Dabigatran Is an Effective Alternative to Warfarin in Elderly Patients

A large retrospective analysis from Canada suggests that dabigatran is about as safe and effective as warfarin in elderly patients with atrial fibrillation (AF).

Citing a general lack of real-world evidence concerning the novel oral anticoagulant’s effects in people aged 75 years and older, investigators used administrative databases to monitor outcomes for AF patients in Quebec who used warfarin or dabigatran between 1999 and 2013. The total study cohort included 15,918 dabigatran users and 47,192 similar warfarin users.

The researchers then focused on the 67.3% of patients who were 75 or older, and, after using propensity score adjusted models to control for potential differences between the study and control groups, found that dabigatran users, regardless of whether they took the 110mg or 150mg dose, faced roughly the same risk of stroke as warfarin users (hazard ratio [HR], 1.05; 95% confidence interval [CI], 0.93-1.19).

Dabigatran was associated with significantly lower rates of intracranial hemorrhage than warfarin (HR, 0.60; 95 % CI, 0.47—0.76). However, it was also associated with significantly higher rates of gastrointestinal bleeding (HR, 1.30; 95 % CI, 1.14–1.50).

“Based on real-life experience, dabigatran can offer an alternative to warfarin in elderly patients, with fewer intracranial bleeding events. However caution is warranted for gastrointestinal bleeding,” the study authors wrote in Thrombosis and Haemostasis.

The new study is the latest analysis of large patient groups to find that novel oral anticoagulants are safe and effective in elderly patients.

A meta-analysis that was published last year in the Journal of the American Geriatrics Society, for example, found that novel oral anticoagulants protected elderly AF patients against stroke at least as well as warfarin without producing any more bleeding.

That study pulled data on 25,031 elderly patients from 10 randomized controlled trials (RCTs) of different novel oral anticoagulants. The risk of major bleeding — or any form of clinically relevant bleeding — was roughly the same for study patients who used the newer medications and controls who used warfarin (odds ratio [OR], 1.02%; 95% CI, 0.73-1.43). In trials of patients with AF, the novel oral anticoagulants were more effective than conventional therapy in the prevention of stroke and systemic embolism (3.3% vs 4.7%; OR, 0.65; 95% CI, 0.48—0.87; absolute risk reduction [ARR],1.4%; number needed to treat [NNT], 71). In trials of patients with other conditions, the use of novel oral anticoagulants was associated with lower rates of venous thromboembolism (VTE) and VTE-related death than traditional therapies (3.7% vs 7.0%; OR, 0.45; 95% CI, 0.27–0.77; ARR, 3.3%; NNT, 30).

Prior research had been nearly unanimous in finding that new medications worked as well as warfarin in elderly AF patients, but a number of smaller studies had raised concerns about safety. The most publicized of those was probably a 2-month audit by the Haematololgy Society of Australia and New Zealand that found 78 episodes of dabigatran bleeds and identified participant age as 1 of 4 contributing factors.

“One of the major arguments for the findings was that the mean age of the trial population was low (71), and data from that trial may not be extrapolated into clinical practice,” wrote the meta-analysis authors, who believe their work nullified that argument. “The current analysis for individuals aged 75 and older, including data from 10 RCTs, did not show excess bleeding with novel oral anticoagulants or with dabigatran specifically (data pooled from 2 RCTs)…

“Almost all previous articles reporting greater bleeding in elderly adults included individuals who had comorbidities, mainly coexisting renal failure, but all of the reports were from small observational studies or case reports, and no randomized data are available. A possible explanation for the contrasting results of the current study might be that the chances of bleeding with novel oral anticoagulants are more related to associated comorbidities than the age of the individual per se.”