Impact of relative contraindications on the use, benefits, and risks of anticoagulant prophylaxis in atrial fibrillation: analysis of a claims database

Background: Many individuals with atrial fibrillation (AF) do not receive recommended anticoagulant prophylaxis for stroke prevention. The study investigators attempted to assess whether the presence of relative contraindications (RCIs) to anticoagulation with warfarin might contribute to this, and to assess the risks and benefits of prophylaxis in patients with RCIs. Methods: Study investigators identified patients with established non-valvular AF and flutter in a claims database. Operationally defined RCIs included, in order of clinical severity: (1) prior intracranial hemorrhage; (2) gastrointestinal bleeding or esophageal varices; (3) neurological disorder; and (4) dizziness. Nonfatal events were attributed to warfarin if patients had an appropriate claim in the previous month. Results: A total of 67,082 AF patients were eligible for analysis, including 50,485 (75.3%) in the prevalent cohort. Warfarin exposure during the study period was 68% in the prevalent cohort. At baseline, 50.5% of prevalent cohort patients had one or more RCIs. Patients with RCI had higher prevalence of stroke risk factors (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, and prior stroke or transient ischemic attack) compared to those without RCI. Patients with RCIs often received warfarin and had lower rates of ischemic stroke than those who did not. Conclusions: These results suggest that RCIs do not account for underutilization of anticoagulant prophylaxis in AF patients. Further, the benefit/risk aspects of anticoagulation for stroke prophylaxis may be favorable for many patients with RCIs.