Concurrent use of Direct Acting Anticoagulants (DOACs) and antiplatelet medications appears to be common and confers a significantly increased risk of bleeding, an Australian study shows.
Clinicians in Victoria have called for deprescribing of antiplatelets in patients taking DOACs after they found a five-fold higher risk of major bleeding events in patients taking both classes of agent concurrently.
Their retrospective observational study of 203 patients being treated with anticoagulants during hospital admission in a general medicine unit at Eastern Health, Melbourne, found that 39 were taking antiplatelets, of whom only three had a guideline-recommended indication such as recent history of ACS.
Overall, more than one in ten patients (21) taking DOACs developed clinically significant bleeding event during a mean of 293 days of follow up, which translated into an incidence of 13.7 per 100 person years. The risk was four-fold higher in those taking concurrent antiplatelet therapy.
Major bleeding events were reported for 4% of patients, with an odds ratio of 5.07 in multivariate analysis for concurrent use of antiplatelets.
The only other predictor of bleeding events was older age (over 75) and there was no apparent association with anaemia or renal function.
The study authors, led by Dr Mahesan Anpalahan, said the bleeding risk seen with DOACs in the Victorian hospital setting was higher than that reported in clinical trials.
This might be because higher doses of antiplatelets are being used in the Australia real word setting (100-150mg/day) than in clinical trials (80mg), he suggested. Another reason might be that the study population also included a high proportion taking DOACs for VTE prevention (44%), which usually requires a higher dosing regimen of DOAC and therefore may predispose patients to a greater risk of bleed.
Most of the patients in the study population were taking rivaroxaban (63%), with other commonly used DOACs being apixaban (28%), and dabigatran (8.9%), respectively.
Writing in the Internal Medicine Journal, Dr Anpalahan acknowledged that the numbers in the study were small, but the findings confirmed those of other studies showing that concurrent use of DOACs and antiplatelet medications has a significant independent association with clinically significant bleeding events.
This observation suggests that, with due diligence in prescribing, the concurrent use of antiplatelet medications could potentially be avoided in a significant number of patients.
“Caution should be exercised when prescribing antiplatelet medications with DOACs as this combination is a potential risk factor for clinically significant bleeding events.”
“The concurrent prescription of antiplatelet medications with DOACs in the majority of patients appears discordant with the current consensus guidelines; therefore, deprescription of antiplatelet medications in the vast majority of these patients would be safe and may mitigate the excessive bleeding risk,” he concluded.