Bleeding Risk Following Systemic Fluconazole or Topical Azoles in Patients with Atrial Fibrillation on Apixaban, Rivaroxaban, or Dabigatran

Background: Bleeding safety in relation to use of systemic fluconazole and topical azoles among patients with atrial fibrillation treated with apixaban, rivaroxaban, or dabigatran is insufficiently explored, despite clinical relevance and several reports suggesting associations. Methods: Using nationwide Danish registers, we identified patients with atrial fibrillation initiated on apixaban, rivaroxaban, or dabigatran from 2012-2018. We investigated associations between bleeding incidents and systemic fluconazole or topical azole treatment using a case-crossover design with 30-day exposure windows and reported odds ratios (OR) with 95% confidence intervals (CI). Results: We included 32,340 (36%), 32,409 (36%), and 24,940 (28%) patients initiated on apixaban, rivaroxaban, and dabigatran, respectively. Patients on apixaban were older (median age: 77 years; interquartile range [IQR] 70-84) compared with rivaroxaban users (median age: 75 years; IQR 68-82) and patients on dabigatran (median age: 73 years; IQR 66-80). Apixaban users had a significantly increased risk of bleeding following exposure to systemic fluconazole: odds ratio (OR) 3.5; 95% confidence interval (CI), 1.4-10.6. No increased risk was found among rivaroxaban and dabigatran users: ORs of 0.9 (95% CI, 0.2-3.0) and 1.7 (95% CI, 0.5-5.6), respectively. As to bleeding risk pertaining to topical azole exposure among apixaban, rivaroxaban, and dabigatran users, no association was found, with corresponding ORs of 0.8 (95% CI, 0.5-1.3); 1.3 (95% CI, 0.9-2.1); and 1.2 (95% CI 0.8-1.8), respectively. Conclusion: In patients with atrial fibrillation on either apixaban, rivaroxaban, or dabigatran, an association between an elevated bleeding risk and use of systemic fluconazole was found among patients on apixaban. We found no increased risk of bleeding following co-exposure to topical azoles.