Table 3:

Extended Outpatient VTE Chemoprophylaxis – Summary of evidence and considerations for practice

Study	Study Design	Summary of Evidence	Considerations for Practice
Incidence of VTE following discharge			• Following total hip or knee replacement, extended duration chemoprophylaxis is supported by the literature. • Data extrapolating these results to the trauma population are lacking, but there is strong evidence that the risk for VTE in trauma extends beyond hospital discharge. • LMWH, aspirin, and direct oral anticoagulants have shown promise for extended duration chemoprophylaxis of VTE, however the ideal agent to reduce VTE without increasing bleeding has yet to be determined. • Duration of VTE chemoprophylaxis following hospital discharge should likely be at least 4 weeks, but in some high-risk patients may extended as long as 3 months (or longer).
Olufajo 2016	Large retrospective database analysis	TBI patients in the California Office of Statewide Health Planning and Development Discharge (OSHPD) database had a 1.31% incidence of VTE during index admission, rising to 2.83% by one-year post-injury.
Godat 2015	Large retrospective database analysis	Trauma patients in the OSHPD database had a 3.97% incidence of VTE, 45.5% of which were diagnosed after initial admission.
Evidence supporting extended duration chemoprophylaxis
Bergqvist 1996	Prospective, randomized control	Patients undergoing total hip replacement received LMWH during their hospital stay and were randomly assigned to LMWH or placebo following discharge. There were significantly fewer VTE in the LMWH group vs control (24% vs 7%, p<0.001).
Shaikh 2020	Systematic review, meta-analysis	Reduced VTE incidence in surgical patients receiving extending chemoprophylaxis as compared to those who did not (4.36% vs/ 12.23%, p=0.006).
Knoll 2021	Systematic review, meta-analysis	Extended duration prophylaxis after abdominopelvic cancer surgery may reduce clinical VTE (1% vs 2.1%, relative risk (RR) 0.48, 95% CI 0.31–0.74) without increasing bleeding events.
Assessment of agents used for extended prophylaxis
Eriksson 2007	Prospective randomized control	Assessed two difference doses of dabigatran daily vs. enoxaparin daily for total hip arthroplasty. No difference in overall VTE or death between the three groups, and no difference in major bleeding.
Eriksson 2008	Prospective, randomized control	Daily rivaroxaban was found to reduce total VTE more effectively than daily LMWH after total hip replacement (0.2% vs 2%, p<0.001).
Lassen 2008	Prospective, randomized control	Daily rivaroxaban was found to reduce total VTE more effectively than daily LMWH after total knee replacement (1% vs 2.6%, p=0.005).
Raskob 2012	Pooled data meta-analysis	Twice daily extended duration apixaban demonstrated reduced VTE incidence following total knee or hip replacement compared to daily LMWH (0.7% vs 1.5%, p=0.001).
Anderson 2013	Prospective, randomized control	Following total hip replacement, patients were given LMWH or aspirin for 28 days following discharge without a significant difference in rates of either VTE or major bleeding.
Haac 2020	Prospective, randomized control	Patients with pelvic or extremity fractures were given either LWMH twice daily or aspirin twice daily upon discharge. No difference in efficacy was observed.
Matharu 2020	Systematic review, meta-analysis	Assessed aspirin in comparison to other anticoagulants for extended prophylaxis after total hip and knee replacement. Aspirin found to be non-inferior to other anticoagulants in the prevention of VTE.
Beauchamp-Chalifour 2022	Two center, retrospective cohort	Looked at elderly hip fracture patients and found that those treated with DOACs (as opposed to LMWH) for extended prophylaxis had a significantly higher risk of bleeding (OR 2.8 [1.5–5.0]).
Duration of post-discharge VTE prophylaxis
Godat 2015	Large retrospective database analysis	In OSHPD database, VTE rates were highest 3 months after injury (10.28%), dropped to 0.54% by 6 months, and 0.25% by 12 months (nearly the baseline population risk).
Ploumis 2009	Consensus Survey	Survey of 25 orthopedic and neurosurgical spine surgeons was conducted. Three months was the group consensus regarding duration of pharmacologic VTE prophylaxis after spinal cord injury.