Prevalence and Impact of Bronchiectasis in α1-Antitrypsin Deficiency

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Abstract
Rationale: α1-Antitrypsin (AAT) deficiency is associated with increased risk of chronic obstructive pulmonary disease (COPD), in particular emphysema, but airway disease is less well described. Objectives: To assess the prevalence of airways disease in subjects with AAT deficiency and to identify the relationship between radiological airway abnormalities and clinical phenotype. Methods: We characterized the computed tomographic phenotype of 74 subjects (PiZ), using visual scoring of airway disease and densitometric assessment of emphysema. Computed tomographic measurements were related to physiology, health status (St. George's Respiratory Questionnaire), and emphysema severity, and the relative impact of airway disease and emphysema severity on health status and airflow obstruction was compared by stepwise regression. Measurements and Main Results: Bronchiectatic changes were seen in 70 subjects, and a subgroup with a bronchiectasis-predominant phenotype was identified. Clinically significant bronchiectasis (radiologic bronchiectasis in 4 or more bronchopulmonary segments together with symptoms of regular sputum production) occurred in 20 subjects (27%). AAT-deficient index cases had higher airway disease scores (P < 0.05), more severe emphysema (P < 0.001), and greater impairment of physiology (P < 0.001) and health status (P < 0.05) than nonindex cases. Airway disease scores correlated with health status, and bronchial wall thickening correlated with FEV1. Regression analysis indicated that emphysema severity had the strongest associations for health status (r = 0.505, P < 0.001) and FEV1 (r = 0.699, P < 0.001), but the addition of airway disease score improved the regression models (r = 0.596, P = 0.002 and r = 0.783, P < 0.001, respectively). Conclusions: Emphysema is the predominant component of COPD in AAT deficiency, but the prevalence and impact of airway disease are greater than currently recognized. Consequently, future therapeutic strategies in AAT deficiency should also target this component of COPD.

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