Study ObjectiveThe U.S. Food and Drug Administration approval of the use of apixaban in patients with a creatinine clearance (CrCl) of < 15 ml/minute or in those receiving dialysis is based only on pharmacokinetic data as clinical trials of apixaban excluded patients with a CrCl of2.5 mg/dl. Thus, the objective of this study was to evaluate the safety and effectiveness of apixaban versus warfarin in patients with severe renal impairment. DesignRetrospective, matched-cohort study. SettingCommunity hospital. PatientsA total of 146 adults who received at least one dose of apixaban (73 patients) or warfarin (73 patients) while hospitalized between January 30, 2014, and December 31, 2015, and had a CrCl of2.5 mg/dl, or who received peritoneal dialysis or hemodialysis, were included. Patients who were taking warfarin and had a therapeutic international normalized ratio on admission were matched consecutively in a 1:1 fashion in chronologic order to patients taking apixaban based on renal function and indication for anticoagulation. Measurements and Main ResultsThe primary outcome was major bleeding. Secondary outcomes included the composite of bleeding (major bleeding, clinically relevant nonmajor bleeding, and minor bleeding) in addition to documented ischemic stroke or recurrent venous thromboembolism. A nonsignificant difference in the occurrence of major bleeding and composite bleeding was observed between patients who received apixaban compared with those who received warfarin (9.6% vs 17.8%, p=0.149, and 21.9% vs 27.4%, p=0.442, respectively). The occurrence of stroke was similar between the groups (7.5% in each group), and no recurrent venous thromboembolism events were noted in either group during the study period. ConclusionApixaban appears to be a reasonable alternative to warfarin in patients with severe renal impairment.