Introduction The relationship between immunological biomarkers and evidence of lung damage has not been established in asthmatics that are sensitised to fungi. We sought to determine what features of allergic fungal airways disease were related to adverse radiological outcomes by the use of cluster analysis.
Method Factor analysis was used to determine the significance of different clinical and immunological variables, the number of clusters present and cluster membership (n = 423). The presence of radiological indicators of lung damage and inflammation were then assessed between these groups.
Results Three clusters were identified. Cluster 1 (37.1%) were obese, had late onset and minimal eosinophilic disease, cluster 2 (40.9%) had late onset eosinophilic disease and cluster 3 (22%) had early onset, atopic disease. Sensitisation to A. fumigatus was more prevalent in cluster 3 (94.2%; sIgE A. fumigatus 10.2 kUA/L (1.31–35.4)), compared to cluster 1 (44.9%; sIgE A. fumigatus 0.16 kUA/L (0.03–0.94)) and cluster 2 (45.7%; sIgE A. fumigatus 0.25 kUA/L (0.06–1.36)).
Cluster 3 had a greater degree of airflow obstruction (p < 0.001), bronchiectasis (69%, p < 0.001), tree in bud (32.4%, p < 0.001), collapse/consolidation (48.6%, p0.007) and fibrosis (31.7%, p < 0.05) than any of the other groups.
Conclusion This cluster analysis demonstrates that sensitisation to A. fumigatus, in addition to the other known clinical phenotypes, identifies asthmatics most at risk of developing fixed airflow obstruction and radiological features of airway inflammation and damage.