Cost-of-Illness Analysis of Long-Term Health Care Resource Use and Disease Burden in Patients With Pulmonary Embolism: Insights From the PREFER in VTE Registry

Background As mortality from pulmonary embolism (PE) decreases, the personal and societal costs among survivors are receiving increasing attention. Detailing this burden would support an efficient public health resource allocation. We aimed to provide estimates for the economic and disease burden of PE also accounting for long-term health care use and both direct and indirect costs beyond the acute phase. Methods and Results This is a cost-of-illness analysis with a bottom-up approach based on data from the PREFER in VTE registry (Prevention of Thromboembolic Events-European Registry in Venous Thromboembolism). We calculated direct (clinical events and anticoagulation) and indirect costs (loss of productivity) of an acute PE event and its 12-month follow-up in 2020 Euros. We estimated a disability weight for the 12-month post-PE status and corresponding disability adjusted life years presumably owing to PE. Disease-specific costs in the first year of follow-up after an incident PE case ranged between 9135 Euros and 10 620 Euros. The proportion of indirect costs was 42% to 49% of total costs. Costs were lowest in patients with ongoing cancer, mainly because productivity loss was less evident in this already burdened population. The calculated disability weight for survivors who were cancer free 12 months post-PE was 0.017, and the estimated disability adjusted life years per incident case were 1.17. Conclusions The economic burden imposed by PE to society and affected patients is considerable, and productivity loss is its main driver. The disease burden from PE is remarkable and translates to the loss of roughly 1.2 years of healthy life per incident PE case.

Cost-of-illness analysis of long-term healthcare resource utilization and disease burden in patients with pulmonary embolism: insights from the PREFER in VTE registry

Background

Pulmonary embolism (PE) is responsible for considerable personal and societal costs. Detailing this burden would support an efficient public health resource allocation. However, cost estimates so far have failed to account for both resource utilization and excess costs in its long-term management beyond the acute phase.

Purpose

To provide estimates for the economic and disease burden of PE in the European Union (EU) also accounting for long-term healthcare utilization and costs beyond the acute phase.

Methods

This is a cost-of-illness analysis, from a societal perspective, with a bottom-top approach and a time horizon of 12 months based on data from the PREFER in VTE registry. We calculated direct and indirect costs of an acute PE event and its 12-month follow-up. We used cost inputs derived from the literature and as directly reported in the PREFER in VTE registry and we adjusted them for inflation and purchasing power parity to 2020 Euros (€). Total average costs per PE patient comprised six general categories: costs for the index PE hospitalization; costs for clinical events during follow-up; costs for anticoagulation after the index event; costs for ambulatory visits during follow-up; the patient's own contribution; and costs related to productivity loss (using the friction cost method). A stratified analysis was performed according to the presence of active cancer, non-cancer provoked PE, and unprovoked PE. In addition, we used the EQ-5D health questionnaire to derive a disability weight for the post-PE state 12 months after the index event and the corresponding disability adjusted life years (DALYs) presumably due to PE.

Results

Annual disease-specific costs for each incident PE case ranged between 9,135 € and 10,620 €. Costs for patients with cancer (8,274 to 9,752 €) and patients with unprovoked PE (8,695 to 9,612 €) were lower than costs for non-cancer patients with provoked PE (10,423 to 11,307 €), mainly due to differences in productivity loss. The indirect costs were mainly driven by productivity losses and their proportion to total costs was 42–49% for the overall population (28–33% for cancer, 52–56% for non-cancer provoked PE and 43–47% for unprovoked PE) (Figure 1). Anticoagulation accounted for 18–21% of total costs for cancer patients (while only 5–6% for non-cancer patients) and was primarily driven by the use of low-molecular-weight heparins and fondaparinux (Figure 2). The calculated disability weight for cancer-free survivors of PE 12 months after the index event was 0.017 (bootstrapped 95% CI 0.0002–0.0344) and the estimated annual DALYs per incident case were 1.17 (bootstrapped 95% CI 0.75–1.59).

Conclusion

PE imposes a significant annual economic burden, for which productivity loss is the main driver. Total costs in the EU could range between 0.5 and 3.8 billion €. The disease burden from PE is notable and translates to the loss of roughly 1.2 years of healthy life per incident PE case per year.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): This study was supported by an unrestricted grant from Daiichi Sankyo (Title: “Filling the gaps of knowledge on healthcare outcomes during long-term anticoagulant treatment of pulmonary embolism”, grant number DSE-DE-CV-20001).

Potential Drug Interactions between Recombinant Interleukin-2 and Direct Oral Anticoagulants: Indirect Evidence from In Vivo Animal Studies

Recombinant interleukin-2 (rIL-2) is indicated for metastatic renal cell carcinoma and melanoma. Over recent years low-dose rIL-2 has been studied for the treatment of autoimmune diseases and acute coronary syndrome because of its ability to expand and activate T regulatory (T_reg) cells. However, several medical conditions potentially benefiting from rIL-2 administrations are characterized by an intrinsic prothrombotic risk, thus requiring concurrent anticoagulation. In our systematic review of the literature, we investigated the potential for drug interactions between oral anticoagulants and rIL-2 by assessing the influence of rIL-2 administration on transporters and cytochromes determining the pharmacokinetics of (direct) oral anticoagulants. We extracted data from 12 studies, consisting of 11 animal studies and one study in humans. Eight studies investigated the pharmacokinetics of P-glycoprotein (P-gp) substrates and reported that the intraperitoneal rIL-2 administration may inhibit intestinal P-gp. Four studies on hepatic cytochrome P450 yielded conflicting results. The only human study included in this systematic review concluded that rIL-2 suppresses the hepatic cytochrome P450, but only if given at higher doses. Based on the results from animal studies, the co-administration of rIL-2 and dabigatran etexilate, a substrate of intestinal P-gp, may lead to higher dabigatran plasma concentrations and bioavailability. Human studies should confirm whether this potential interaction is clinically relevant.

Anticoagulant Reversal Strategies in the Emergency Department Setting: Recommendations of a Multidisciplinary Expert Panel

Bleeding is the most common complication of anticoagulant use. The evaluation and management of the bleeding patient is a core competency of emergency medicine. As the prevalence of patients receiving anticoagulant agents and variety of anticoagulants with different mechanisms of action, pharmacokinetics, indications, and corresponding reversal agents increase, physicians and other clinicians working in the emergency department require a current and nuanced understanding of how best to assess, treat, and reverse anticoagulated patients. In this project, we convened an expert panel to create a consensus decision tree and framework for assessment of the bleeding patient receiving an anticoagulant, as well as use of anticoagulant reversal or coagulation factor replacement, and to address controversies and gaps relevant to this topic. To support decision tree interpretation, the panel also reached agreement on key definitions of life-threatening bleeding, bleeding at a critical site, and emergency surgery or urgent invasive procedure. To reach consensus recommendations, we used a structured literature review and a modified Delphi technique by an expert panel of academic and community physicians with training in emergency medicine, cardiology, hematology, internal medicine/thrombology, pharmacology, toxicology, transfusion medicine and hemostasis, neurology, and surgery, and by other key stakeholder groups.

Postthrombotic Syndrome in Patients Treated With Rivaroxaban or Warfarin for Venous Thromboembolism

Postthrombotic syndrome (PTS) is a frequent complication of venous thromboembolism (VTE). Using MarketScan claims data from January 2012 to June 2015, we identified adults with a primary diagnosis code for VTE during a hospitalization/emergency department visit, ≥6 months of insurance coverage prior to the index event and newly started on rivaroxaban or warfarin within 30 days of the index VTE. Patients with <4-month follow-up postindex event or a claim for any anticoagulant during 6-month baseline period were excluded. Differences in baseline characteristics between rivaroxaban and warfarin users were adjusted for using inverse probability of treatment weights based on propensity scores. Patients were followed for the development of PTS starting 3 months after the index VTE. Cox regression was performed and reported as hazard ratios with 95% confidence intervals (CIs). In total, 10 463 rivaroxaban and 26 494 warfarin users were followed for a mean of 16 ± 9 (range, 4-39) months. Duration of anticoagulation was similar between cohorts (median = 6 months). Rivaroxaban was associated with a 23% (95% CI: 16-30) reduced hazard of PTS versus warfarin. Rivaroxaban was associated with a significant risk reduction in symptoms of PTS compared to warfarin in patients with VTE treated in routine practice.

Venous thromboembolism: role of pharmacists and managed care considerations

Venous thromboembolism (VTE) includes deep vein thrombosis and pulmonary embolism. Anticoagulation is used in patients with VTE to reduce the risk of recurrent VTE and VTE-related death. The overall incidence of VTE is 1 to 2 per 1000 person-years. Long-term mortality for patients with VTE is poor, with 25% of patients not surviving 7 days and nearly 40% not surviving the first year. Coagulation disorders demand effective anticoagulant therapy to avoid complications, especially recurrent VTE and VTE-related death. For more than 60 years, warfarin has been the cornerstone of therapy for patients requiring anticoagulation and was the sole oral anticoagulant available in the United States until 2010. Since then, the FDA has approved 5 direct-acting oral anticoagulants (DOACs) that inhibit single coagulation factors (factor Xa and thrombin). DOACs provide predictable anticoagulation with fixed dosing, easier perioperative management, no routine laboratory monitoring, and fewer food-drug interactions. However, when choosing DOACs, clinicians must consider several issues in addition to efficacy and safety before employing these therapies, including patient-specific factors, adherence and persistence with therapy, and their cost-effectiveness for clinical use.

European Union-28: An annualised cost-of-illness model for venous thromboembolism

Annual costs for venous thromboembolism (VTE) have been defined within the United States (US) demonstrating a large opportunity for cost savings. Costs for the European Union-28 (EU-28) have never been defined. A literature search was conducted to evaluate EU-28 cost sources. Median costs were defined for each cost input and costs were inflated to 2014 Euros (€) in the study country and adjusted for Purchasing Power Parity between EU countries. Adjusted costs were used to populate previously published cost-models based on adult incidence-based events. In the base model, annual expenditures for total, hospital-associated, preventable, and indirect costs were €1.5–2.2 billion, €1.0–1.5 billion, €0.5–1.1 billion and €0.2–0.3 billion, respectively (indirect costs: 12 % of expenditures). In the long-term attack rate model, total, hospital-associated, preventable, and indirect costs were €1.8–3.3 billion, €1.2–2.4 billion, €0.6–1.8 billion and €0.2–0.7 billion (indirect costs: 13 % of expenditures). In the multiway sensitivity analysis, annual expenditures for total, hospital-associated, preventable, and indirect costs were €3.0–8.5 billion, €2.2–6.2 billion, €1.1–4.6 billion and €0.5–1.4 billion (indirect costs: 22 % of expenditures). When the value of a premature life-lost increased slightly, aggregate costs rose considerably since these costs are higher than the direct medical costs. When evaluating the models aggregately for costs, the results suggests total, hospital-associated, preventable, and indirect costs ranging from €1.5–13.2 billion, €1.0–9.7 billion, €0.5–7.3 billion and €0.2–6.1 billion, respectively. Our study demonstrates that VTE costs have a large financial impact upon the EU-28’s healthcare systems and that significant savings could be realised if better preventive measures are applied.

Extended thromboprophylaxis in the acutely ill medical patient after hospitalization - a paradigm shift in post-discharge thromboprophylaxis

Venous thromboembolism (VTE) is a significant healthcare burden with approximately 900,000 events annually in the United States, over half of which are healthcare-associated. This number is anticipated to double by 2050. Group prophylaxis strategies confined to the inpatient setting appear to have minimal impact on the reduction of post-discharge VTE in medically ill patients due to shortened lengths of stay and a heterogenous population that includes patients at low risk for VTE. In accordance with current guideline recommendations, very few (<5%) medically ill patients are discharged with extended prophylaxis, which potentially creates a clinical gap for at-risk patients as VTE risk has been shown to persist for up to 90 days. Initial studies of extended thromboprophylaxis in acutely ill medical patients with enoxaparin, rivaroxaban and apixaban showed little to no benefit towards VTE reduction that was consistently outweighed by increased bleeding. The more recent APEX study that compared betrixaban to enoxaparin in an enriched patient population at high-risk for VTE was the first study of extended thromboprophylaxis that showed similar efficacy in VTE prevention without an increase in major bleeding. Based on the APEX results, betrixaban recently gained FDA approval for extended thromboprophylaxis in acutely ill medical patients. Recognition that up to half of medically ill patients are not at sufficient risk to warrant thromboprophylaxis has driven extensive research towards development of scientifically derived and validated VTE risk assessment models intended to identify patients who do not warrant prophylaxis, as well as those at high risk who may derive benefit from extended thromboprophylaxis. This article will review prior and ongoing extended thromboprophylaxis studies, VTE and bleed risk assessment models, incorporation of biomarkers in VTE risk assessment and key issues in the paradigm shift towards individualized VTE prophylaxis in acutely ill medical patients.

Renal Function and Direct Oral Anticoagulant Treatment for Venous Thromboembolism

Because differences in renal function can affect the efficacy and safety of direct oral anticoagulants, prescribing an appropriate dose based on renal function is critical, especially in patient populations with a high incidence of renal impairment. In patients with nonvalvular atrial fibrillation and mild or moderate renal impairment, direct oral anticoagulants are associated with a better risk-benefit profile compared with warfarin. However, less is known regarding outcomes in patients with venous thromboembolism and renal impairment. The efficacy and safety of direct oral anticoagulants in patients with venous thromboembolism and renal impairment are primarily derived from prespecified subgroup analyses of the phase 3 clinical trials. We summarize the available data on direct oral anticoagulant use in patients with venous thromboembolism and renal impairment. Clinicians are encouraged to follow study inclusion/exclusion criteria and perform renal dose adjustments based on the Cockcroft-Gault equation using actual body weight when indicated to avoid adverse events.

Reversing factor Xa inhibitors - clinical utility of andexanet alfa

Approximately half of patients started on an oral anticoagulant in the USA now receive one of the newer direct oral anticoagulants (DOACs). Although there is an approved reversal agent for the direct thrombin inhibitor dabigatran, a specific reversal agent for the anti-factor Xa (FXa) DOACs has yet to be licensed. Unlike the strategy to reverse the only oral direct thrombin inhibitor with idarucizumab, which is a humanized monoclonal antibody fragment, a different approach is necessary to design a single agent that can reverse multiple anti-FXa medications. Andexanet alfa is a FXa decoy designed to reverse all anticoagulants that act through this part of the coagulation cascade including anti-FXa DOACs, such as apixaban, edoxaban and rivaroxaban, and indirect FXa inhibitors such as low-molecular-weight heparins. This narrative reviews the development of andexanet alfa and explores its basic science, pharmacokinetics/pharmacodynamics, animal models, and human studies.

Guidance for the practical management of the direct oral anticoagulants (DOACs) in VTE treatment

Venous thromboembolism (VTE) is a serious medical condition associated with significant morbidity and mortality, and an incidence that is expected to double in the next forty years. The advent of direct oral anticoagulants (DOACs) has catalyzed significant changes in the therapeutic landscape of VTE treatment. As such, it is imperative that clinicians become familiar with and appropriately implement new treatment paradigms. This manuscript, initiated by the Anticoagulation Forum, provides clinical guidance for VTE treatment with the DOACs. When possible, guidance statements are supported by existing published evidence and guidelines. In instances where evidence or guidelines are lacking, guidance statements represent the consensus opinion of all authors of this manuscript and are endorsed by the Board of Directors of the Anticoagulation Forum.

The authors of this manuscript first developed a list of pivotal practical questions related to real-world clinical scenarios involving the use of DOACs for VTE treatment. We then performed a PubMed search for topics and key words including, but not limited to, apixaban, antidote, bridging, cancer, care transitions, dabigatran, direct oral anticoagulant, deep vein thrombosis, edoxaban, interactions, measurement, perioperative, pregnancy, pulmonary embolism, reversal, rivaroxaban, switching, \thrombophilia, venous thromboembolism, and warfarin to answer these questions. Non- English publications and publications > 10 years old were excluded. In an effort to provide practical information about the use of DOACs for VTE treatment, answers to each question are provided in the form of guidance statements, with the intent of high utility and applicability for frontline clinicians across a multitude of care settings.

Practical aspects of treatment with target specific anticoagulants: initiation, payment and current market, transitions, and venous thromboembolism treatment

Target specific anticoagulants (TSOACs) have recently been introduced to the US market for multiple indications including venous thromboembolism (VTE) prevention in total hip and knee replacement surgeries, VTE treatment and reduction in the risk of stroke in patients with non-valvular atrial fibrillation (NVAF). Currently, three TSOACs are available including rivaroxaban, apixaban, and dabigatran with edoxaban currently under Food and Drug Administration review for VTE treatment and stroke prevention in NVAF. The introduction of these agents has created a paradigm shift in anticoagulation by considerably simplifying treatment and anticoagulant initiation for patients by giving clinicians the opportunity to use a rapid onset, rapid offset, oral agent. The availability of these rapid onset TSOACs is allowing for outpatient treatment of low risk pulmonary embolism and deep vein thrombosis which can greatly reduce healthcare costs by avoiding inpatient hospitalizations and treatment for the disease. Additionally with this practice, the complications of an inpatient hospitalization may also be avoided such as nosocomial infections. Single-agent approaches with TSOACs represent a paradigm shift in the treatment of VTE versus the complicated overlap of a parenteral agent with warfarin. Transitions between anticoagulants, including TSOACs, are a high-risk period for the patient, and clinicians must carefully consider patient characteristics such as renal function as well as the agents that are being transitioned. TSOAC use appears to be growing slowly with improved payment coverage throughout the US.

External validation of a risk assessment model for venous thromboembolism in the hospitalised acutely-ill medical patient (VTE-VALOURR)

Venous thromboembolic (VTE) risk assessment remains an important issue in hospitalised, acutely-ill medical patients, and several VTE risk assessment models (RAM) have been proposed. The purpose of this large retrospective cohort study was to externally validate the IMPROVE RAM using a large database of three acute care hospitals. We studied 41,486 hospitalisations (28,744 unique patients) with 1,240 VTE hospitalisations (1,135 unique patients) in the VTE cohort and 40,246 VTE-free hospitalisations (27,609 unique patients) in the control cohort. After chart review, 139 unique VTE patients were identified and 278 randomly-selected matched patients in the control cohort. Seven independent VTE risk factors as part of the RAM in the derivation cohort were identified. In the validation cohort, the incidence of VTE was 0.20%; 95% confidence interval (CI) 0.18-0.22, 1.04%; 95%CI 0.88-1.25, and 4.15%; 95%CI 2.79-8.12 in the low, moderate, and high VTE risk groups, respectively, which compared to rates of 0.45%, 1.3%, and 4.74% in the three risk categories of the derivation cohort. For the derivation and validation cohorts, the total percentage of patients in low, moderate and high VTE risk occurred in 68.6% vs 63.3%, 24.8% vs 31.1%, and 6.5% vs 5.5%, respectively. Overall, the area under the receiver-operator characteristics curve for the validation cohort was 0.7731. In conclusion, the IMPROVE RAM can accurately identify medical patients at low, moderate, and high VTE risk. This will tailor future thromboprophylactic strategies in this population as well as identify particularly high VTE risk patients in whom multimodal or more intensive prophylaxis may be beneficial.

Antithrombotic medication use and bleeding risk in medically ill patients after hospitalization

BACKGROUND

Hospitalized medically ill patients receiving antithrombotic medications experience increased risk of bleeding. We examined antithrombotic use, bleeding rates, and associated risk factors at 30 days post discharge.

METHODS

This retrospective database analysis included nonsurgical patients aged ≥40 years hospitalized for ≥2 days during 2005 to 2009. Previously cited, validated International Classification of Diseases, Ninth Revision, Clinical Modification codes for major bleeding were used to define clinically relevant bleeding.

RESULTS

Of the 327,578 patients, 9.1% received antithrombotic medications, of which 3.7% were anticoagulants. Rates of major and minor bleeding were 1.8% and 7.1%, respectively. Preindex gastroduodenal ulcer, thromboembolic stroke, blood dyscrasias, liver disease, and rehospitalization were the strongest predictors of major bleeding. Other risk factors included increasing age, male gender, and hospital stay of ≥3 days.

CONCLUSIONS

Careful consideration of these demonstrated bleed-associated comorbidities before initiating anticoagulation or combining antithrombotic medications in medically ill patients may improve strategies for prevention of postdischarge thromboembolism.

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.

Venous thromboembolism pharmacy intervention management program with an active, multifaceted approach reduces preventable venous thromboembolism and increases appropriate prophylaxis

Two concepts relating to venous thromboembolism (VTE) prevention have recently emerged-"appropriate" prophylaxis and "preventable" VTE. We evaluated whether a human alert, as part of a pharmacy intervention program, can increase appropriate prophylaxis and decrease preventable symptomatic VTE in hospitalized patients. This prospective study with retrospective data collection was conducted utilizing data from 1879 patients in 2006 as a control cohort. The intervention cohort data were from 1646 patients during 2007, after program implementation. The rate of appropriate prophylaxis increased from 23.8% in 2006 to 37.9% in 2007 (odds ratio 1.8; 95% confidence interval [CI] = 1.6-2.1; P < .0001). Preventable VTE incidence was reduced by 74% (95% CI = 44%-88%) from 18.6 to 4.9 per 1000 patient discharges in 2006 and 2007, respectively (P = .0006). In conclusion, a pharmacy-led multifaceted intervention can significantly increase the rates of appropriate prophylaxis and significantly reduce the incidence of preventable VTE in hospitalized patients.

Venous thromboembolism prevention: a systematic review of methods to improve prophylaxis and decrease events in the hospitalized patient

Prevention of venous thromboembolism (VTE) is currently a key initiative internationally and in US hospitals, where there has been a recent focus on national quality initiatives to prevent hospital-acquired VTE. Multiple strategies exist to prevent VTE by increasing prophylaxis rates in the hospitalized setting. Active, multifaceted interventions, including provider education, an active reminder to the provider, and regular audit and feedback to medical and hospital staff, appear to be the most effective current interventions. Active intervention programs have been validated both as electronic alerts, with or without computerized clinical decision support software and, more recently, human alerts, many of which utilize in-hospital pharmacists. A passive strategy, such as guideline dissemination, should not be used as a lone method. Although inappropriate duration remains a key reason as to why at-risk patients do not receive appropriate thromboprophylaxis within the hospital (defined by type, dose, and duration of prophylaxis), few studies address duration compared with hospital length of stay. Preventable VTE is a new quality outcome measure for hospitals but is measured in few studies. Future studies should focus on comparing various multifaceted interventions to assess their effect over time, including endpoints of bleeding for safety, appropriate type, dose, and duration of prophylaxis, overall and preventable VTE, and the impact on unnecessary prophylaxis for patients not at risk.

Venous thromboembolism prophylaxis with unfractionated heparin in the hospitalized medical patient: the case for thrice daily over twice daily dosing

For venous thromboembolism (VTE) prevention in the hospitalized medical patient, no head-to-head trials have been performed of unfractionated heparin (UFH) 5,000 U subcutaneously thrice (i.e. q8 h or TID) daily versus twice daily (q12 h or BID). Several meta-analyses have been undertaken in attempts to determine whether one regimen may be more beneficial for safety and efficacy. Currently, not all international guidelines include a recommended frequency for UFH. Delineation of this frequency may be helpful to the practicing clinician. Primary studies (with a modified Jadad score of >or=6 to demonstrate a stronger study design) that compared low molecular weight heparin (LMWH) and UFH, and UFH and placebo were evaluated. Meta-analyses evaluating safety and efficacy of LMWH versus UFH, or TID UFH versus BID UFH were also evaluated. Although BID UFH shows some efficacy in one primary study, it is no more beneficial than no prophylaxis in another study. LMWH appears to be more efficacious than BID UFH, but comparable in safety and efficacy to TID UFH. Meta-analytic data demonstrates that BID UFH may have some reduction in deep vein thrombosis. Meta-analytic data also suggests that TID UFH is more efficacious than BID UFH at the cost of more major bleeding. The medical patient with risk factors for the development of VTE appears to be at moderate to high risk. International guidelines for VTE prevention should incorporate a frequency for UFH to guide use. TID UFH is superior in efficacy to BID UFH even when taking into consideration the increased rate of major bleeds. Newly published risk-assessment models may be beneficial in determining which patients would best benefit from BID UFH or TID UFH.