Figure 1.

Longitudinal change in bronchial responsiveness in 3 patients with cough variant asthma who developed typical asthma while did not taking inhaled corticosteroids. PC20-FEV1, provocative concentration of methacholine causing a 20% or greater fall in forced expiratory volume in 1 second (FEV1), was determined by a mouth tidal breathing method. Bronchial responsiveness was not obviously increased following onset of typical asthma. ICS, inhaled corticosteroids. Arrows indicate onset of typical asthma.