Our results suggest that airway vascular leakage is a major pathophysiologic feature of early asthma deterioration, occurring before recrudescence of cellular inflammation.

These data suggest that clinical markers remain the most sensitive measures of early deterioration in asthma during back-titration of ICS, occurring at a time when AHR and conventional indices of asthmatic airway inflammation appear unchanged. These findings have major relevance to management and to how back-titration of ICS therapy is monitored.