Cost-effectiveness of rivaroxaban in the prevention of venous thromboembolism: A Canadian analysis using the Ontario Ministry of Health Perspective

Incremental net monetary benefit of direct oral anticoagulants for the prevention of venous thromboembolism after total knee or hip replacement: A systematic review and meta-analysis

INTRODUCTION

This meta-analysis was conducted to quantitatively pool the incremental net benefit (INB) of using direct oral anticoagulants (DOACs) for the prevention of venous thromboembolism (VTE) in patients undergoing total knee or hip replacements (TKR or THR).

MATERIALS AND METHODS

We performed a comprehensive search in several databases published before June 2021. Studies were included if they were cost-effectiveness analyses reporting cost per quality-adjusted life-year or life-year of DOACs compared to low molecular-weight heparins (LMWHs) or other anticoagulant agents for the prevention of VTE after TKR or THR. Risk of bias was also assessed using the biases in economic studies (ECOBIAS) checklist. Various monetary units were converted to purchasing power parity, adjusted to 2020 US dollars. The INBs were pooled across studies using a random-effects model, stratified by high-income countries (HICs) and low- and middle-income countries (LMICs). Heterogeneity was assessed using the I² statistic.

RESULTS

A total of 49 comparisons (TKR = 25 and THR = 24) from 16 studies was included. In HICs, DOACs were cost-effective compared to LMWHs from the health care system/payer perspective for the prevention of VTE after both TKR and THR with corresponding INBs (95 % CI; I²) of $231.91 ($178.71, $285.11; 0 %) and $254.99 ($159.20, $350.77; 27.79 %), respectively. In LMICs, DOACs were not cost-effective compared to LMWHs for both TKR and THR with the INBs of $94.13 (-$40.21, $228.47; 97.04 %) and $80.55 (-$157.37, $318.47; 99.78 %), respectively. No evidence of small-study effects was identified in any analyses. The cost-effectiveness of using DOACs for TKR and THR in HICs was robust across a series of sensitivity analyses.

CONCLUSIONS

DOACs were cost-effective as compared to LMWHs for VTE prophylaxis following TKR and THR surgeries in HICs. Further studies from LMICs are warranted.

Cost-effectiveness of Single vs Double Debridement and Implant Retention for Acute Periprosthetic Joint Infections in Total Knee Arthroplasty: A Markov Model

Background

Periprosthetic joint infection (PJI) is a common cause of revision total knee surgery. Although debridement and implant retention (DAIR) has lower success rates in the chronic setting, it is an accepted treatment of acute PJI, whether postoperatively or with late hematogenous seeding. There are two broad DAIR strategies: single debridement and planned double debridement. The purpose of this study is to evaluate the cost-effectiveness of single vs double DAIR for acute PJI in total knee arthroplasty.

Methods

A decision tree using single or double DAIR as the treatment strategy for acute PJI was constructed. Quality-adjusted life years and costs associated with the two treatment arms were calculated. Treatment success rates, failure rates, and mortality rates were derived from the literature. Medical costs were derived from both the literature and Medicare data. A cost-effectiveness plane was constructed from multiple Monte Carlo trials. A sensitivity analysis identified parameters most influencing the optimal strategy decision.

Results

Double DAIR was the optimal treatment strategy both in terms of the health utility state (82% of trials) and medical cost (97% of trials). Strategy tables demonstrated that as long as the success rate of double debridement is 10% or greater than the success rate of a single debridement, the two-stage protocol is cost-effective.

Conclusions

A double DAIR protocol is more cost-effective than single DAIR from a societal perspective.

Economic Evaluation of New Oral Anticoagulants in Prevention of Venous Thrombosis Following Joint Replacement Surgery: A Systematic Review

PURPOSE

The main purpose of prescribing oral anticoagulants in patients undergoing total knee and total hip replacement surgery is to prevent venous thromboembolism (VTE). The present study aimed to summarize evidence from economic evaluations regarding new oral anticoagulants (NOACs) used in VTE prophylaxis after joint replacement surgery.

METHODS

To obtain relevant literature on economic evaluations of NOACs used in the prevention of VTE following joint replacement surgery, we searched the Cochrane Library, PubMed, Web of Science, Embase, and Scopus, as well as specialized economic evaluation databases, for articles published from January 2008 to December 2019. Next, 2 reviewers screened the titles and abstracts of studies, extracted data from the full-text articles, and assessed the quality of the methodologies using the Quality of Health Economic Studies checklist.

FINDINGS

Twenty-eight studies of economic evaluations met the inclusion criteria of the research. The quality assessment showed that 20 articles had scores within the range of 75 to 100 (high quality), and 9 studies had scores within the range of 50 to 74 (moderate quality). All of the identified studies had been carried out based on modelling, and 23 studies used decision trees to model acute events after surgery. In addition, 20 studies utilized a Markov model to capture long-term complications of VTE. The results showed that rivaroxaban was more cost-effective than apixaban and dabigatran from a perspective of the health care system in the prevention of VTE after total knee and total hip replacement surgery. In addition, apixaban was associated with a lower risk for bleeding events than other NOACs, making it the most cost-effective NOAC from the perspective of the payer.

IMPLICATIONS

The results suggest that NOACs are cost-effective alternatives to low-molecular-weight heparins. Rivaroxaban and dabigatran were assessed as the most and least cost-effective prophylaxis options, respectively, after joint replacement surgery for the prevention of VTE. It is recommended that future research be conducted on economic evaluations of edoxaban.

Economic Evaluation of Rivaroxaban Versus Enoxaparin for Prevention of Venous Thromboembolism After Total Knee Replacement and Total Hip Replacement: A Systematic Review

BACKGROUND

Deep vein thrombosis (DVT) and pulmonary embolism (PE) together are called venous thromboembolism (VTE) and impose a high economic burden on healthcare systems. Thousands of people are hospitalized annually due to benign and treatable diseases but die due to PE; with the adoption of appropriate prevention, these deaths can be prevented.

OBJECTIVE

To investigate the cost-effectiveness of using rivaroxaban versus enoxaparin in published economic analyses for prevention of VTE after total knee (TKR) or hip replacement (THR).

METHOD

In a systematic review electronic searches were performed on various online databases, including PubMed, Web of science, Embase, Scopus, Health Economic Evaluations Database (HEED), and ProQuest. The inclusion criteria were: studies that were conducted on the cost-effectiveness of rivaroxaban versus enoxaparin for the prevention of VTE after TKR and THR; cost-effectiveness studies conducted using decision analysis models based on the economic evaluation approach; studies with available full-text papers; and studies written in English and published between 2007 and 2019. The exclusion criteria were: studies with partial cost effectiveness (such as effectiveness assessment, cost assessment, quality-of-life assessment); studies written in languages other than English; and all protocols, conference abstracts, and letters to the editor. The Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist was used to qualitatively evaluate the studies.

RESULTS

Of a total of 537 initial studies, nine papers met the inclusion criteria. The time scope of studies ranged from 3 months to 5 years. Among the selected studies, some studies had included discount rates (n = 4) and the other studies did not utilize discount rates and were set to zero percent by default (n = 5). In all studies, direct medical costs, including costs related to the prevention, diagnosis, and treatment of VTE and PE, and management and monitoring of treatment costs were reviewed.

CONCLUSION

The results of this systematic review showed that using rivaroxaban in patients undergoing total knee or hip replacement reduced costs and increased quality of life. However, since most of the studies had been conducted in developed countries, it is not possible to generalize the results to developing countries. Nonetheless, given that rivaroxaban is administered orally and does not require continuous monitoring, it will be less costly for patients and health systems and is more appropriate to administer it as a thromboprophylactic drug following total knee or hip replacement surgery.

Reconsidering Strategies for Managing Chronic Periprosthetic Joint Infection in Total Knee Arthroplasty: Using Decision Analytics to Find the Optimal Strategy Between One-Stage and Two-Stage Total Knee Revision

BACKGROUND

Periprosthetic joint infection (PJI) following total knee arthroplasty is a growing concern, as the demand for total knee arthroplasty (TKA) expands annually. Although 2-stage revision is considered the gold standard in management, there is substantial morbidity and mortality associated with this strategy. One-stage revision is associated with lower mortality rates and better quality of life, and there has been increased interest in utilizing the 1-stage strategy. However, surgeons are faced with a difficult decision regarding which strategy to use to treat these infections, considering uncertainty with respect to eradication of infection, quality of life, and societal costs with each strategy. The purpose of the current study was to use decision analysis to determine the optimal decision for the management of PJI following TKA.

METHODS

An expected-value decision tree was constructed to estimate the quality-adjusted life-years (QALYs) and costs associated with 1-stage and 2-stage revision. Two decision trees were created: Decision Tree 1 was constructed for all pathogens, and Decision Tree 2 was constructed solely for difficult-to-treat infections, including methicillin-resistant infections. Values for parameters in the decision model, such as mortality rate, reinfection rate, and need for additional surgeries, were derived from the literature. Medical costs were derived from Medicare data. Sensitivity analysis determined which parameters in the decision model had the most influence on the optimal strategy.

RESULTS

In both decision trees, the 1-stage strategy produced greater health utility while also being more cost-effective. In the Monte Carlo simulation for Decision Trees 1 and 2, 1-stage was the dominant strategy in about 85% and 69% of the trials, respectively. Sensitivity analysis showed that the reinfection and 1-year mortality rates were the most sensitive parameters influencing the optimal decision.

CONCLUSIONS

Despite 2-stage revision being considered the current gold standard for infection eradication in patients with PJI following TKA, the optimal decision that produced the highest quality of life was 1-stage revision. These results should be considered in shared decision-making with patients who experience PJI following TKA.

LEVEL OF EVIDENCE

Economic and Decision Analysis Level IV. See Instructions for Authors for a complete description of levels of evidence.

Cost-Utility Analysis of Venous Thromboembolism Prophylaxis Strategies for People Undergoing Elective Total Hip and Total Knee Replacement Surgeries in the English National Health Service

Background: Major orthopedic surgery, such as elective total hip replacement (eTHR) and elective total knee replacement (eTKR), are associated with a higher risk of venous thromboembolism (VTE) than other surgical procedures. Little is known, however, about the cost-effectiveness of VTE prophylaxis strategies in people undergoing these procedures. Aim: The aim of this work was to assess the cost-effectiveness of these strategies from the English National Health Service perspective to inform NICE guideline (NG89) recommendations. Materials and Methods: Cost-utility analysis, using decision modeling, was undertaken to compare 15 VTE prophylaxis strategies for eTHR and 12 for eTKR, in addition to "no prophylaxis" strategy. The analysis complied with the NICE Reference Case. Structure and assumptions were agreed with the guideline committee. Incremental net monetary benefit (INMB) was calculated, vs. the model comparator (LMWH+ antiembolism stockings), at a threshold of £20,000/quality-adjusted life-year (QALY) gained. The model was run probabilistically. Deterministic sensitivity analyses (SAs) were undertaken to assess the robustness of the results. Results: The most cost-effective strategies were LMWH for 10 days followed by aspirin for 28 days (INMB = £530 [95% CI: -£784 to £1,103], probability of being most cost-effective = 72%) for eTHR, and foot pump (INMB = £353 [95% CI: -£101 to £665]; probability of being most cost-effective = 18%) for eTKR. There was considerable uncertainty regarding the cost-effectiveness ranking in the eTKR analysis. The results were robust to change in all SAs. Conclusions: For eTHR, LMWH (standard dose) for 10 days followed by aspirin for 28 days is the most cost-effective VTE prophylaxis strategy. For eTKR, the results are highly uncertain but foot pump appeared to be the most cost-effective strategy, followed closely by aspirin (low dose). Future research should focus on assessing cost-effectiveness of VTE prophylaxis in the eTKR population.

Cost-Effectiveness Analysis of Rivaroxaban for Treatment of Deep Vein Thrombosis and Pulmonary Embolism in Greece

BACKGROUND AND OBJECTIVE

Venous thromboembolism (VTE), comprising deep-vein thrombosis (DVT) and pulmonary embolism (PE), is a major healthcare concern that results in substantial morbidity and mortality with great economic burden for healthcare systems. Hence, the need for effective and efficient treatment of patients with VTE is important for both clinical and economic reasons. The objective of this study was to evaluate the cost effectiveness of rivaroxaban compared to standard of care (SoC) with enoxaparin followed by dose-adjusted vitamin-K antagonists for the treatment of DVT and PE in Greece.

METHODS

An existing Markov model was locally adapted from a third-party payer perspective to reflect the management and complications of DVT and PE in the course of 3-month cycles, up to death. The clinical inputs and utility values were extracted from published studies. Direct medical costs, obtained from local resources, were incorporated in the model and refer to year 2017. Both costs and outcomes were discounted at 3.5%. The incremental cost-effectiveness ratio (ICER) per quality-adjusted life year (QALY) gained was calculated. Probabilistic sensitivity analysis (PSA) was carried out to deal with uncertainty.

RESULTS

The base-case analysis showed that rivaroxaban in 3- and 6-month treatment duration for DVT and PE, respectively, as this is the common clinical practice in Greece, was associated with a 0.02 and 0.01 increment in QALYs compared to SoC, respectively. Rivaroxaban was associated with a reduced total cost in DVT (€85) but with an additional total cost in PE (€2) compared to SoC. Therefore, rivaroxaban was a dominant (less costly, more effective) and cost-effective (ICER: €177) alternative over SoC for the management of DVT and PE, respectively. PSA revealed that the probability of rivaroxaban being cost effective at a threshold of €34,000 per QALY gained was 99% and 81% for DVT and PE, respectively.

CONCLUSION

Rivaroxaban may represent a cost-effective option relative to SoC for the management of DVT and PE in Greece.

Direct Oral Anticoagulants and Vitamin K Antagonists for Treatment of Deep Venous Thrombosis and Pulmonary Embolism in the Outpatient Setting: Comparative Economic Evaluation

BACKGROUND

To date, there have been few economic evaluations, from a Canadian perspective, of direct oral anticoagulants (DOACs) for the prevention of recurrent venous thromboembolism (VTE) in patients with acute unprovoked VTE. As a result, there is a lack of consensus about which treatment strategy should be adopted in the clinical setting.

OBJECTIVES

To assess the cost-effectiveness of currently approved anti-coagulant options, in terms of cost per quality-adjusted life-year (QALY) gained, for the prevention of recurrent VTE in patients with unprovoked events managed on an outpatient basis.

METHODS

Microsoft Excel was used to develop a Markov model. Model parameters were determined using published literature, local hospital data, expert opinion, and chart review. The analysis considered the costs associated with pharmaceuticals, laboratory testing, hematologist fees, and treatment of recurrent VTE and major bleeding events. Effectiveness was measured in terms of QALYs, and incremental cost-effectiveness ratios (ICERs) were calculated.

RESULTS

For treatment lasting 3 months, apixaban represented the most cost-effective DOAC relative to low-molecular-weight heparin (LMWH) + vitamin K antagonist, with an ICER of $7379.66. For 6 months of treatment, apixaban again represented the most cost-effective treatment, with an ICER of $84.08 per QALY gained, and this drug dominated all the other strategies at 12 months. For lifetime treatment, DOACs were unlikely to be cost-effective, given a maximum willingness to pay of $50 000 to $100 000 per QALY. In a probabilistic sensitivity analysis at 6 months, 46.4% of iterations resulted in apixaban having lower costs and better outcomes than LMWH + vitamin K antagonist, and 78.6% of iterations resulted in an ICER below $100 000.

CONCLUSIONS

The findings of this study suggest that apixaban is likely cost-effective for treatment durations of 3, 6, and 12 months. However, for indefinite treatment, DOACs were unlikely to be cost-effective.

Economic Evaluations of New Oral Anticoagulants for the Prevention of Venous Thromboembolism After Total Hip or Knee Replacement: A Systematic Review

BACKGROUND

Total hip replacement (THR) and total knee replacement (TKR) surgeries are being performed with increasing regularity and are associated with a high risk of developing a venous thromboembolism (VTE). New oral anticoagulants (NOACs) may be more effective at preventing VTEs but are associated with more bleeding events versus traditional anticoagulants.

OBJECTIVE

The objective of this systematic review was to identify published economic analyses of NOACs for primary VTE prophylaxis following THR and TKR surgeries, and to summarise the modelling techniques used and the cost-effectiveness results.

METHODS

Electronic searches of MEDLINE, EconLit and The Cochrane Library were performed from January 2008 to February 2015. Reference lists of included articles and reviews were examined for relevant studies.

RESULTS

Sixteen relevant economic analyses were identified, all of which used decision-tree structures to model acute events after surgery; 13 included a chronic-phase Markov module to capture long-term complications of VTE and recurrent VTE events. All studies included prophylaxis-related major bleeding events and captured both symptomatic and asymptomatic VTE-related events; nine studies distinguished between distal and proximal deep vein thrombosis events. Overall, rivaroxaban dominated enoxaparin in eight of 11 studies and dalteparin in one study, dabigatran dominated enoxaparin in five of seven studies and apixaban dominated enoxaparin in two of two studies. Rivaroxaban dominated dabigatran in four of four studies, apixaban dominated dabigatran in two of two studies and rivaroxaban dominated apixaban in one study.

CONCLUSIONS

The economic analyses showed reasonable consistency in the model structures used and the events captured. The results strongly suggested that NOACs are cost effective alternatives to low molecular-weight heparin. Dabigatran appeared to be the least cost effective NOAC. More research is needed to assess the cost effectiveness of apixaban and edoxaban.

The cost-effectiveness of surgical treatment of medial unicompartmental knee osteoarthritis in younger patients: a computer model-based evaluation

BACKGROUND

Surgical options for the management of medial compartment osteoarthritis of the varus knee include high tibial osteotomy, unicompartmental knee arthroplasty, and total knee arthroplasty. We sought to determine the cost-effectiveness of high tibial osteotomy and unicompartmental knee arthroplasty as alternatives to total knee arthroplasty for patients fifty to sixty years of age.

METHODS

We built a probabilistic state-transition computer model with health states defined by pain, postoperative complications, and subsequent surgical procedures. We estimated transition probabilities from published literature. Costs were determined from Medicare reimbursement schedules. Health outcomes were measured in quality-adjusted life-years (QALYs). We conducted analyses over patients' lifetimes from the societal perspective, with health and cost outcomes discounted by 3% annually. We used probabilistic sensitivity analyses to account for uncertainty in data inputs.

RESULTS

The estimated discounted QALYs were 14.62, 14.63, and 14.64 for high tibial osteotomy, unicompartmental knee arthroplasty, and total knee arthroplasty, respectively. Discounted total direct medical costs were $20,436 for high tibial osteotomy, $24,637 for unicompartmental knee arthroplasty, and $24,761 for total knee arthroplasty (in 2012 U.S. dollars). The incremental cost-effectiveness ratio (ICER) was $231,900 per QALY for total knee arthroplasty and $420,100 per QALY for unicompartmental knee arthroplasty. Probabilistic sensitivity analyses showed that, at a willingness-to-pay (WTP) threshold of $50,000 per QALY, high tibial osteotomy was cost-effective 57% of the time; total knee arthroplasty, 24%; and unicompartmental knee arthroplasty, 19%. At a WTP threshold of $100,000 per QALY, high tibial osteotomy was cost-effective 43% of time; total knee arthroplasty, 31%; and unicompartmental knee arthroplasty, 26%.

CONCLUSIONS

In fifty to sixty-year-old patients with medial unicompartmental knee osteoarthritis, high tibial osteotomy is an attractive option compared with unicompartmental knee arthroplasty and total knee arthroplasty. This finding supports greater utilization of high tibial osteotomy for these patients. The cost-effectiveness of high tibial osteotomy and of unicompartmental knee arthroplasty depend on rates of conversion to total knee arthroplasty and the clinical outcomes of the conversions.

Venous thromboembolism prophylaxis after total joint arthroplasty

Venous thromboembolism (VTE) prophylaxis after total joint arthroplasty is considered best practice. However, over the past 5 years, there has been considerable debate about the ideal prophylactic regimen or modality. The American Academy of Orthopaedic Surgeons and the American College of Chest Physicians published their most recent clinical practice guidelines about VTE prophylaxis in 2011 and 2012, respectively. In addition, the Surgical Care Improvement Project published their latest recommendations in 2014. In this review, commonly used VTE prophylaxis options and the latest clinical guidelines will be discussed.

Validity of standard gamble estimated quality of life in acute venous thrombosis

INTRODUCTION

The standard gamble is considered the 'gold standard' technique for measuring quality of life. We recently used the standard gamble to estimate quality of life in acute venous thrombosis, and found unexpected variability in the responses. The current study aimed to explore the reasons for variability by comparing the standard gamble technique in patients with acute venous thrombosis to other quality of life measurement tools.

MATERIALS AND METHODS

Thrombosis clinic patients treated for venous thrombosis were eligible to participate. Patients evaluated their current health state by performing a standard gamble interview, reporting on a visual analogue scale, completing the SF-36 and disease specific questionnaires (PEmb-Qol and VEINES-QOL/Sym). Validity was assessed by correlating the standard gamble utilities with the other methods. Test-retest reliability, responsiveness and acceptability were also assessed.

RESULTS

Forty-four patients were interviewed, with 16 attending for a repeat interview. The median standard gamble utility was 0.97 (0.84-1.0), SF-6D 0.64 (0.59 - 0.80) and visual analogue score 70 (60 - 80). Participants with pulmonary embolism had lower standard gamble estimates than those with deep vein thrombosis. There was good discriminant validity in that the standard gamble estimates were not associated with risk taking behavior, negative outlook, sex or education. Test-retest reliability with the standard gamble was moderate and there was evidence of a ceiling effect.

CONCLUSIONS

Standard gamble utilities are higher than other methods of measuring quality of life in venous thrombosis. The choice of utility values adopted in studies will impact on future economic studies.

Cost-effectiveness of rivaroxaban versus warfarin anticoagulation for the prevention of recurrent venous thromboembolism: a U.S. perspective

INTRODUCTION

Rivaroxaban is an oral direct factor Xa inhibitor that is noninferior to warfarin in the prevention of recurrent venous thromboembolism (VTE). Whether rivaroxaban is cost-effective in the prevention of recurrent VTE, however, is not known.

MATERIAL AND METHODS

To assess the cost effectiveness of rivaroxaban compared with warfarin in the prevention of recurrent VTE, we built a Markov state-transition model over a 10-year time horizon. The base case analysis consisted of a hypothetical cohort of 60-year-old patients with an initial VTE who received secondary prophylaxis with either rivaroxaban or warfarin for 3 to 12months. Cost estimates were derived from the Healthcare and Utilization Project and other sources. Probabilities were based on literature values. Outcomes included costs in 2011 United States dollars, quality-adjusted life-years (QALYs), and incremental cost effectiveness ratios (ICERs) over 10years from a societal perspective.

RESULTS

Compared with warfarin, the rivaroxaban strategy cost less ($3,195 vs. $6,188) and was more effective (9.29 QALYs vs 9.14 QALYs). Our results were highly robust in sensitivity analyses. Warfarin was no longer dominated by rivaroxaban when the risk of major bleeding with rivaroxaban exceeds 3.8% (base case estimate: 0.96%).

CONCLUSION

In summary, prophylactic anticoagulation with rivaroxaban appears to be a cost effective, and perhaps cost saving, alternative to warfarin for the prevention of recurrent VTE.

Venous thromboembolism: annualised United States models for total, hospital-acquired and preventable costs utilising long-term attack rates

Healthcare reform is upon the United States (US) healthcare system. Prioritisation of preventative efforts will guide necessary transitions within the US healthcare system. While annual deep-vein thrombosis (DVT) costs have recently been defined at the US national level, annual pulmonary embolism (PE) and venous thromboembolism (VTE) costs have not yet been defined. A decision tree and cost model were developed to estimate US health care costs for total PE, total hospital-acquired PE, and total hospital-acquired "preventable" PE. The previously published DVT cost model was modified, updated and combined with the PE cost model to elucidate the same three categories of costs for VTE. Direct and indirect costs were also delineated. For VTE in the base model, annual cost ranges in 2011 US dollars for total, hospital- acquired, and hospital-acquired "preventable" costs and were $13.5-$27.2, $9.0-$18.2, and $4.5-$14.2 billion, respectively. The first sensitivity analysis, with higher incidence rates and costs, demonstrated annual US total, hospital-acquired, and hospital-acquired "preventable" VTE costs ranging from $32.1-$69.3, $23.7-$51.5, and $11.9-$39.3 billion, respectively. The second sensitivity analysis with long-term attack rates (LTAR) for recurrent events and post-thrombotic syndrome and chronic pulmonary thromboembolic hypertension demonstrated annual US total, hospital-acquired, and hospital-acquired "preventable" VTE costs ranging from $15.4-$34.4, $10.3-$25.4, and $5.1-$19.1 billion, respectively. PE costs comprised a majority of the VTE costs. Prioritisation of effective VTE preventative strategies will reduce significant costs, morbidity and mortality within the US healthcare system. The cost models may be utilised to estimate other countries' costs or VTE-specific disease states.