Microbiological Factors and Patient-Reported Outcomes of Exacerbation Burden in Pseudomonas aeruginosa-Colonised Bronchiectasis: A One-Year Prospective Study

Background: Exacerbations are key determinants of disease progression and impaired health-related quality of life (HRQoL) in non-cystic fibrosis bronchiectasis (BE). Despite the recognised association between Pseudomonas aeruginosa (PA) and worse outcomes, factors driving exacerbation burden remain poorly characterised. In patients with PA-colonised BE, we aimed to assess whether microbiological factors, including colonisation status and PA phenotype, together with HRQoL domains and respiratory symptoms, were associated with time to first exacerbation, exacerbation severity, and post-exacerbation changes in HRQoL. Materials and Methods: This prospective longitudinal study followed PA-colonised BE adults for 12 months with quarterly stable-state assessments focussing on time and severity of first exacerbation. HRQoL was measured by the Quality of Life Questionnaire-Bronchiectasis (QOL-B). Multivariable Cox, Firth penalised logistic, and ANCOVA models were fitted in R. Results: A total of 68 patients were included. During follow-up, 52 patients (76.5%) experienced ≥1 exacerbation, including 14 (26.9%) whose first event required hospitalisation. Neither colonisation status nor PA phenotype were associated with exacerbation risk or hospitalisation. Better daytime cough (HR 0.63, 95%CI 0.41–0.97; p = 0.036) and dyspnoea while talking (HR 0.47, 95%CI 0.26–0.87; p = 0.016) were independently associated with lower exacerbation risk. Lower exertional dyspnoea burden (OR 0.29, 95%CI 0.10–0.67; p = 0.003) and lower sputum quantity (OR 0.46, 95%CI 0.19–0.93; p = 0.030) were associated with lower odds of hospitalisation, together with poorer Vitality, Social Functioning, and Health Perceptions. After exacerbation, Social Functioning declined significantly (Δ −7.50 points, 95%CI −14.87 to −0.14; p = 0.046) and mucoid PA was independently associated with worse Emotional Functioning (β −15.64, 95%CI −27.89 to −3.39; p = 0.013). Conclusions: In PA-colonised BE, selected respiratory symptoms and HRQoL domains were associated with exacerbation burden, whereas microbiological characteristics showed no clear associations with exacerbation risk or hospitalisation, supporting the incorporation of patient-reported outcomes into longitudinal assessment.