Objective: This study compares and contrasts the clinical features of non-cystic fibrosis bronchiectasis with 3 uncommon disorders known to be associated with bronchiectasis but with distinctly different underlying defined pathophysiologic derangements, namely severe alpha-1 antitrypsin deficiency (AATD), common variable immunodeficiency (CVI) and primary ciliary dyskinesia (PCD).
Methods: The Bronchiectasis Research Registry provides a central database for studying patients with non-cystic fibrosis bronchiectasis. This report consists of information from 13 U.S. sites pertaining to the 3 study diagnoses. Patients with AATD (SZ and ZZ phenotypes only), CVI (patients with IgG≤500), PCD (history of physician diagnosed Kartagener's syndrome or PCD), and patients with confirmed absence of the above 3 diagnoses (idiopathic control group) were included in the study. Descriptive statistics were computed for the main demographic and clinical characteristics of the sample stratified by group. Values between the groups were compared using Kruskal-Wallis test, and Chi-squared/ Fisher's exact tests respectively. The significance level was set at 0.05. Software SAS 9.4 was used to perform the statistical analyses.
Results: Of the 2170 participants in the database enrolled as of January 2017, 615 respondents had sufficient data and were included in the analyses. Patients with PCD (n=79, mean age 41.9 years [standard deviation (SD)=14.5]) were significantly younger than patients with AATD (n=58, mean age 66.9 [SD=10.7]), CVI (n=18, mean age 66.7 years [SD=10.5]) or the idiopathic group (n=460, mean age 64.2 [SD=15.9]), p<.0001. Compared to other groups, those with PCD had lower pulmonary function (forced expiratory volume in 1 second [FEV1] forced vital capacity [FVC] and FEV1/FVC ratio) (p<0.01), and a greater proportion of them reported having exacerbations and/or hospitalizations in the past 2 years (p<0.01). Overall, Pseudomonas aeruginosa and Staphylococcus aureus were the organisms most commonly isolated from sputum. Mycobacterial infection was most commonly reported in those with AATD.
Conclusion: This report from the U.S. Bronchiectasis Research Registry compares and contrasts differences in the clinical features of patients suffering from 3 rare conditions, with different underlying causes, to those without. The group with PCD had more symptoms, greater morbidity, lower lung function and more commonly were infected by Pseudomonas aeruginosa. A greater percentage of those with AATD reported mycobacterial lung involvement.
Keywords: Bronchiectasis Research Registry; alpha-1 antitrypsin deficiency; bronchiectasis; common variable immunodeficiency; primary ciliary dyskinesia.
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