Atrial fibrillation, CHA2DS2-VASc score, antithrombotics and risk of non-traffic-, non-cancer-related bone fractures: A population-based cohort study.

Background: Accidental bone fractures are a major cause of premature disabilities and death. Whether atrial fibrillation (AF) treated with or without antithrombotics correlates with occurrence of such events remains under-investigated.

Methods: Patients ≥18 years with newly diagnosed AF between 2005 and 2009 without previous cancers or traffic injury were identified from the "Longitudinal Health Insurance Database 2005" (1 million beneficiaries) of Taiwan's National Health Research Institutes and served as the AF group. A fourfold number of age-, gender-, and comorbidity-matched patients but without AF served as the non-AF controls. Patients were followed, and cumulative incidence of hospitalization-requiring bone fractures was compared between groups. Predictors of accidental bone fractures were determined by Cox regression analysis.

Results: Within a mean follow-up of 3.6 years, bone fractures, especially those involving neck/trunk and lower limbs, were significantly more frequent in patients with AF (N=6925) than in those without (N=27,700) (7.0 vs. 3.8 per 1000 person-years, log-rank p=0.001, adjusted HR=1.85, 95% CI=1.50-2.30, p<0.001). Cox models identified female gender, previous stroke, and CHA2DS2-VASc score≧1 as risk factors for bone fractures in AF patients, whereas oral anticoagulants (HR=0.62, 95% CI=0.35-0.91, p=0.034), especially when used in patients with CHA2DS2-VASc score≧1 but not antiplatelet therapy (p=0.39) as negative predictors.

Conclusion: Patients with AF are more vulnerable to non-traffic-, non-cancer-related bone fractures especially when with specified characteristics. For those with higher CHA2DS2-VASc scores, the use of anticoagulant but not antiplatelet agents could be associated with lower risk of such events.