Dabigatran is Associated With a Lower Risk of Osteoporotic Fractures Compared to Warfarin

MedicalResearch.com Interview with:
Wallis CY Lau BSc

Centre for Safe Medication Practice and Research
Department of Pharmacology and Pharmacy
Li Ka Shing Faculty of Medicine
The University of Hong Kong

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Warfarin is a vitamin K antagonist (VKA) oral anticoagulant used for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF), a common heart rhythm disorder. It works by interfering with vitamin K-dependent reactions in the process of blood clot formation. As these reactions also play a role in bone mineralization, there is concern that warfarin use may be linked with osteoporotic fracture. Despite the concerns for fracture risk, warfarin had been an inevitable treatment choice for over 50 years as there were no other alternatives available.

Dabigatran is the first non-VKA oral anticoagulant (NOAC) approved for use in patients with NVAF. Recently, an animal study reported that use of dabigatran is associated with a better bone safety profile compared to warfarin in rats, suggesting a potential for a lower risk of osteoporotic fractures over warfarin. However, the actual risk of osteoporotic fractures with dabigatran use in human remains unclear. Therefore, we conducted a population-based cohort study to compare the risk of osteoporotic fractures in patients with NVAF treated with dabigatran and warfarin.

MedicalResearch.com: What are the main findings?

Response: We studied 8,152 patients with NVAF in Hong Kong and found that use of dabigatran was associated with a lower risk of osteoporotic fractures compared to warfarin (incidence 0.7 vs 1.1 per 100 person-years) during a mean follow-up of approximately 500 days. This observed lower risk was more pronounced among patients with a history of falls and/or fractures (incidence 1.6 vs 3.6 per 100 person-years).

MedicalResearch.com: What should readers take away from your report?

Response: Osteoporotic fracture is a key clinical concern because patients on oral anticoagulation are usually older people among whom fracture is a significant cause of morbidity and mortality. While surgery is usually required to treat a fracture, perioperative management of anticoagulation is challenging given the need to balance the reduction of stroke and excessive bleeding.

Our findings suggest that dabigatran is associated with a lower risk of osteoporotic fractures compared to warfarin. If this association is confirmed, dabigatran could serve as a safer alternative to warfarin for reducing the risk of osteoporotic fractures in patients with NVAF.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Response: Additional epidemiological and mechanistic studies are warranted to further investigate the effects of dabigatran on bone and the underlying mechanisms by which dabigatran may be associated with a lower risk of osteoporotic fractures compared to warfarin. Randomized clinical trials may be warranted as, if this association is confirmed, screening of patients with NVAF for the risk for osteoporotic fractures could be considered to inform the choice of oral anticoagulant prescribed in clinical practice.

MedicalResearch.com: Is there anything else you would like to add?

Response: Dabigatran is known to cause gastrointestinal bleeding. Our previous research showed that patients on gastroprotective medications were less likely to have gastrointestinal bleeding associated with dabigatran use. Therefore, it is important for clinicians to tailor the treatment regimen for patients with NVAF according to patients’ needs to minimize the adverse effects of anticoagulants.

Disclosures: This study received no funding support.

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Lau WCY, Chan EW, Cheung C, Sing CW, Man KKC, Lip GYH, Siu C, Lam JKY, Lee ACH, Wong ICK. Association Between Dabigatran vs Warfarin and Risk of Osteoporotic Fractures Among Patients With Nonvalvular Atrial Fibrillation. JAMA. 2017;317(11):1151-1158. doi:10.1001/jama.2017.1363

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