October 17, 2012
New Anticoagulant May Make Risk-Scoring Systems
Less Relevant

Durham, NC—Current risk-scoring systems for tailoring anticoagulation treatment to individual patients may be less relevant when using the anticoagulant apixaban for patients with atrial fibrillation who have at least one risk factor for stroke.

That’s according to a new study published recently in The Lancet.

"With new oral anticoagulants, such as apixaban, we might not need risk scores to guide treatment decisions for stroke prevention in patients with atrial fibrillation. This may simplify how physicians make decisions and also improve patient care," said lead author Renato Lopes, MD, a Duke University Medical Center cardiologist.

Lopes pointed out that apixaban was overall safer than warfarin and appeared to cause less intracranial bleeding in those patients whose risk scores defined them as being at the highest risk of bleeding. “The benefits of apixaban are preserved regardless of the risk score used and regardless of the patient risk category,” he said.

Under current practice guidelines, either antithrombotic therapy with warfarin or with aspirin, which is less effective but has lower risk of bleeding, is used for patients with atrial fibrillation and one risk factor for stroke. Apixaban, an oral direct factor Xa inhibitor, better prevents stroke and has a lower risk of bleeding than warfarin, which may make it a more attractive option than aspirin for those patients, according to study authors.

The recent analysis used data from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial to assess safety and efficacy of apixaban versus warfarin in 18,201 patients based on the most popular risk assessment scoring systems: CHADS2, CHA2DS2VASc, and HAS-BLED.

According to the study, apixaban significantly reduced stroke or systemic embolism with no evidence of a differential effect by risk of stroke (CHADS2 1, 2, or ≥3, p for interaction = 0·4457; or CHA2DS2VASc 1, 2, or ≥3, p for interaction = 0·1210) or bleeding (HAS-BLED 0—1, 2, or ≥3, p for interaction = 0·9422). Patients who received apixaban had lower rates of major bleeding than did those who received warfarin, with no difference across all score categories (CHADS2, p for interaction = 0·4018; CHA2DS2VASc, p for interaction = 0·2059; HAS-BLED, p for interaction = 0·7127).

"Risk stratification has been a key element in identifying patients at risk for stroke and bleeding and in helping to guide antithrombotic treatment for patients with atrial fibrillation," Lopes said. "However, most of patients at high risk for stroke are also at high risk for bleeding. This makes the treatment of these patients a challenge in clinical practice.”

He added that “the current risk scores used in clinical practice for patients with atrial fibrillation may play less of a role in decision-making because we now have more efficacious and safer drugs."

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