Women with atrial fibrillation (AFib) are significantly less likely to use oral anticoagulants (OAC), across all levels of the CHA₂DS₂-VASc risk score, according to a study published July 19 in the Journal of the American Heart Association.

Led by Lauren E. Thompson, MD, et al., the study used ACC’s PINNACLE Registry to analyze patients diagnosed with AFib between May 1, 2008 and Dec. 31, 2014. Of the 691,906 patients included in the analysis, 48.5 percent were women who were older and had a lower body mass index, a lower prevalence of coronary artery disease and a higher prevalence of many CHA₂DS₂-VASc risk factors.

Results found that while 59 percent of the study population was prescribed an OAC, women were less likely than men to use any OAC overall (56.7 percent vs. 61 percent; p < 0.001) and at all levels of the CHA₂DS₂-VASc score (adjusted risk ratio 9 percent to 33 percent lower; p value for each < 0.001). Overall OAC use increased for both sexes over the six-year study, with women seeing a slightly higher rate in non–vitamin-K OAC use than men (increase per year 56.2 percent vs. 53.6 percent) between 2010 and 2014. However, women remained less likely to receive any OAC throughout the study period.

Researchers note that “Despite the introduction of the CHA₂DS₂-VASc score and NOACs, a risk treatment paradox for OAC use in eligible women with AF[ib] persists. Our study suggest that female sex is underemphasized as a thromboembolic risk factor.”

They add, “Our findings suggest that sex differences in OAC use may be primarily due to differences in use of warfarin.” Highlighting the decrease of warfarin use and increase of NOAC use, they believe, “it is possible that if NOAC use continues to increase over time, sex differences in overall OAC use may decrease and eventually be eliminated.”

In conclusion, the study authors note that “Further studies are needed to understand whether lower rates of OAC use in women are associated with differences in clinical outcomes, and if so, action is needed to eliminated unnecessary differences in OAC use by sex.”

Keywords: Warfarin, Risk Factors, Atrial Fibrillation, Odds Ratio, Coronary Artery Disease, American Heart Association, Sex Characteristics, Prevalence, Body Mass Index, Research Personnel, Anticoagulants, Cytarabine, Registries

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