Included
- Age >18 years admitted under observation or inpatient status for acute VTE diagnosis (9/10-CM codes)
- Received ≥1 dose of apixaban or warfarin while admitted and continued the anticoagulant at discharge
Excluded
- Presence of mechanical heart valve
- Severe liver disease (defined as previous diagnosis of hepatic encephalopathy or esophageal varices)
- Pregnancy
- Taking a medication contraindicated for concomitant use with DOAC or warfarin therapy
