TABLE
Dabigatran vs warfarin: A look at the evidence1
| Event | Incidence (%/y) | NNT/NNH with dabigatran instead of warfarin | Relative risk (95% CI) | P value | |
|---|---|---|---|---|---|
| Dabigatran (150 mg) | Warfarin | ||||
| Stroke or systemic embolism | 1.11 | 1.69 | NNT: 173 | 0.66 (0.53-0.82) | <.001* <.001 |
| Hemorrhagic stroke | 0.10 | 0.38 | NNT: 477 | 0.26 (0.14-0.49) | <.001 |
| MI | 0.74 | 0.53 | NNH: 477 | 1.38 (1.00-1.91) | .048 |
| Death from any cause | 3.64 | 4.13 | NS | 0.88 (0.77-1.00) | .051 |
| Major bleeding | 3.11 | 3.36 | NS | 0.93 (0.81-1.07) | .31 |
| Intracranial bleeding | 0.30 | 0.74 | NNT: 228 | 0.40 (0.27-0.60) | <.001 |
| GI bleeding | 1.51 | 1.02 | NNH: 205 | 1.50 (1.19-1.89) | <.001 |
| Life-threatening bleeding | 1.45 | 1.80 | NNT: 286 | 0.81 (0.66-0.99) | .04 |
| CI, confidence interval; GI, gastrointestinal; MI, myocardial infarction; NNH, number needed to harm; NNT, number needed to treat; NS, no significant difference. *P value for noninferiority; all other P values are for superiority. | |||||
Mortality rates are similar
Rates of death from any cause were similar among the 3 treatment groups. The rates of hemorrhagic stroke were lower in both dabigatran groups compared with the warfarin group, while rates of MI were lower in the warfarin group than in either of the dabigatran groups.
Dyspepsia was the only other adverse effect that was significantly more common among dabigatran users vs warfarin users. Rates of hepatotoxicity, which was a problem wiThearlier oral direct thrombin inhibitors, were similar for both drugs. Multiple subgroup analyses revealed no significant interaction between the treatment effect of dabigatran and variables such as sex, body mass index, creatinine clearance, CHADS2 score, aspirin use, or previous long-term use of a vitamin K antagonist.
WHAT’S NEW: This easier-to-use oral anticoagulant is a viable option
Dabigatran gives physicians and patients with atrial fibrillation an option that is more convenient than warfarin for stroke prevention. Its 150-mg dose is more effective in preventing stroke compared with warfarin, and comparable in terms of bleeding risk.
CAVEATS: Unknown long-term effects, potential for bias
The median follow-up in the RE-LY study was 2 years. Longer-term efficacy and safety data may differ from the initial results.
The trial was funded by Boehringer Ingelheim, the manufacturer of dabigatran (Pradaxa). However, study coordination, data management, and analysis were performed independently by the Population Health Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Ontario, Canada.
Patients taking dabigatran received the medication in a blinded fashion, but the warfarin group could not be blinded because of the need for INR monitoring and dosage adjustments. To decrease potential bias, the outcome events were assessed by 2 independent investigators who were blinded to the treatment assignments.
CHALLENGES TO IMPLEMENTATION: Cost of dabigatran may be a barrier
The wholesale price of dabigatran, as quoted by Boehringer Ingelheim, is $6.75 per day; the retail price for a 30-day supply is approximately $235, according to drugstore.com, Walgreens, and Walmart). In comparison, a one-month supply of warfarin is about $15. Out-of-pocket costs for many patients will likely be high until dabigatran is added to insurers’ formularies. When costs for monitoring and hospitalizations or treatment for complications associated with warfarin are factored in, however, dabigatran is cost effective, a recent study indicates.7
Acknowledgement
The PURLs Surveillance System is supported in part by Grant Number UL1RR024999 from the National Center for Research Resources, a Clinical Translational Science Award to the University of Chicago. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health.