Less Airway Reactivity in Nonwheezing Asthmatics Compared to Wheezing Asthmatics

Abstract

It has recently been shown that cough and/or dyspnea may be the only presenting manifestations of asthma. To determine whether the degree of airway reactivity differentiates asthmatics who wheeze from those asthmatics who do not, we prospec-tively evaluated the responses to an inhalational challenge by methacholine (acetyl beta methylcholine) in 44 patients referred to our laboratory with a diagnosis of asthma and with a normal baseline FEV1/FVC%. In decreasing FEV1 20% from baseline, wheezers needed only 53 cumulative dose units of methacholine, while nonwheezers needed 102 (P < 0.01). In response to five dose units of methacholine, wheezers decreased their FEV₁ from baseline by an average of 15%, while nonwheez-ers decreased theirs by 5% (P < 0.05). We conclude that airways of asthmatics with a history of wheeze are more reactive to a cholinergic challenge than airways of asthmatics without a history of wheeze. Although airway reactivity may help explain why some asthmatics wheeze and others do not, it is not the sole explanation. There was considerable overlap in airway reactivity between both groups.