Mortality and prognostic factors in patients with bullous pemphigoid: a retrospective multicenter Italian study

Introduction: Bullous pemphigoid is the most common autoimmune bullous dermatosis. In recent years several studies have tried to identify the main factors of the disease related with an increased risk of death. The aim of this multicenter Italian study was to assess the risk score of death considering epidemiologic, clinical, immunological, and therapeutic factors in a cohort of patients affected by bullous pemphigoid and try to identify the cumulative survival up to 120 months. Methods: We retrospectively reviewed the medical records of patients with bullous pemphigoid who were diagnosed between 2005 and 2020 in the 12 Italian centers. Data collected included sex, age at the time of diagnosis, laboratory findings, severity of disease, time at death/censoring, treatment, and multimorbidity. Results: A total of 572 patients were included in the study. The crude mortality rate was 20.6%, with an incidence mortality rate of 5.9 × 100 person/year. The mortality rate at 1, 3, 5, and 10 years was 3.2%, 18.2%, 27.4% and 51.9%, respectively. Multivariate model results showed that the risk of death was significantly higher in patients older than 78 years, in presence of multimorbidity, anti-BP180 autoantibodies >72 U/mL, or anti-BP230 > 3 U/mL at diagnosis. The variables jointly included provided an accuracy (Harrel's Index) of 77% for predicting mortality. Conclusion: This study represents the first nationwide Italian study to have retrospectively investigated the mortality rates and prognostic factors in patients with bullous pemphigoid. A novel finding emerged in our study is that a risk prediction rule based on simple risk factors (age, multimorbidity, steroid-sparing drugs, prednisone use, and disease severity) jointly considered with two biomarkers routinely measured in clinical practice (anti-BP230 and anti-BP180 autoantibodies) provided about 80% accuracy for predicting mortality in large series of patients with this disease.