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DOACs linked to lower fracture risk versus warfarin in AFib patients



Among patients with atrial fibrillation, use of direct oral anticoagulants is linked to lower osteoporotic fracture risk versus warfarin, results of a recent population-based cohort study show.


The choice of direct oral anticoagulant (DOAC) didn’t appear to have an impact, as each individual agent yielded a substantially lower risk of fracture versus the vitamin K antagonist, with risk reductions ranging from 38% to 48%, according to the study authors.

This is one of the latest reports to suggest DOACs could have an edge over warfarin for preventing fractures, providing new evidence that “may help inform the benefit risk assessment” when it comes to choosing an anticoagulant for a patient with atrial fibrillation (AFib) in the clinic, wrote the authors, led by Wallis C.Y. Lau, PhD, with the University College London.

“There exists a compelling case for evaluating whether the risk for osteoporotic fractures should be considered at the point of prescribing an oral anticoagulant to minimize fracture risk,” Dr. Lau and coauthors wrote in a report on the study that appears in Annals of Internal Medicine.

The case is especially compelling since fracture risk is “often neglected” when choosing an anticoagulant, the authors wrote. Surgeries to treat fracture are difficult because of the need for perioperative management of anticoagulation as “a balance between the risk for stroke and excessive bleeding must be achieved,” they added.

Based on these data, physicians should strongly consider DOACs as an alternative to vitamin K antagonists to reduce the risk of osteoporosis over the long term in patients with AFib, according to Victor Lawrence Roberts, MD, a Florida endocrinologist.

“Osteoporosis takes years, sometimes decades to develop, and if you then overlay warfarin on top of a readily evolving metabolic bone disease, you probably accelerate that process, said Dr. Roberts, professor of internal medicine at the University of Central Florida, Orlando, and editorial advisory board member of Internal Medicine News.

There’s a considerable amount of concerning preclinical data that warfarin could increase osteoporotic fracture risk. Of note, vitamin K antagonists modulate osteocalcin, a calcium-binding bone matrix protein, Dr. Roberts said.

“Osteocalcin is important for bone metabolism and health, and inhibiting osteocalcin will inhibit the ability to have a healthy bone matrix,” he explained.

The impact of anticoagulants on fracture risk is particularly relevant to patients with AFib, according to Dr. Lau and colleagues, who referenced one 2017 report showing a higher incidence of hip fracture among AFib patients versus those without AFib.

In their more recent study, Dr. Lau and colleagues reviewed electronic health records in a Hong Kong database for 23,515 older adults with a new diagnosis of AFib who received a new prescription of warfarin or DOACs including apixaban, dabigatran, or rivaroxaban.

DOAC use was consistently associated with a lower risk of osteoporotic fractures versus warfarin, regardless of the DOAC considered. The hazard ratios were 0.62 (95% confidence interval, 0.41-0.94) for apixaban, 0.65 (95% CI, 0.49-0.86) for dabigatran, and 0.52 (95% CI, 0.37-0.73) for rivaroxaban versus warfarin, the report showed.

Head-to-head comparisons between DOACS didn’t yield any statistically significant differences, though the analyses were underpowered in this respect, according to the investigators.

“This study can only rule out more than a twofold higher or a 50% lower relative risk for osteoporotic fractures between individual DOACs,” they wrote. “However, any absolute risk differences were small and would likely be of minor clinical significance.”

The reduced risk of fracture for DOACs versus warfarin was consistent in men and women with AFib, suggesting that women may particularly benefit from DOACs, given that they have a higher risk of fracture than men, the investigators added.

The results of this study suggest yet another benefit of DOACs over warfarin in patients with AFib, according to internist Noel Deep, MD, who is the chief medical officer of Aspirus Langlade Hospital in Antigo, Wisconsin.

“The lower risk of osteoporotic fractures with DOACS, in addition to other advantages such as lower risk of intracranial bleeding, once- or twice-daily consistent dosing, no dietary restrictions, and no blood tests to regulate the dose might be another reason that physicians may favor them over warfarin in older individuals requiring anticoagulation,” Dr. Deep said in an interview.

Results of this and several other recent studies may help in recommending DOACs to internal medicine patients who have a diagnosis of AFib requiring anticoagulation, according to Dr. Deep, who is also a physician at Aspirus Antigo Clinic and a member of Internal Medicine News’ editorial advisory board. These include a 2019 U.S.-based study of more than 167,000 patients with AFib (JAMA Intern Med. 2019;180[2]:245‐253) showing that use of DOACs, particularly apixaban, were linked to lower fracture risk versus warfarin use. Similarly, a Danish national registry study also published in 2019 showed that the absolute risk of osteoporotic fractures was low overall and significantly lower in patients who received DOACs (J Am Coll Cardiol. 2019;74[17]:2150-2158).

Funding for the study came from the University of Hong Kong and University College London Strategic Planning Fund. The study authors reported disclosures related to Bayer, Bristol-Myers Squibb, Pfizer, Janssen, Amgen, Takeda, IQVIA, and others.

SOURCE: Lau WCY et al. Ann Intern Med. 2020 May 18. doi: 10.7326/M19-3671.

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