Bleeding Complications in Vancomycin-Induced Thrombocytopenia: A Real-world Postmarketing Pharmacovigilance Analysis

Purpose: Vancomycin and linezolid are first-line drugs used for the prophylaxis and treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Vancomycin is well known as the best alternative drug when linezolid-induced thrombocytopenia occurs. However, several cases with vancomycin-induced thrombocytope-nia, especially with bleeding complications, have been reported recently, which has attracted attention. The objective of this study is to assess the potential relevance between vancomycin and bleeding complications in thrombocytopenia. Methods: This is a real-world pharmacovigilance study conducted in October 2022 using the US Food and Drug Administration Adverse Event Reporting System (FAERS) database. We performed a disproportional analysis to assess the risk of bleeding complications in vancomycin-induced thrombocytopenia by calculating reporting odds ratios (RORs) and information components (ICs), with a weak signal defined as a lower limit of the IC 95% CI of 0 to 1.5, a middle signal defined as a lower limit of the IC 95% CI of 1.5 to 3.0, and a strong signal defined as a lower limit of the IC 95% CI of > 3.0. Findings: There were 21,854 cases in the FAERS database that listed vancomycin as a suspected drug from quarter 1 of 2004 to quarter 2 of 2022. There were 800 cases of vancomycin-induced thrombocytopenia and 125 cases of bleeding complications in vancomycin-induced thrombocytopenia. Teicoplanin, tigecycline, and vancomycin (3 middle signals) were sequentially less associated with thrombocytopenia than linezolid (strong signal). However, bleeding complications in thrombocytopenia were significant associated with vancomycin (ROR = 9.641; 95% CI, 8.105-11.468; IC = 3.184; 95% CI, 2.929-3.440 [middle signal]), followed by linezolid (ROR = 9.350; 95% CI, 7.318-11.947; IC = 3.106; 95% CI, 2.745-3.466 [middle signal]), teicoplanin (ROR = 6.399; 95% CI, 2.869- 14.272; IC = 2.059; 95% CI, 0.881-3.283 [weak signal]), and daptomycin (ROR = 2.784; 95% CI, 1.496-5.180; IC = 1.287; 95% CI, 0.374-2.201 [weak signal]). Tigecycline and daptomycin were the least likely anti-MRSA drug to cause thrombocytopenia (middle signal and weak signal, respectively) and bleeding complications in throm-bocytopenia (no signal and weak signal, respectively). Middle signals of bleeding complication in vancomycin-induced thrombocytopenia were found in all group except those < 45 to >= 80 years of age (weak signal). Implications: Bleeding complications in thrombocytopenia were significantly associated with vancomycin use, and the risk was highest among all the anti-MRSA drugs. Physicians should be aware of this possible serious adverse reaction.