Compared with warfarin, the non-vitamin K antagonist oral anticoagulants (NOACs) rivaroxaban and apixaban were associated with a lower risk of osteoporosis in patients with atrial fibrillation, a retrospective cohort study in Taiwan suggests. "With the aging of the population globally, osteoporosis has become a major issue with considerable medical and socioeconomic burdens," Dr. Huei-Kai Huang of Hualien Tzu Chi Hospital in Taiwan noted in an email to Reuters Health. "As oral anticoagulants are commonly prescribed for older patients who are susceptible to both atrial fibrillation and osteoporosis, the risks of osteoporosis associated with the use of NOACs and warfarin constitutes a vital clinical issue." "Current clinical guidelines suggest that patients with moderate-to-severe mitral stenosis or a mechanical heart valve...receive warfarin rather than a NOAC (for stroke prevention)," he added. To avoid possible selection bias, the team performed a sensitivity analysis that excluded this population. "The results were still robust," he said. Dr. Huang and colleagues analyzed data from Taiwan's national health insurance database on all adults newly diagnosed with atrial fibrillation and treated with NOACs or warfarin between 2012-2015. Patients who received NOACs were categorized into rivaroxaban, dabigatran, and apixaban subgroups. As reported in the Journal of the American Heart Association, 17,008 patients (about 58% men) were included, with 8,504 each in the NOAC and warfarin cohorts. NOACs were associated with a lower osteoporosis risk than warfarin (adjusted hazard ratio, 0.82). Treatment duration had an effect. Specifically, the lower osteoporosis risk with NOACs became stronger in those with longer treatment duration. Further, significantly lower risks of osteoporosis were seen with rivaroxaban (aHR, 0.68) and apixaban (aHR, 0.38), but not with dabigatran (aHR, 1.04). Dr. Huang said, "As fractures are the most serious complication of osteoporosis, our team has further evaluated the fracture risk among the NOAC/warfarin users." The soon-to-publish paper shows a reduced fracture risk in patients treated with NOACs compared with warfarin, he noted. The team is currently investigating the effect of NOAC/warfarin use on the risks of dementia and metabolic diseases, he added. Interventional cardiologist Dr. Philip Green of Columbia University Medical Center in New York City commented in an email to Reuters Health, "This study is an important addition to the literature. Unless contraindicated, most cardiologists have moved to a NOAC-first strategy to to prevent thromboembolism in atrial fibrillation based on both efficacy and safety." "While shared decision making is paramount in both deciding to anticoagulate to prevent stroke in atrial fibrillation and which agent should be used, this study contributes to the growing body of evidence that the risks of warfarin justify its use as a second-line agent." —Marilynn Larkin Source
