The Significance of IgG to Aspergillus in Non-Cystic Fibrosis Bronchiectasis

Background: Aspergillus lung disease may be associated with either the development of, or complicate, non-cystic fibrosis bronchiectasis (NCFB). Whilst IgE to aspergillus may support a diagnosis of Allergic Bronchopulmonary Aspergillosis, the significance of IgG to aspergillus (IgG asp) in NCFB is unclear. Method: A retrospective case series reviewing 102 patients diagnosed with NCFB, seen in a specialist secondary care bronchiectasis clinic in 2015. 60.8% had a previous IgG asp performed. 16 (25.8%) patients had elevated (≥40mgA/L) IgG asp (high group) and 46 (74.2%) patients had normal (<40mgA/L) IgG asp (normal group). Spirometry results, hospital admissions per year, sputum results and CT imaging reports (CT thorax or high-resolution CT) were reviewed. Results: There was no significant correlation (Spearman rho) between IgG asp and FEV1 (% predicted) (Rs = -0.058, p<0.50). There was no significant difference in FEV1 (% predicted) between normal and high IgG aspergillus groups using independent T-test (p=0.797). There was no difference in the numebr of hospital admissions with an exacerbation of bronchiectasis in a 5 year period between the normal and high groups (independent T-test, p=0.297). Chi Square test showed no difference in the normal or high groups with either the presence of pseudomonas in sputum (p=0.10) or features that can be attributable to aspergillus infection on CT (p=0.694). Conclusion: This series suggests in patients with NCFB, IgG asp does not correlate with or relate to disease exacerbations, disease severity, spirometry decline or infection rates. This highlights the challenge clinicians’ face with assessing the clinical impact of aspergillus in NCFB.