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In patients with atrial fibrillation (A-fib), treatment with the new factor Xa inhibitor apixaban results in fewer hospitalizations compared with aspirin. Results from a substudy of the AVERROES trial were published online July 25, 2013, ahead of print in the European Heart Journal.
For the AVERROES (Apixaban Versus Acetylsalicylic Acid to Prevent Strokes) trial, researchers enrolled 5,599 patients with A-fib at 522 centers worldwide who were at increased risk for stroke and were unsuitable for warfarin therapy. Subjects were randomized to receive apixaban (5 mg twice daily in the majority of patients) or aspirin (81-324 mg daily).
The trial was stopped early in May 2010 after an interim analysis revealed clear evidence of benefit with apixaban.
In the subanalysis, Stefan H. Hohnloser, MD, of Johann Wolfgang Goethe University (Frankfurt, Germany) and colleagues looked at hospitalization rates in those taking apixaban vs. aspirin. Over a mean follow-up of 1.1 years, the overall hospitalization rate for cardiovascular reasons was 14.3%. Hospitalizations, both cardiovascular and noncardiovascular, were lower in patients taking apixaban, as was the occurrence of stroke (table 1).
Table 1. Hospitalizations at 1.1 Years
Reason for Hospitalization
Apixaban(n = 2,808)
Aspirin(n = 2,791)
Percentages are expressed as X% per year.
Assignment to apixaban therapy was the only independent predictor of a reduced likelihood of the need for cardiovascular hospitalization (HR 0.81; 95% CI 0.70-0.93; P = 0.003). Age ≥ 75 years, higher CHADS2 score, and the need for cardiovascular hospitalization were independent predictors of mortality, with cardiovascular hospitalization carrying a fourfold increase in risk. Treatment with beta-blockers and antiarrhythmic drugs was associated with improved survival.
Reductions in Stroke Admissions Key
The main driver of the reduction in cardiovascular hospitalizations with apixaban was a reduction in admissions for stroke, particularly ischemic stroke (1.02% vs. 2.44%; P < 0.001). Interestingly, cardiovascular hospitalizations for causes other than stroke were also lower in the apixaban group, such as non-CNS systemic embolism (0.06% with apixaban vs. 0.38% with aspirin; P = 0.005).
“Finally, the risk for non-cardiovascular hospitalization was reduced by 15% in patients on apixaban,” the authors note. “We cannot explain with certainty the reduction in non-CV hospitalization, but it seems very likely that these results are, at least in part, explained by a reduction in stroke-related morbidities,” such as pneumonia, urinary and other infections, and pain syndromes, they continue.
In addition to reducing events such as strokes, non-CNS embolism, or congestive heart failure, the current data indicate that apixaban may also help lower A-fib-related health care costs, the authors add. “A relative risk reduction in cardiovascular hospitalizations of 20% as observed in AVERROES for apixaban would be reasonably expected to yield a significant reduction in health care expenses,” they point out.
Hospitalizations Vary by A-fib Type
Hospitalizations also were analyzed according to the type of A-fib. Annual rates of cardiovascular hospitalizations were 15.5% in patients with paroxysmal A-fib, 14.9% with persistent A-fib, and 12.5% in those with permanent A-fib (P = 0.02). The increased rate of admissions with paroxysmal A-fib was caused by more hospitalizations for treatment of A-fib (ie, cardioversion, antiarrhythmic drug therapy). There were more stroke hospitalizations in patients with persistent (2.23%) or permanent (2.44%) A-fib compared with paroxysmal A-fib (1.39%; P = 0.02 for overall trend). Hospitalizations for heart failure were more frequent in patients with permanent A-fib (4.4%) than in those with paroxysmal (1.62%) or persistent A-fib (2.78%; P < 0.001). Nevertheless, there was no significant interaction between the treatment effect of apixaban and the type of A-fib for any of the specific causes of hospitalization.