Safety and efficacy of direct oral anticoagulants in patients with anaemia and atrial fibrillation: an observational nationwide Danish cohort study

Aims The aim of this study was to evaluate the risk of stroke and bleeding among patients with atrial fibrillation (AF) treated with direct oral anticoagulants (DOACs) despite anaemia at treatment initiation time. Methods and results All Danish patients (N = 41 321) diagnosed with incident AF, having a baseline haemoglobin (Hb), and subsequently initiated DOAC therapy between 2012 and 2019 were identified through administrative registry databases. Patients with anaemia were subdivided according to the World Health Organization classification of anaemia and evaluated regarding risk of stroke and composite bleeding endpoint [hospitalization due to urogenital, gastrointestinal (GI), or intracranial bleeding or epistaxis]. Standardized absolute 1-year risks of stroke and composite bleeding endpoint were calculated using multivariable Cox regression analyses. The standardized absolute 1-year risk difference for composite bleeding increased by 0.96% [95% confidence interval (CI) 0.38-1.54] for patients with moderate/severe anaemia compared with patients with no anaemia. This risk was mainly driven by an increase in standardized absolute 1-year risk for serious GI bleeding, which increased by 0.41% (95% CI 0.19-0.63). No significant difference in standardized absolute 1-year bleeding risk was observed among patients with mild anaemia compared with patients with no anaemia 0.36% (95% CI -0.10 to 0.82). No significant difference in standardized absolute 1-year risk of stroke was observed among patients with mild anaemia, -0.16% (95% CI -0.13 to 0.15), and moderate/severe anaemia, -0.47% (95% CI -0.16 to 0.19), compared with patients with no anaemia. Conclusion For AF patients receiving DOACs, moderate/severe anaemia is a risk factor for serious GI bleeding, while stroke risk is the same regardless of whether anaemia was present at baseline or not.