These indices were compared in 3 groups of subjects: (1) a wheeze group, which included subjects with current persistent wheeze and/or dyspnea of grade III or higher or attacks of shortness of breath with wheeze, (2) a cough and phlegm group, consisting of subjects with chronic cough and/or chronic phelgm and/or episodes of bronchitis, and (3) a third group of asymptomatic subjects. buy prednisone
These investigators found that for subjects who responded to histamine, the distribution was log normal and there was overlap between symptomatic and asymptomatic subjects. The overlap of symptomatic and asymptomatic subjects had a greater effect than the definition of responsiveness in changing the sensitivity and specificity of the test. The relatively low prevalence of symptoms generally contributed to the poor predictive power of bronchial challenge testing.
In these data and other population-based data, however, careful analysis suggests that an operational definition of asthma could be developed based solely on challenge test data.
Different definitions of disease are appropriate, depending on the use of the definition—that is, whether the definition is used for screening, clinical diagnosis, or impairment assessment. For the purpose of impairment assessment, a highly specific definition of disease is necessary. Although clinical asthma evaluation need not require nonspecific challenge testing, such testing is mandatory in assessing the degree of physiologic impairment from asthma, occupational or otherwise.