A Framework for Assessing Impairment from Asthma: Determination of Disease Severity (1)In preparation for the writing of this paper, I reviewed 27,515 articles on asthma, published since 1968, through the use of the computerized bibliographic retrieval system, P&per Chase. Only 75, or less than 0.05%, mentioned severity, and only 14, or 0.005%, mentioned impairment. Disability was mentioned in 63, or less than 0.05%. Over half of these were in non-English medical journals. Clearly, if we wish to develop rational guidelines for asthma impairment, we must devote greater research efforts to understanding disease severity and impairment.
The factors influencing asthma severity have been separated into two groups: epidemiologic and clinical (Table 3). Each group will be discussed in turn. Unfortunately, adequate information is lacking on most of these factors. An especially noticeable lack is any relationship to disease prognosis. In addition, lack of consensus exists as to the best measures of disease severity. buy asthma inhaler
Level of Lung Function
Level of lung function is strongly associated with bronchial responsiveness: the lower the initial level of lung function, the greater the responsiveness. This association may in part be due to anatomic or geometric factors, including aerosol particle deposition, the relationship of airway resistance to the fourth power of the airway radius, the increase in peripheral airways resistance relative to central airways resistance as the level of lung function falls, and loss of tractional support of the airways.

Table 3—Measures of Asthma Severity

Epidemiologic Clinical
Level of lung function Duration of disease
Degree of bronchial responsiveness Emergency room visits
Gender Hospitalizations
Race Physician visits
Atopy Circadian variability
Smoking Medication use
Wheeze symptoms