Non-cystic fibrosis bronchiectasis (NCFB) is characterized by dilated bronchi, poor mucus clearance and susceptibility to bacterial infection. Pseudomonas aeruginosa (PA) is one of the most frequently isolated pathogens in patients with NCFB. The purpose of this study was to evaluate the association between presence of PA and disease severity in patients within the US Bronchiectasis and Nontuberculous mycobacteria (NTM) Research Registry (BRR).
Baseline US BRR data from adult patients with NCFB collected between 2008 and 2018 was used for this study. The presence of PA was defined as one or more positive PA cultures within two years prior to enrollment. Modified Bronchiectasis Severity Index (m-BSI) and modified FACED (m-FACED) were computed to evaluate severity of bronchiectasis. Unadjusted and multivariable multinomial regression models were used to assess the association between presence of PA and severity of bronchiectasis.
Average age of the study participants (n = 1831) was 63.7 years (SD = 14.1), 91.5% white, and 78.8% female. Presence of PA was identified in 25.4% of the patients. Patients with presence of PA had significantly lower mean pre-bronchodilator FEV1% predicted compared to those without PA (62.8% vs. 73.7%, p < .0001). In multivariate analyses, patients with presence of PA had significantly greater odds for having high (OR = 6.15 (95%CI:3.98-9.50) and intermediate (OR = 2.06 (95%CI:1.37-3.09) severity vs. low severity on m-BSI.
The presence of PA is common in patients with NCFB within the Bronchiectasis and NTM Research Registry. Severity of bronchiectasis is significantly greater in patients with PA which emphasizes high burden of the disease.

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