Aim To determine the relationship between the percentage of solids and both airway inflammatory markers and clinical outcomes in adults with stable bronchiectasis.

Methods A cross-sectional study enrolling adults with stable bronchiectasis was conducted. Sociodemographic, clinical data, patient-reported outcomes and exercise capacity were registered. Spontaneuos sputum samples were obtained to estimate the sputum concentration (percentage of solids) and the levels of airway inflammatory markers (mieloperoxidase, IL-8 and neutrophil elastase).

Results 27 participants were recruited. Most of the participants (n=11, 41%) were classified as severe following the Bronchiectasis Severity Index score. Table 1 summarises all outcome measures evaluated. The percentage of solids from the sputum samples were 5.5%[3.2-7.5] and 20 participants(74%) showed solids content values above 2%. A strong correlation was observed between the percentage of solids and neutrophil elastase concentration (r=0.66; p< 0.001), and moderate with mieloperoxidase (r=0.46;p=0.02) and IL-8 (r=0.57;p=0.03) levels. The Leicester Cough Questionnaire correlated moderately with neutrophil elastase concentration (r= - 0.51; p= 0.006). No other significant correlations were observed.

Conclusion A moderate-strong correlation was observed between the percentage of solids and airway inflammatory markers in adults with stable bronchiectasis.