic (12 years of age or greater) or the child and parent/caregiver (four to 11 years of age), respectively.10 It is designed to identify patients whose asthma is inadequately controlled and is available on the Web in both English and Spanish (www.asthmacontrol.com). The most recent instrument in the literature, the Asthma Control Scoring System,13 assesses three types of parameters:
To date, there has been no definitive study contrasting or comparing these two disease management principles of severity versus control, and it is possible that a mixture of control and severity may improve asthma management. The ability to measure and quantify asthma control appears easier to operationalize in real world, clinical practice. The variability of asthma over prolonged periods of time makes disease management and treatment regimens based on disease severity difficult. Monitoring asthma control with validated instruments may better assess disease outcomes and medication regimens for both short- and long-term management. •
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