BTN News: Patients with atrial fibrillation (AF) who use these doses appear to suffer more bleeding episodes than those on standard doses, according to a study that came to this surprising conclusion. According to study principal investigator Dr. Gualtiero Palareti from the Fondazione Arianna Anticoagulazione, Bologna, Italy, who published their results in Blood Advances on June 6, this research is variant to common assumptions that bleeding risk decreases with lower dosing.
They then followed 2,357 patients with AF (1,657 receiving standard doses and 700 low-dose DOACs). Fifteen to 30 days after initiation blood samples were collected and patients followed for one year and monitored for major and clinically relevant non-major bleeding events.
Key Findings and Statistics
After a median of 1,606 patient-years of follow up, clinicians recorded 50 bleeding events translating into a bleeding rate of 3.11% per patient-year. At the same time, we want to show that for those with a C-trough standardized activity level of more than 0.50 (the baseline value), 15 bleeding events were seen, corresponding to only a slightly higher rate of 4.97 percent per patient-year advantage over two class groups (35 events:2.69 percent per patient-year);
Treatment Initially and Risk of Bleeding
Most strikingly, the study identified a highly vulnerable window of time for patients that occurs during the first three months of treatment. During this phase were seen higher bleeding risk in patients, particularly those on low-dose DOACs. This found that low dose aspirin users were around twice as likely to fall into the highest class of activity, with activity values associated with an increased bleeding rate of 4.3 percent per patient-year in this group compared to 2.2 percent among patients on standard doses.
Clinical Practice Implications
In their study of AF patients Dr. Palareti and his team underscore the necessity of early determination of DOAC levels. The study discovered that a substantial number of patients, on low doses, were highly active and at risk of significant bleeding in the first few months after starting treatment. It seems counterintuitive, but so the routine monitoring and possibly modification of DOAC doses is probably paramount in reducing bleeding complications in AF patients.
Conclusion
The results of this study should lead to revisiting dosing strategies for DOACs in this population. Because low-dose DOACs are associated with significantly more bleeding than high-dose DOACs was already known, but finding that the higher risk of bleeding extended to low- and intermediate-dose aspirin is a new twist and is likely to reinforce physician efforts to maximize the balance between anticoagulant efficacy and safety. Additional studies should investigate the best dosing approach to maximize patient benefit, while minimizing toxic effects.
