Airway wall thickness in asthma assessed by computed tomography - Relationto clinical indices

Postmortem studies have shown that airway wall thickening is present in ast hmatic patients and may play a pathophysiologic role. We investigated the p resence and characteristics of airway wall thickening in patients with asth ma, using helical computed tomography. Eighty-one asthmatic patients and 28 healthy control subjects were studied cross-sectionally. Airway wall thick ness was assessed by a validated method on the basis of wall area (WA), WA corrected by body surface area (WA/BSA), and WA%, defined as (WA/total area ) x 100 at the apical bronchus of the right upper lobe. Airway luminal area (Ai) and Ai/BSA were also examined. Asthma duration and severity, pulmonar y function, and serum eosinophil cationic protein levels were evaluated. In traobserver and interobserver reproducibility of WA, WA%, and Ai measuremen ts were good. As compared with control, WA, WA/BSA, and WA% were significan tly increased in patients with mild (n = 13), moderate (39), and severe per sistent (22) asthma but not in patients with intermittent asthma (7). Compa rison of the four asthmatic subgroups demonstrated thicker airways in more severe disease, but no difference in Ai or Ai/BSA. When all asthmatic patie nts were analyzed together, WA and WA/BSA correlated with the duration, alt hough weakly, and severity of asthma. WA and WA/BSA negatively correlated w ith FEV1 (percentage of predicted), FEV1/FVC (%), and FEF25-75% (percentage of predicted), whereas WA% negatively correlated with only FEV1. We conclu de that airway wall thickening occurs in patients with asthma and is not li mited to those with severe disease. The degree of airway wall thickening ma y relate to the duration and severity of disease and the degree of airflow obstruction.