Results of a large study indicate that patients with atrial fibrillation (AF) and a low risk of thromboembolism are sometimes prescribed oral
anticoagulants even though guidelines recommend against it.
“The irony is that there is a general push to get providers to prescribe these drugs, and they are also generally underprescribed among many AF
patients who actually need them,” said study author Gregory Marcus, MD, of the University of California San Francisco.
“Our study suggests people are trying to do the right thing but, due to a lack of understanding of some of the critical nuances, go too far in that direction in low-risk patients.”
Dr Marcus and his colleagues described this study in JAMA Internal Medicine.
The team noted that previous AF guidelines recommend against the use of oral anticoagulants in patients younger than 60 years of age without heart disease or other known risk factors for thromboembolism, and updated guidelines do not recommend the use of oral anticoagulants in patients without any established risk factor for stroke.
The researchers wanted to determine the frequency with which oral anticoagulant prescriptions are made outside of guideline recommendations. So they assessed 10,995 AF patients ages 60 and under from the overall Practice Innovation and Clinical Excellence (PINNACLE) Registry of the National Cardiovascular Data Registry who were treated in the US between 2008 and 2012.
About 23% (n=2561) of patients with a CHADS2 score of 0 and about 27% (n=1787) of patients with a CHA2DS2-VASc score of 0 were prescribed oral anticoagulant therapy contrary to guideline recommendations.
In a multivariable analysis of patients with a CHADS2 score of 0, several factors were associated with a higher likelihood of being prescribed oral anticoagulants. These included older age (relative risk [RR]=1.48 per 10 years; P<0.001), male sex (RR=1.34; P<0.001), higher body mass index (RR=1.18 per 5kg/m2; P<0.001), and having Medicare rather than private insurance (RR=1.32; P<0.001).
On the other hand, being treated in the South rather than the Northeast was associated with a lower likelihood of being prescribed oral anticoagulants (RR=0.69; P=0.04).
The researchers observed similar results in a multivariable analysis of patients with a CHA2DS2-VASc score of 0. Being treated in the South rather than the Northeast was associated with a lower likelihood of being prescribed oral anticoagulants (RR=0.67; P=0.03).
And older age (RR=1.44 per 10 years; P<0.001), higher body mass index (RR=1.19 per 5 kg/m2; P<0.001), having Medicare rather than private insurance (RR=1.29; P<0.001), and having no insurance rather than private insurance (RR=1.19; P=0.02) were all associated with a higher likelihood of being prescribed oral anticoagulants.
The researchers said these results suggest providers may not be fully aware of the potential risks of these drugs or the particularly low risk of thromboembolism in certain populations.
“Practitioners who prescribe blood thinners need to be diligent about weighing the risks and benefits of these medications,” said study author Jonathan C. Hsu, MD, of the University of California San Diego.
“In those patients with no risk factors for stroke, the risk of bleeding likely outweighs the benefit of stroke reduction. The fact that blood thinners were prescribed to so many patients with no risk factors for stroke is a wake-up call that we need to do better for our patients.”
