Background: In the primary care setting, patients often report that their asthma began after an acute respiratory infection such as bronchitis, pneumonia, or an influenza-like illness ("infectious asthma"). Preceding respiratory illnesses such as bronchitis and pneumonia are also epidemiologic correlates of asthma in both children and adults. These associations suggest the possibility that respiratory infection is involved in the initiation of asthma in addition to the already acknowledged role of infection in asthma exacerbations. The purpose of this study was to investigate whether a history of infectious asthma influenced clinical and pulmonary function characteristics of patients with chronic asthma.
Methods: Conducted in a community-based primary care practice, this is a clinical descriptive study of 92 middle-class patients who had a mean age of 37.7 years (standard deviation 15.4 years), a clinical diagnosis of chronic asthma, and baseline pulmonary function test results available for analysis.
Results: There was sufficient history available to classify asthma as infectious in 41 (45%) of 92 patients. Patients with infectious asthma reported a much shorter duration of asthma symptoms than did patients with atopic, occupational, and exercise-induced asthma (5.6 vs 13.3 years, P = .001). Nevertheless, patients with infectious asthma had significantly worse percentages of predicted FEV1 and FEF25%-75%, both before and after bronchodilator therapy.
Conclusions: Infectious asthma was common in this primary care setting. Compared with patients with other asthma syndromes, those with infectious asthma had worse pulmonary function despite a shorter duration of symptomatic disease. Further studies of the cause and prognosis of this clinical entity are warranted.