F5 and antiphospholipid syndrome: Pharmacological prophylaxis was typically initiated within 23 hours in an RCT[33] and approximately 48 to 72 hours of admission in 3 observational studies[3,5]; and co-administration of mechanical prophylaxis in 3 other studies.[3,5,32] The exclusion criteria common in the included studies were hypercoagulable state (e.g., presence of antiphospholipid syndrome, factor V Leiden, protein C and S deficiencies, and active cancer) and a history of VTE within 6 months.