Exacerbation Burden and Peripheral Airway Dysfunction as Determinants of Quality of Life in Bronchiectasis: Insights from Impulse Oscillometry.

Background and Objectives: Health-related quality of life (HRQoL) is a key outcome in bronchiectasis, reflecting the multidimensional burden of the disease. While exacerbation frequency is known to influence patient-reported outcomes, the contribution of peripheral airway dysfunction remains less clearly defined. Impulse oscillometry (IOS) provides a sensitive assessment of small airway resistance, but its relationship with HRQoL in bronchiectasis has not been fully explored. Materials and Methods: We conducted a cross-sectional observational study including 85 consecutive adults with non-cystic fibrosis bronchiectasis attending a second-level outpatient clinic. Clinical data, exacerbation history, radiological severity, lung function, inflammatory markers, and oscillometric parameters were collected. Peripheral airway resistance was assessed using the R5-R20 parameter derived from IOS. HRQoL was evaluated using the Quality of Life-Bronchiectasis (QoL-B) questionnaire. Associations between QoL-B score and clinical, functional, and inflammatory variables were explored using Spearman correlation and univariate linear regression. Variables with significant associations were entered into a multivariable linear regression model. Results: Patients had a median QoL-B score of 61.5 (IQR 55.5-80.0). Peripheral airway resistance (R5-20) was significantly associated with worse HRQoL in univariate analysis (β = -42.71; 95% CI -83.09 to -2.33; p = 0.038). Exacerbation frequency showed a strong inverse association with QoL-B (β = -5.74; 95% CI -8.60 to -2.89; p < 0.001). In multivariable analysis, exacerbations remained independently associated with poorer QoL (β = -5.365; p = 0.001), whereas the association with R5-20 was attenuated and no longer statistically significant. Conclusions: Peripheral airway dysfunction is associated with impaired HRQoL in bronchiectasis, but exacerbation burden appears to be the dominant independent determinant. These findings support the complementary role of oscillometry and clinical assessment in understanding patient-reported outcomes in bronchiectasis.