A new analysis of a clinical trial suggests that higher blood levels of the blood thinner edoxaban may be linked to a greater risk of major bleeding in very old patients with atrial fibrillation. The study focused on 427 Japanese patients aged 80 years or older who had a high risk of bleeding. All were part of the ELDERCARE-AF trial, which compared a low dose of edoxaban (15 mg once daily) to a placebo.
Researchers measured edoxaban levels in the blood and divided patients into four groups from lowest to highest. They found that major bleeding occurred more often in patients with higher drug levels: about 0.8% per year in the lowest group, rising to 4.7% per year in the highest group. They also looked at a clotting test called prothrombin time (PT). Patients with a PT longer than 13 seconds had a higher rate of major bleeding (4.61% per year) compared to those with a shorter PT (0.98% per year).
It is important to note that this was a post hoc analysis, meaning the researchers looked back at data after the trial was over. This type of analysis can find associations but cannot prove that higher drug levels cause bleeding. The findings are also limited to very old Japanese patients and may not apply to other groups.
For now, the results suggest that monitoring PT might help identify very old patients at higher risk of bleeding while on edoxaban. However, no changes to clinical practice should be made based on this single analysis. Patients should continue taking their medications as prescribed and discuss any concerns with their doctor.
