Long-Term High-Flow Nasal Therapy in Patients with Bronchiectasis of Different Severity: A Retrospective Cohort Study

Background/Objectives: High-flow nasal therapy (HFNT) has been shown to reduce exacerbations of COPD and some evidence displays benefits in non-cystic fibrosis bronchiectasis (NCFB) patients. The present study aimed to compare the effectiveness of 12 months of home HFNT on the annual exacerbation rate between mild/moderate and severe NCFB patients, classified by the bronchiectasis severity index (BSI). Secondary outcomes were the evaluation of the dyspnea, pulmonary function, and sputum cultures in both groups. Methods: The study population included NCFB adult patients, with at least one severe exacerbation in the previous year on optimized therapy. NCFB exacerbations, dyspnea (mMRC score), pulmonary function test, and sputum cultures were assessed at baseline and after 12 months of HFNT. Results: A total of 86 NCFB patients were enrolled: 36 in the mild/moderate (BSI < 9) and 50 in the severe (BSI ≥ 9) group. A significant improvement in the annual exacerbation rate was found in both BSI ≥ 9 (p < 0.0001) and BSI < 9 cohorts (p < 0.0001), with a between-group difference of -1 (95% CI: -2 to 0) exacerbations per year (p = 0.0209). The change in the annual exacerbation rate was significantly correlated with BSI (ρ = -0.26, p = 0.0151) and with HFNT daily use (ρ = -0.22, p = 0.0460). The mMRC score significantly improved by -2 points (95% CI: -2 to -1) after treatment in both groups (p < 0.0001). The percentage of patients with P. aeruginosa colonization decreased from 34.9% to 27.9%. Conclusions: Long-term HFNT reduces the annual exacerbation rate in NCFB patients and its effectiveness increases alongside disease severity and daily use of HFNT.