Klin Farmakol Farm. 2025;39(3):134-140 | DOI: 10.36290/far.2025.054

Adverse effects of oral anticoagulant therapy in hospitalized patients

Orsolya Hrubá¹, Lucia Žigová¹, Peter Jackuliak², Juraj Payer², Ján Kyselovič^{2, 3}, Andrea Gažová¹

¹ Ústav farmakológie a klinickej farmakológie, LF UK, Bratislava

² V. interná klinika LF UK a UNB, Bratislava

³ Katedra farmakológie a toxikológie, Univerzita veterinárneho lekárstva a farmácie, Košice

Aim of the study: To retrospectively evaluate the incidence of adverse effects of oral anticoagulant therapy (warfarin vs. direct oral anticoagulants - DOACs) in hospitalized patients who died during their hospital stay in a selected clinical department, with an emphasis on analyzing INR values, antidote administration, and the nature of clinical complications.

Methods: Between 2010 and 2022, a total of 46,521 hospitalizations were recorded at the 5th Department of Internal Medicine, Faculty of Medicine, Comenius University, and University Hospital Bratislava. Among these, 5,380 ended with the patient's death. Out of these, 461 patients were identified as having been treated with oral anticoagulants in their medication history (219 with warfarin, 242 with DOACs). Based on software-supported analysis of data, we evaluated demographic data (age, sex), length of hospital stay, laboratory values (INR), bleeding events, and antidote administration. Differences between the groups were assessed using the t-test or non-parametric tests, and the chi-square test (p < 0.05).

Results: Patients on DOACs were on average older (81.0 ± 8.3 vs. 78.5 ± 8.3 years; p < 0.05) and had a longer hospital stay (8.8 ± 9.5 vs. 7.1 ± 7.8 days; p < 0.05). In the warfarin group, there was a more pronounced fluctuation of INR (max. 23.37) and a higher incidence of complications defined as bleeding or extreme INR values (40.2 % vs. 6.6 % in the DOAC group), which more often required administration of vitamin K or prothrombin complex.

Conclusions: In the studied cohort of patients, the incidence of adverse effects appeared to be lower with DOACs compared to warfarin. Warfarin remains indispensable in certain indications, yet DOACs are emerging as a more suitable alternative for elderly polymorbid patients, even considering the limitations of safety assessment through INR. These observations align with the available literature, which indicates a lower incidence of bleeding and other adverse effects with DOACs, particularly among older patients with multiple comorbidities.

Keywords: anticoagulants, warfarin, DOAC, INR, bleeding.

Accepted: October 23, 2025; Published: October 30, 2025  Show citation