Drug-associated acquired hemophilia A: an analysis based on 185 cases from the WHO pharmacovigilance database.

INTRODUCTION: Acquired hemophilia A (AHA) is a rare autoimmune hemorrhagic disease occurring in several underlying conditions. Drug-associated AHA (D-AHA) is poorly addressed nowadays.

AIM: This work aims to identify and characterize which drugs are associated with AHA using the WHO global database of reported potential effects of medicinal products (VigiBase).

METHODS: First, we realized a disproportionality analysis using the information component (IC) to identify D-AHA in VigiBase. IC compares observed- and expected-values in order to find associations between drugs and adverse drug reactions (ADRs) using disproportionate Bayesian reporting. IC025 is the lower end of a 95% credibility interval for the IC. Then, we collected cases of drugs significantly associated with AHA from July 2004 to November 2021.

RESULTS: 14 drugs with IC025 > 0 were identified representing a total of 185 cases. D-AHA occurred more frequently in men (59%) than women (41%). The median (min-max) age at onset was 75 years (8-98). The median [Q1-Q3] time to onset of D-AHA from the start of the suspected drug was 30 days [9.5-73.75] and 10% of cases resulted in a fatality. The drugs associated with the highest IC025 (IC025 > 2) were Clopidogrel, Alemtuzumab, Omalizumab. This study retrieved for the first time three usually used drugs (3/14) that exhibit a significant pharmacovigilance signal for D-AHA.

CONCLUSION: This worldwide pharmaco-epidemiologic study updates the list of the drugs associated with AHA. The clinician should be aware of these possible severe ADR, which might require larger epidemiological and pathophysiologic studies.