Bullous pemphigoid: three main clusters defining three outcome profiles
Background: Bullous pemphigoid (BP) is the most common autoimmune blistering disorder. Its presentation is polymorphic. Objective: To investigate different clinical and biological profiles of BP. Methods: We conducted a retrospective two-center study including all BP patients seen between January 1st, 2015 and February 28th, 2021. We performed hierarchical clustering on principal components. Results: Three clusters were identified. Patients in cluster 1 (n=155) were older than those of clusters 2 (n=89) and 3 (n=35, p<0.0001), more frequently presented pauci-bullous BP n=63 (41%) vs. 14 (16%) and 2 (6%) respectively, p<0.0001 and had anti-BP230 antibodies in 87% of cases. More than 100 blisters were observed in 14 patients (40%) from cluster 3, vs 3 (2%) of cluster 1 and 0 (0%) from cluster 2 (p<0.0001). Frequency of mucosal involvement was higher in cluster 3 n=32 (91%, including epiglottis in 40%) vs. 11 (7%) and 34 (38%), p<0.0001. In clusters 2 and 3, 70% and 74% of patients had antibodies targeting only BP180. Cluster 3 received more lines of systemic treatment and experienced more relapses. Limitations: Retrospective study without immunoelectron microscopy. Conclusion: We identified three different BP clusters, including one corresponding to severe BP180 + BP230 - BP with features common to mucous membrane pemphigoid.