Low-molecular-weight heparin in pediatric patients with thrombotic disease: a dose finding study

OBJECTIVE

To compare low-molecular-weight preparations of heparin (LMWH) with standard heparin in children requiring anticoagulant treatment for thromboembolic disease.

METHODS

We treated 25 children who required heparin, but were at significant risk of bleeding, with LMWH (enoxaparin, Rhone-Poulenc Rorer). The median age was 4 years (range, newborn to 17 years), with nine infants less than 2 months of age. Fourteen children had a deep vein thrombosis or pulmonary embolism, nine had thrombotic complications in the central nervous system, and two had complex congenital heart disease, for which they received prophylaxis at a lower dosage (0.5 mg/kg given subcutaneously twice a day). The remaining 23 children received an initial dose of 1 mg/kg, every 12 hours subcutaneously, with subsequent doses adjusted to achieve a 4-hour anti-factor Xa level between 0.5 and 1.0 unit/ml.

RESULTS

Newborn infants had increased dose requirements; an average of 1.60 units/kg was required to achieve therapeutic heparin levels. For the remaining children, the initial dose of 1.0 mg/kg was sufficient. After the initial dose adjustment, LMWH was administered with twice-weekly monitoring. The median duration of therapy with LMWH was 14 days. Two children with previously documented gastrointestinal ulcers bled and required transfusion therapy. Therapy with LMWH was continued without further events. There were no new thrombotic events during the treatment with LMWH. The cost of administering LMWH compared with heparin was reduced by 30% because of decreased laboratory monitoring, blood sampling times, intravenous starts, and nursing time. Needle punctures were reduced with LMWH therapy by the placement of a subcutaneous catheter.

CONCLUSION

These results provide the basis for a randomized, controlled trial comparing LMWH with standard heparin in pediatric patients.

Management of acute proximal deep vein thrombosis: pharmacoeconomic evaluation of outpatient treatment with enoxaparin vs inpatient treatment with unfractionated heparin

OBJECTIVES

A landmark Canadian randomized controlled clinical trial compared treatment of acute proximal vein thrombosis via low-molecular-weight heparin (LMWH) [enoxaparin] administered primarily at home with IV unfractionated heparin (UH) in the hospital. Results demonstrated equivalent safety and efficacy for home care with enoxaparin with a reduction in cost. Our objective was to validate these findings in the routine practice setting of a US health maintenance organization.

DESIGN

Retrospective analysis of medical and administrative records of health-plan members meeting inclusion-exclusion criteria of the Canadian trial during the period from 1995 to 1998.

SETTING

Staff-model health maintenance organization serving New Mexico.

PATIENTS

Persons presenting as outpatients from 1995 to 1996 or from 1997 to 1998 with acute, proximal deep vein thrombosis (DVT) diagnosed by duplex ultrasonography.

INTERVENTIONS

Initial anticoagulant therapy of IV UH administered in the hospital (from 1995 to 1996 group, n = 64) or subcutaneous LMWH (enoxaparin) administered primarily at home (from 1997 to 1998 group, n = 65), followed by warfarin therapy.

RESULTS

No statistically significant differences were observed in the number of recurrent venous thromboembolic events (p = 0.36) or bleeding events (p = 1.0). Mean +/- SD cost per patient was 9,347 dollars +/- 8,469 in the enoxaparin group compared with 11,930 dollars +/- 10,892 in the UH group, a difference of - 2,583 dollars (95% bootstrap-adjusted asymmetrical confidence interval, - 6,147 dollars, + 650 dollars).

CONCLUSIONS

Retrospective replication of the Canadian study in a US routine (managed) care setting found similar clinical and economic outcomes. Treatment of acute proximal DVT with enoxaparin in a primarily outpatient setting can be accomplished safely and yields savings through avoidance or minimization of inpatient stays.

Enoxaparin vs. unfractionated heparin for anticoagulation during continuous veno-venous hemofiltration: a randomized controlled crossover study

OBJECTIVE

The purpose of this study was to evaluate the efficacy and safety of the low molecular weight heparin enoxaparin as anticoagulant in continuous veno-venous hemofiltration (CVVH) compared with unfractionated heparin.

DESIGN

Prospective randomized controlled crossover study.

SETTING

Medical and Surgical Intensive Care Unit of a University Hospital.

PATIENTS

Forty consecutive adult medical and surgical ICU patients with normal anticoagulation parameters requiring CVVH.

INTERVENTION

CVVH was performed with pre-filter fluid replacement at 2500 ml/h and blood flow rates of 180 ml/min. Heparin-treated patients received an initial pre-filter bolus of 30 IU/kg and a maintenance infusion at 7 units/kg h(-1), titrated to achieve a systemic activated partial thromboplastin time (aPTT) of 40-45 s. Enoxaparin-treated patients received an initial pre-filter bolus of 0.15 mg/kg and a maintenance infusion starting at 0.05 mg/kg h(-1), which was subsequently adjusted to maintain systemic anti-factor Xa activity (anti-Xa) at 0.25-0.30 IU/ml. Each patient received both regimens in a crossover design. Maximum treatment duration for each set was 72 h.

RESULTS

Patients included had a mean APACHE II score of 22 (10-35). Thirty-seven patients completed both study arms. Mean filter life span was 21.7 h (+/- 16.9 h) for heparin and 30.6 h (+/- 25.3) for enoxaparin (p = 0.017, ANOVA for repeated measures). One major bleeding episode occurred during heparin as well as during enoxaparin treatment. Cost analysis showed average daily costs of 270 and 240 euro for heparin and enoxaparin, respectively.

CONCLUSION

Enoxaparin can be safely used for anticoagulation during CVVH resulting in higher filter lifespan compared with unfractionated heparin.

The cost-effectiveness of fondaparinux compared with enoxaparin as prophylaxis against thromboembolism following major orthopedic surgery

BACKGROUND

The selective antithrombotic fondaparinux is more effective than the low-molecular-weight heparin enoxaparin for prevention of venous thromboembolism (deep-vein thrombosis [DVT] or pulmonary embolism) in patients undergoing major orthopedic surgery, but its cost-effectiveness is undetermined.

OBJECTIVES

To evaluate the cost-effectiveness of fondaparinux relative to enoxaparin as prophylaxis against venous thromboembolism (VTE) for patients undergoing total hip replacement, total knee replacement or hip fracture surgery in the UK.

PATIENTS/METHODS

A decision analysis model was created simulating the impact of fondaparinux and enoxaparin on patient outcomes and costs over various time points up to 5 years following surgery. The main outcome measures were treatment costs per patient and the incidence of clinical VTE and VTE-related deaths. A weighted (combined) cohort reflects the proportion of patients undergoing these procedures in 2000/2001.

RESULTS

In the combined cohort, compared with enoxaparin, fondaparinux is expected to produce 20 fewer clinical VTE events and 3.2 fewer VTE-related deaths per 1000 procedures at 5 years. Cost savings at 5 years are pound 27 per patient with fondaparinux (discounted at 6% per year). In each of the three surgical groups, fondaparinux leads to lower expected costs per patient and to a smaller number of VTE events and VTE-related deaths. RESULTS are sensitive to the price difference between fondaparinux and enoxaparin and variation in the rate of late DVT. The analysis is robust to variations in all other key parameters.

CONCLUSIONS

Compared with enoxaparin, fondaparinux is more effective and reduces costs to the healthcare system. At current prices, fondaparinux is the recommended strategy in the UK for prophylaxis following major orthopedic surgery.

Cost-effectiveness of rivaroxaban compared with enoxaparin plus a vitamin K antagonist for the treatment of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE), comprised of deep vein thrombosis (DVT) and pulmonary embolism (PE), is commonly treated with a low-molecular-weight heparin such as enoxaparin plus a vitamin K antagonist (VKA) to prevent recurrence. Administration of enoxaparin + VKA is hampered by complexities of laboratory monitoring and frequent dose adjustments. Rivaroxaban, an orally administered anticoagulant, has been compared with enoxaparin + VKA in the EINSTEIN trials. The objective was to evaluate the cost-effectiveness of rivaroxaban compared with enoxaparin + VKA as anticoagulation treatment for acute, symptomatic, objectively-confirmed DVT or PE.

METHODS

A Markov model was built to evaluate the costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios associated with rivaroxaban compared to enoxaparin + VKA in adult patients treated for acute DVT or PE. All patients entered the model in the 'on-treatment' state upon commencement of oral rivaroxaban or enoxaparin + VKA for 3, 6, or 12 months. Transition probabilities were obtained from the EINSTEIN trials during treatment and published literature after treatment. A 3-month cycle length, US payer perspective ($2012), 5-year time horizon and a 3% annual discount rate were used.

RESULTS

Treatment with rivaroxaban cost $2,448 per-patient less and was associated with 0.0058 more QALYs compared with enoxaparin + VKA, making it a dominant economic strategy. Upon one-way sensitivity analysis, the model's results were sensitive to the reduction in index VTE hospitalization length-of-stay associated with rivaroxaban compared with enoxaparin + VKA. At a willingness-to-pay threshold of $50,000/QALY, probabilistic sensitivity analysis showed rivaroxaban to be cost-effective compared with enoxaparin + VKA approximately 76% of the time.

LIMITATIONS

The model did not account for the benefits associated with an oral and minimally invasive administration of rivaroxaban. 'Real-world' applicability is limited because data from the EINSTEIN trials were used in the model. Also, resource utilization and costs were based on the US healthcare system.

CONCLUSION

Rivaroxaban is a cost-effective option for anticoagulation treatment of acute VTE patients.

Economic evaluation of standard heparin and enoxaparin for prophylaxis against deep vein thrombosis in elective hip surgery

Deep vein thrombosis (DVT) is a common complication in patients undergoing elective hip surgery. Because of the associated risk of pulmonary embolism, prophylaxis with standard (unfractionated) heparin is becoming increasingly important. Recent clinical trials have shown a low molecular weight form of heparin, enoxaparin, to be more effective than standard heparin in preventing DVT, but the new drug is also more expensive. Data on clinical effectiveness and cost were combined in an economic evaluation of the two regimens. It was found that prophylaxis with enoxaparin would be expected to lead to a net saving of 20 pounds per patient. The economic results are sensitive to the costs of enoxaparin, the costs of drug administration and the probability of false clinical diagnosis of DVT or pulmonary embolism.

A cost-effectiveness model comparing rivaroxaban and dabigatran etexilate with enoxaparin sodium as thromboprophylaxis after total hip and total knee replacement in the irish healthcare setting

BACKGROUND

It has been estimated that major orthopaedic surgery has the highest risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) when compared with other surgery. Two new orally active anticoagulants have recently become licensed in Ireland for the primary prevention of venous thromboembolism in adult patients undergoing elective total hip replacement (THR) or total knee replacement (TKR). Rivaroxaban (Xarelto) is a direct factor Xa inhibitor and dabigatran etexilate (Pradaxa) is a prodrug of the active compound dabigatran, which inhibits thrombin.

OBJECTIVE

To evaluate the cost effectiveness of rivaroxaban and dabigatran etexilate compared with enoxaparin sodium for the prophylaxis of venous thromboembolism in patients undergoing elective THR and TKR in the Irish healthcare setting.

METHODS

The evaluation was conducted from the Irish health-payer perspective. A static decision-tree model was developed with a 180-day post-surgery time horizon. Separate models for the disease states THR and TKR were run to accommodate the different venous thromboembolism risks associated with each procedure. Outcome measures were QALYs and life-years gained (LYG). Costs were valued in euro, year 2008 values. One-way sensitivity analysis of all probabilities in the model was performed. A probabilistic sensitivity analysis using second-order Monte Carlo simulation was performed to determine the probability of cost effectiveness at euro 45,000 per QALY threshold.

RESULTS

In the THR base-case model, rivaroxaban dominated both dabigatran etexilate and enoxaparin sodium. The incremental cost-effectiveness ratios for dabigatran etexilate relative to enoxaparin were euro 23,934 per LYG and euro 17,835 per QALY. In the TKR base-case model, rivaroxaban dominated both dabigatran etexilate and enoxaparin sodium. Dabigatran etexilate also dominated enoxaparin sodium. In the one-way sensitivity analysis, the THR model was robust to all but four probability variations; the TKR model was robust to all variations. At a cost-effectiveness threshold of euro 45,000 per QALY, the probability that rivaroxaban was the most cost-effective strategy after THR was 39%, followed by dabigatran etexilate at 32% and enoxaparin sodium at 29%. The probability that rivaroxaban was the most cost-effective strategy after TKR was 46%, followed by dabigatran etexilate at 30% and enoxaparin sodium at 24%.

CONCLUSION

Base-case analysis indicates that when both rivaroxaban and dabigatran etexilate are compared with enoxaparin sodium, rivaroxaban is the less costly and more effective option after THR and TKR. Probabilistic sensitivity analysis indicates that rivaroxaban is the most cost-effective strategy at a cost-effectiveness threshold of euro 45,000 per QALY; however, there is uncertainty regarding this strategy being more cost effective than dabigatran etexilate when both are compared with enoxaparin sodium.

Comparison of dalteparin and enoxaparin for deep venous thrombosis prophylaxis in patients with spinal cord injury

OBJECTIVE

To determine differences between dalteparin and enoxaparin in patients with spinal cord injury.

DESIGN

This prospective, randomized, open-label study was performed as a multiple hospital trial in a large urban setting. A total of 100 patients with acute (<3 mo) spinal cord injury were recruited. A total of 95 patients met all inclusion criteria. Fifty received enoxaparin, and 45 received dalteparin. Main outcome measures included deep venous thrombosis, bleeding, compliance, Short Form-12 Health Status Survey, satisfaction, and medication/labor costs. Patients were randomized to receive 30 mg of enoxaparin subcutaneously every 12 hr or 5000 IU of dalteparin subcutaneously once daily. Prophylaxis was continued for 3 mo for motor-complete and 2 mo for motor-incomplete patients.

RESULTS

Six percent of the patients developed deep venous thrombosis while receiving enoxaparin and 4% while receiving dalteparin (chi2 = 0.44, df = 1, P = 0.51). Four percent developed bleeding while receiving dalteparin and 2% while receiving enoxaparin (chi2 = 0.13, df = 1, P = 0.72). No differences were noted in compliance, health status, or most of the satisfaction measures. It was, however, noted that after being discharged home, the patients receiving enoxaparin rated the shots significantly more inconvenient (two injections per day) compared with taking three pills per day, than those receiving dalteparin (one injection per day, P < 0.05). The cost of the medication was 1101 US dollars/mo for enoxaparin (two injections per day) and 750 US dollars/mo for dalteparin (one injection per day).

CONCLUSION

Similar compliance, health status, deep venous thrombosis, and bleeding rates were found between dalteparin and enoxaparin.

Results of an economic model to assess the cost-effectiveness of enoxaparin, a low-molecular-weight heparin, versus warfarin for the prophylaxis of deep vein thrombosis and associated long-term complications in total hip replacement surgery in the United States

BACKGROUND

Premature death due to pulmonary embolism is a short-term complication of deep vein thrombosis (DVT). The long-term clinical course after DVT can be further complicated by excess mortality, recurrent venous thromboembolism (VTE), and the post-thrombotic syndrome (PTS), which may produce sizable long-term economic burdens.

OBJECTIVE

The goal of this study was to determine the cost-effectiveness of the low-molecular-weight heparin (LMWH) enoxaparin versus warfarin for the universal prophylaxis of DVT and associated long-term complications in US patients undergoing total hip replacement surgery (THRS).

METHODS

A model was constructed to assess the long-term cost-effectiveness of the 2 treatments. Patients undergoing THRS were exposed to a short-term risk of developing a DVT. Patients surviving a DVT were exposed to increased risk of long-term complications of DVT, including PTS, recurrent VTE, and increased mortality. Published literature, augmented by expert opinion, served as input for the model's resource use and costs for DVT prophylaxis, clinical diagnosis, and treatment of DVT, VTE, and PTS.

RESULTS

When the analysis included only the short-term consequences of DVT, therapy with enoxaparin resulted in a net cost of $133 per patient and a net increase of 0.04 quality-adjusted life-years (QALYs) per patient. Thromboprophylaxis with enoxaparin versus warfarin resulted in $3733 per QALY saved. In contrast, when the long-term consequences of DVT were included, enoxaparin resulted in net lifetime savings of $89 per patient and net QALY benefits of 0.16 per patient.

CONCLUSIONS

To the best of our knowledge, this is the first US economic analysis comparing DVT prophylaxis with the LMWH enoxaparin versus warfarin that included the long-term complications of DVT. Our model suggests that use of enoxaparin in patients undergoing THRS reduces the economic burden associated with these long-term complications.

Economic analysis of low-dose heparin vs the low-molecular-weight heparin enoxaparin for prevention of venous thromboembolism after colorectal surgery

BACKGROUND

Low-dose heparin and low-molecular-weight heparin are effective strategies for preventing venous thromboembolism in colorectal surgery. The economic attractiveness of these 2 strategies in North America is unknown. We conducted an economic analysis of low-dose heparin calcium compared with enoxaparin sodium, a low-molecular-weight heparin, for thromboembolism prophylaxis after colorectal surgery.

METHODS

We used decision analysis, with an economic perspective of a third-party payer. Efficacy data were obtained from the Canadian Multicentre Colorectal Deep Vein Thrombosis Prophylaxis Trial and a literature review. Canadian costs for diagnosis and treatment of deep vein thrombosis (DVT), pulmonary embolism (PE), and major bleeding were obtained from chart review and a national hospital database of colorectal surgery; American costs were obtained from published literature. The main outcomes were incremental benefits (symptomatic DVTs, symptomatic PEs, and major bleeding events avoided) and incremental costs for every 1000 patients treated.

RESULTS

In the Canadian Colorectal Trial, the relative risk of DVT and PE for enoxaparin compared with low-dose heparin was 1.0 (95% confidence interval, 0.7-1.5), and the relative risk of major bleeding was 1.8 (95% confidence interval, 0.8-3.9). With the use of these data in the baseline analysis, a strategy of enoxaparin prophylaxis was associated with equal numbers of symptomatic DVTs and PEs, and an excess of 12 major bleeding episodes for every 1000 patients treated, with an additional cost of $86 050 (Canadian data) or $145 667 (US data). In a sensitivity analysis using optimal assumptions for efficacy and safety of enoxaparin (relative risk of DVT, 0.8; relative risk of PE, 0.4; relative risk of major bleeding, 1.0), a strategy of enoxaparin prophylaxis was associated with 0.8 fewer symptomatic DVT, 3 fewer symptomatic PEs, and equal numbers of major bleeding episodes for every 1000 patients treated, with an additional cost of $15 217 (Canadian data) or $107 614 (US data).

CONCLUSION

Although heparin and enoxaparin are equally effective, low-dose heparin is a more economically attractive choice for thromboembolism prophylaxis after colorectal surgery.

Will the use of low-molecular-weight heparin (enoxaparin) in patients with acute coronary syndrome save costs in Canada?

BACKGROUND

One-year follow-up data from the Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events (ESSENCE) trial show that use of low-molecular-weight heparin (enoxaparin) compared with unfractionated heparin in patients hospitalized with unstable angina or non-Q-wave myocardial infarction is associated with a 10% reduction in the cumulative 1-year risk of death, myocardial infarction, or recurrent angina. Given the higher acquisition cost of enoxaparin relative to unfractionated heparin, we assessed whether the reduced use of revascularization procedures and related care makes enoxaparin a cost-saving therapy in Canada.

METHODS AND RESULTS

We analyzed cumulative 1-year resource use data on the 1259 ESSENCE patients enrolled in Canadian centers (40% of the total ESSENCE sample). Patient-specific data on use of drugs, diagnostic cardiac catheterization, percutaneous transluminal coronary angioplasty, coronary artery bypass grafting, and hospital days were available from the initial hospital stay and cumulative to 1 year. Hospital resources were costed with the use of data from a teaching hospital in southern Ontario that is a participant in the Ontario Case Costing Project. During the initial hospital stay, use of enoxaparin was associated with reduced use of diagnostic catheterization and revascularization procedures, with the largest effect being reduced use of percutaneous transluminal coronary angioplasty (15.0% vs 10.6%; P =.03). At 1 year, the reduced risk and costs of revascularization more than offset increased drug costs for enoxaparin, producing a cost-saving per patient of $1485 (95% confidence interval $-93 to $3167; P =.06). Sensitivity analysis with lower hospital per diem costs from a community hospital in Ontario still predicts cost savings of $1075 per patient over a period of 1 year.

CONCLUSIONS

The acquisition and administration cost of enoxaparin is higher than for unfractionated heparin ($101 vs $39), but in patients with acute coronary syndrome, the reduced need for hospitalization and revascularization over a period of 1 year more than offsets this initial difference in cost. Evidence from this Canadian substudy of ESSENCE supports the view that enoxaparin is less costly and more effective than unfractionated heparin in this indication.

Pharmacoeconomic model of enoxaparin versus heparin for prevention of deep vein thrombosis after total hip replacement

The costs of heparin and enoxaparin to prevent deep vein thrombosis (DVT) after total hip replacement in the U.S. treatment environment were compared. A decision model was used in a pharmacoeconomic comparison of subcutaneous enoxaparin and subcutaneous heparin, each given for seven days, for the prophylaxis of DVT. In the model, three outcome pathways could follow prophylaxis: proximal DVT, distal DVT, and no DVT (but with a possible false-positive clinical diagnosis of DVT). Probabilities of thromboembolic events and major bleeding were derived from three randomized clinical trials. Account was also taken of the effects of pulmonary embolism (PE). Pharmacoeconomic studies and expert opinion were relied on for the model's principal resource-use categories and costs for DVT prophylaxis, clinical diagnosis of DVT and PE, and DVT and PE treatment. The outcome of choice for the model was the number of DVT events avoided. Regardless of the trial data used, the total mean cost of enoxaparin prophylaxis ($3336 to $3380) exceeded the cost of heparin prophylaxis ($3292 to $3330). However, enoxaparin was more cost-effective in avoiding DVT than heparin, irrespective of the trial on which the analysis was modeled. A sensitivity analysis involving length of hospital stay and length of prophylactic therapy showed the model to be robust and gave the advantage in all instances to enoxaparin in cost per DVT avoided. A model of enoxaparin versus heparin DVT prophylaxis after total hip replacement showed that enoxaparin was more costly than heparin in overall expected treatment costs but more cost-effective in the avoidance of DVT.

Country specific cost comparisons from multinational clinical trials using empirical Bayesian shrinkage estimation: the Canadian ASSENT-3 economic analysis

The growing number of multinational clinical trials in which patient-level health care resource data are collected have raised the issue of which is the best approach for making inference for individual countries with respect to the between-treatment difference in mean cost. We describe and discuss the relative merits of three approaches. The first uses the random effects pooled estimate from all countries to estimate the difference for any particular country. The second approach estimates the difference using only the data from the specific country in question. Using empirical Bayes estimation a third approach estimates the country-specific difference using a variance-weighted linear sum of the estimates provided by the other two approaches. The approaches are illustrated and compared using the data from the ASSENT-3 trial.

Prevention of deep-vein thrombosis following total hip replacement surgery with enoxaparin versus unfractionated heparin: a pharmacoeconomic evaluation

OBJECTIVE

To compare the use of healthcare services in patients receiving enoxaparin, a low molecular weight heparin versus those receiving unfractionated heparin as prophylaxis against deep-vein thrombosis (DVT) following total hip replacement surgery.

DESIGN

Economic evaluation undertaken in conjunction with a randomized, open-label, parallel group, Phase III clinical trial.

SETTING

32 US acute-care hospitals.

PATIENTS

607 patients undergoing elective total hip replacement.

INTERVENTIONS

Enoxaparin 30 mg q12h, enoxaparin 40 mg qd, or unfractionated heparin 5000 units q8h started within 24 hours following surgery and continued for 7 days.

MAIN OUTCOME MEASURES

(1) Use of selected tests and treatments for DVT; (2) use of selected tests and treatments related to postoperative bleeding; (3) length of stay in hospital; and (4) readmissions to hospital within 14 days.

RESULTS

Although the use of selected tests and treatments related to DVT or postoperative bleeding did not differ significantly between the three treatment groups, mean length of stay in the hospital (following the start of study therapy) was shorter among patients receiving enoxaparin 30 mg (9.5 days; p = 0.01) or 40 mg (9.9 days; p < 0.05) than those receiving unfractionated heparin (11.3 days). There was also a trend toward fewer hospital readmissions in both of the enoxaparin groups.

CONCLUSIONS

Compared with unfractionated heparin, use of enoxaparin following total hip replacement may decrease the risk of DVT and length of hospital stay.

Economic evaluation of the MEDENOX trial: a Canadian perspective. Medical Patients with Enoxaparin

OBJECTIVE

To perform an economic evaluation of the Prophylaxis in Medical Patients with Enoxaparin (MEDENOX) trial from a Canadian perspective.

METHOD

Using a decision tree model, cost effectiveness analysis was carried out to compare the costs and consequences of thromboprophylaxis using enoxaparin 40 mg with placebo in tertiary and community settings. From a third party payer's perspective, the model calculated the expected rate of symptomatic venous thromboembolism (VTE), and the total expected cost of prophylaxis and VTE management, including inpatient and outpatient treatment, professional fees and long term therapy. Data were derived directly from the MEDENOX trial. Costs are direct medical costs in year 2000 Canadian dollars.

RESULTS

In a tertiary setting in which the estimated inpatient to outpatient deep vein thrombosis treatment ratio was 10%:90%, the total expected cost per patient was 64 dollars in the enoxaparin group and 62 dollars in the placebo group. The expected symptomatic VTE rates were 0.8% and 3.1% in the enoxaparin and placebo groups, respectively. The incremental cost effectiveness of enoxaparin 40 mg versus placebo was 87 dollars/VTE avoided. In a community hospital setting (with a 50%:50% inpatient to outpatient deep vein thrombosis treatment ratio), the total expected cost per patient was 68 dollars in the enoxaparin group compared with 72 dollars in the placebo group, indicating that prophylaxis with enoxaparin 40 mg was cost saving. The model was sensitive to the inpatient to outpatient ratio. However, within each setting, the results were not sensitive to changes in key variables.

CONCLUSION

For patients hospitalized for acute respiratory failure, congestive heart failure or acute infectious disease and who are at moderate risk of developing VTE, thromboprophylaxis with enoxaparin 40 mg daily is a cost effective strategy in both tertiary and community settings.

Cost analyses of extended prophylaxis with enoxaparin after hip arthroplasty

Venous thromboembolic complications occur in 50% to 70% of patients undergoing total hip arthroplasty if no prophylactic regimen is used. Because enoxaparin and warfarin are useful for extended outpatient prophylaxis, the objective of this study was to determine which of these agents is most cost effective in preventing venous thromboembolic complications. A decision tree analysis was developed to simulate a hypothetical cohort of patients with total hip arthroplasty. The analysis considered home health care services to perform monitoring and compliance verification. Accounting for prophylactic failures and treatment complications, results showed that enoxaparin maintained a cost effective advantage over warfarin for extended prophylaxis in the time after discharge and total hip arthroplasty ranging from 19 to 31 days after the patient was discharged from the hospital. The duration of cost effectiveness of enoxaparin was reduced to 14 to 17 days when home care services were excluded. These results indicated that approximately 3 weeks of outpatient therapy with enoxaparin is cost effective. With the cornerstone of managed care being cost efficiency in the provision of quality care, this conclusion warrants the development of integrated care strategies for the patient having orthopaedic surgery to achieve cost effective patient management.

Potential clinical efficacy and cost benefit of a transesophageal echocardiography-guided low-molecular-weight heparin (enoxaparin) approach to antithrombotic therapy in patients undergoing immediate cardioversion from atrial fibrillation

An alternative clinical management strategy and cost analysis model is presented for patients with atrial fibrillation of >2 days' duration who may benefit from immediate cardioversion with self-administered low-molecular-weight heparin (enoxaparin) as a bridge antithrombotic therapy to warfarin, after a negative transesophageal echo-cardiography (TEE) screening for thrombus. Assuming no difference in stroke or bleeding rates, our cost minimization model shows that the TEE-guided enoxaparin treatment costs are $1353 lower per patient than an intravenous unfractionated heparin approach. Sensitivity analyses for stroke and bleeding reveal that the treatment-cost economic dominance of the TEE-guided enoxaparin approach may be enhanced by an expected improvement in clinical outcome.

Cost for inpatient care of venous thrombosis: a trial of enoxaparin vs standard heparin

BACKGROUND

Enoxaparin, a low-molecular-weight heparin administered to hospitalized patients once or twice daily, has shown efficacy and safety equivalent to unfractionated heparin in the treatment of acute venous thromboembolic disease. Although the cost of either enoxaparin regimen is greater than that of unfractionated heparin, the overall cost of care for each of these 3 treatment strategies is unknown.

METHODS

A cost minimization analysis of a 3-month, partially blinded, randomized, controlled efficacy and safety trial of anticoagulant therapy for deep vein thrombosis. Three hundred thirty-nine hospitalized patients with symptomatic lower extremity deep vein thrombosis were randomly assigned to initial therapy with subcutaneous enoxaparin either once (n = 112) or twice (n = 123) daily, or with dose-adjusted intravenous unfractionated heparin (n = 104), followed by long-term oral anticoagulant therapy. Estimated 1997 total cost from a third-party payer perspective for the 3-month episode of care was calculated by assigning standard unit costs to counts of medical resources used by each patient in the clinical trial.

RESULTS

Average total cost for the 3-month episode of care was similar across all 3 treatment regimens: once-daily dose of enoxaparin, $12,166 (95% confidence interval [CI], $10,744-$13,588); twice-daily dose of enoxaparin, $11,558 (95% CI, $10,201-$12,915); and unfractionated heparin, $12,146 (95% CI, $10,670-$12,622). Bootstrapped estimates and sensitivity analyses did not significantly change findings.

CONCLUSIONS

There was no significant difference in the overall cost for the 3-month episode of care for patients treated with either enoxaparin or unfractionated heparin. Additional acquisition costs for anticoagulant medication among patients treated with enoxaparin were offset by savings associated with lower incidence of hospital readmission and shorter duration of venous thromboembolism-related readmissions.

Cost effectiveness of rivaroxaban versus enoxaparin for prevention of post-surgical venous thromboembolism from a U.S. payer's perspective

BACKGROUND

Major orthopaedic surgery, such as total hip replacement (THR) and total knee replacement (TKR), is associated with an increased risk of venous thromboembolism (VTE).

OBJECTIVE

Clinical trials have demonstrated the efficacy of rivaroxaban, a once-daily, orally administered Factor Xa inhibitor, for the prevention of VTE in patients undergoing THR or TKR. This analysis evaluated the cost effectiveness of rivaroxaban compared with enoxaparin, from a U.S. payer's perspective.

METHODS

A decision-analytic model was developed to compare the costs and outcomes associated with rivaroxaban and enoxaparin for the prevention of VTE. The model replicated short-term clinical outcomes from the phase III RECORD trials. RECORD1 and RECORD2 compared rivaroxaban 10 mg daily (qd), given for 35 days, with enoxaparin 40 mg qd, given for 35 days or 10 to 14 days, respectively, in patients undergoing THR. RECORD3 compared 10 mg of rivaroxaban qd for 10 to 14 days versus 40 mg of enoxaparin qd for 10 to 14 days in patients undergoing TKR. The decision-analytic model also included data on long-term complications and sequelae as captured in observational studies and databases. It also included direct year 2010 medical costs over 1-year and 5-year time horizons. A series of sensitivity analyses were performed to determine the impact of different factors on the results of the model. Results of the cost-effectiveness analysis were reported in terms of symptomatic VTE events avoided.

RESULTS

Rivaroxaban was associated with cost savings of $US 511.93 per patient and prevented an average of 0.0145 symptomatic VTE events per patient in the THR population, compared with enoxaparin. For a TKR population, 10 to 14 days of rivaroxaban prophylaxis was associated with cost savings of $US 465.74 and prevented an average 0.0193 symptomatic VTE events per patient. Sensitivity analysis suggested that the results of the model were robust, with cost savings ranging from $US 133.96-629.57 in the THR population and $US 293.01-848.68 in the TKR population, depending on the variables used. Sensitivity analysis also suggested that the economic profile of rivaroxaban is improved when the time horizon of the model is extended from 1 year to 5 years. A probabilistic sensitivity analysis confirmed the findings of baseline results, showing that rivaroxaban was less costly and more effective in all model simulations for both populations.

CONCLUSIONS

This decision-analytic model analysis, from the U.S. payer's perspective, concluded that rivaroxaban may be cost saving in both the THR and the TKR populations, when compared with enoxaparin in the U.S.

Enoxaparin for thromboprophylaxis after major trauma: potential cost implications

OBJECTIVE

To determine the cost-effectiveness of enoxaparin compared with low-dose-heparin (LDH) for thromboprophylaxis after major trauma and to assess the economic significance of major bleeding as a complication of the use of low-molecular-weight heparin (LMWH).

DESIGN

Decision model analysis of the cost and efficacy of enoxaparin at preventing venous thromboembolism (VTE) and the risk and costs of major hemorrhage related to LMWH. The primary outcome was deep vein thromboses (DVTs) averted. Model estimates were based on data from prospective trials of LMWH and other studies of the financial ramifications of DVT and pulmonary embolism.

SETTING AND PATIENTS

Hypothetical cohort of 1,000 critically ill trauma patients requiring thromboprophylaxis.

INTERVENTIONS

In the model, patients were managed with either LMWH or LDH.

MEASUREMENTS AND MAIN RESULTS

The marginal cost-effectiveness of enoxaparin was calculated as the savings resulting from cases of DVT averted less the additional costs of both 1) LMWH and 2) major bleeding. This result is expressed as cost (or savings) per DVT prevented. Sensitivity analysis of the impact of the major clinical inputs on the cost-effectiveness was performed. The base case assumed that the incidence of DVT with LDH was 14.7%, that LMWH resulted in a relative risk reduction of DVT of 50%, but that enoxaparin nearly quadrupled the risk of bleeding. Despite the higher costs of enoxaparin, this tactic yielded a net savings of $391.23 per DVT prevented. For sensitivity analysis, model inputs were adjusted by 25% individually and then simultaneously. This demonstrated the model to be most sensitive to the calculated cost of a DVT. With the efficacy of LMWH reduced by 25% of the base-case estimate, enoxaparin resulted in a cost of $311.77 per DVT avoided. When all variables were skewed against LMWH, total outlays were trivial (approximately $85 per patient in the cohort). Neither the rate of increased bleeding with LMWH nor the costs incurred as a result of bleeding significantly altered the model's financial outcomes.

CONCLUSIONS

Reliance on enoxaparin represents a strategy for the prevention of VTE after trauma that may result in savings. Neither concerns about the higher cost of enoxaprin relative to LDH nor the financial implications of major bleeding should preclude the use of LWMH for thromboprophylaxis in trauma patients. Further studies are warranted to confirm the efficacy of enoxaparin.

A pharmacoeconomic assessment of enoxaparin and warfarin as prophylaxis for deep vein thrombosis in patients undergoing knee replacement surgery

This paper examines the relative cost-effectiveness of enoxaparin and warfarin as prophylactic therapy for the prevention of deep vein thrombosis (DVT) in patients undergoing knee replacement surgery in a managed care setting. Although enoxaparin is more expensive than warfarin, it is also more effective in the prevention of DVT after knee replacement surgery. To date there has been no comprehensive assessment of the cost-effectiveness of the alternative agents used for this purpose. This evaluation is undertaken using a decision model that contrasts enoxaparin and warfarin regimens. The model takes explicit account of the incidence of proximal DVT, distal DVT, pulmonary embolism (PE), and major bleeds. The probabilities of clinical events are taken from data from a published randomized, controlled, clinical trial. Key assumptions are that PEs derive only from asymptomatic proximal DVTs and that a false-positive diagnosis of DVT is made in 10% of cases. Unit resource cost data are taken from pharmacoeconomic studies of DVT prophylaxis in hip replacement surgery. The analysis focuses on the actual or expected cost of prophylactic treatment using enoxaparin as opposed to warfarin and, as appropriate measures of cost-effectiveness, the cost per DVT event avoided and the cost per incidence of PE avoided. The expected cost of warfarin prophylaxis is $105 less per patient than that of enoxaparin. In terms of expected cost per DVT event avoided, enoxaparin prophylaxis is $2525 less than for warfarin; in terms of expected cost per PE avoided, it is $87,201 less. Enoxaparin is more cost-effective than warfarin in terms of both DVT events and PEs avoided in patients who have undergone knee replacement surgery.

The role of low-molecular-weight heparin in the management of acute coronary syndromes

A substantial number of clinical studies have consistently demonstrated that low-molecular-weight heparin (LMWH) compounds are effective and safe alternative anticoagulants to unfractionated heparins (UFHs). They have been found to improve clinical outcomes in acute coronary syndromes and to provide a more predictable therapeutic response, longer and more stable anticoagulation, and a lower incidence of UFH-induced thrombocytopenia. Of the several LMWH agents that have been studied in large clinical trials, including enoxaparin, dalteparin, and nadroparin, not all have shown better efficacy than UFH. Enoxaparin is the only LMWH compound to have demonstrated sustained clinical and economic benefits in comparison with UFH in the management of unstable angina/ non-ST-segment elevation myocardial infarction (NSTEMI). Also, LMWH appears to be a reliable and effective antithrombotic treatment as adjunctive therapy in patients undergoing percutaneous coronary intervention. Clinical trials with enoxaparin indicate that LMWH is effective and safe in this indication, with or without the addition of a glycoprotein IIb/IIIa inhibitor. The efficacy demonstrated by enoxaparin in improving clinical outcomes in unstable angina/NSTEMI patients has led to investigations of its role in the management of ST-segment elevation myocardial infarction. Initial results are very encouraging, and they indicate that enoxaparin may potentially substitute for UFH as adjunctive therapy in fibrin-specific thrombolytic regimens and improve coronary reperfusion rates in streptokinase-based regimens.

Economic evaluation of enoxaparin for the prevention of venous thromboembolism in acutely ill medical patients

OBJECTIVE

To conduct an economic evaluation of the prevention of venous thromboembolism in acutely ill medical patients.

METHOD

We used a previously described economic model created in the context of the UK National Health Service and applied it to St. Thomas' Hospital, London. A clinical review to determine the number of medical admissions that would require thromboprophylaxis at St. Thomas' Hospital, based on the inclusion criteria of a medical thromboprophylaxis trial (MEDENOX), was conducted. Costs and effectiveness were determined, based on the provision of thromboprophylaxis to 2000 medical patients.

RESULTS

Comparing treatment with low-molecular-weight heparin (enoxaparin, 40 mg once daily), unfractionated heparin (5000 IU twice daily), or no prophylaxis, the highest cost of thromboprophylaxis was associated with unfractionated heparin (199,000 pounds sterling = 4306,000 Euros), compared with enoxaparin (198,000 pounds sterling = 305,000 Euros) or no prophylaxis (176,000 pounds sterling = 271,000 Euros). The model suggested that enoxaparin thromboprophylaxis would result in fewer thromboembolic-related events. Using sensitivity analysis, incorporating certain St. Thomas'-specific costs showed enoxaparin compared with unfractionated heparin or no thromboprophylaxis was cost saving. The cost savings of 65,000 pounds sterling ( = 100,000 Euros) and 31,000 pounds sterling ( = 48,000 Euros) respectively are based on maximum uptake of thromboprophylaxis.

CONCLUSIONS

The graded implementation of enoxaparin thromboprophylaxis over a four-year period would require funding redistribution. The funding Health Authority would save overall but St. Thomas' would require an increase in drug expenditure across the clinical directorates of 35,000 pounds sterling ( = 54,000 Euros) after 4 years.

Fondaparinux sodium compared with enoxaparin sodium: a cost-effectiveness analysis

INTRODUCTION

Patients undergoing major orthopedic surgery face considerable risk of venous thromboembolism (VTE), which may be fatal unless they receive prophylactic treatment. Fondaparinux sodium is a new antithrombotic agent that is indicated for prophylaxis of VTE after major orthopedic surgery. This paper presents a cost-effectiveness analysis of fondaparinux sodium and enoxaparin sodium, the latter being the most commonly used agent for prophylaxis of VTE.

METHODS

The analysis is based on an international simulation model, using Norwegian unit costs, and Norwegian data of 55 000 patients undergoing orthopedic surgery between 1999 and 2001. We estimated the expected incidence of VTE and VTE-related deaths, and expected costs of VTE-related care for each of the two prophylactic agents for different periods.

RESULTS AND CONCLUSION

The results indicate that fondaparinux sodium is likely to be more effective than enoxaparin sodium in preventing the incidence of VTE. By day 90, fondaparinux sodium is expected to avoid 180 more VTE events, and between 8 and 33 more VTE-related deaths per 10,000 patients than enoxaparin sodium. Fondaparinux sodium is also a cost-saving option in short follow-up periods for hip fracture surgery. For extended follow-up periods (i.e. 5 years), fondaparinux sodium is also likely to represent the lower cost treatment option after total knee and hip replacement. The sensitivity analyses show that the main results are robust to changes in the most important parameters. Results are, however, sensitive to the price difference between the two drugs.

A cost-effectiveness analysis of fondaparinux sodium compared with enoxaparin sodium as prophylaxis against venous thromboembolism: use in patients undergoing major orthopaedic surgery

OBJECTIVE

To determine the cost effectiveness of fondaparinux sodium compared with enoxaparin sodium for prophylaxis against venous thromboembolism in patients undergoing major orthopaedic surgery.

METHODS

Using a cohort simulation model, two primary analyses were conducted from the perspective of the US healthcare payer. Probabilities for a trial-based analysis were obtained from patients participating in the fondaparinux clinical trial programme supplemented with data from published literature. Probabilities for a label-based analysis were estimated for a hypothetical cohort of US patients receiving either fondaparinux or enoxaparin as recommended by US FDA-approved labelling. Resource use and costs were obtained from large US healthcare databases. Outcome measures were rates of symptomatic thromboembolic events and healthcare costs. Costs were in 2003 values.

RESULTS

In the trial-based analysis, fondaparinux was estimated to prevent 15.1 symptomatic venous thromboembolic events (per 1,000 patients) at 3 months for patients undergoing major orthopaedic surgery compared with enoxaparin. The cost savings (per patient) of using fondaparinux over enoxaparin are US 61 dollars at 30 days, US 89 dollars at 3 months, and US 155 dollars at 5 years. In the label-based analysis, fondaparinux was estimated to prevent 17.8 venous thromboembolic events (per 1,000 patients) at 3 months compared with enoxaparin, producing savings per patient of US 25 dollars at discharge, US 112 dollars over 1 month, US 141 dollars over 3 months and US 234 dollars over 5 years. Results remain robust to clinically plausible variation in input parameters and assumptions.

CONCLUSION

Our model suggests that fondaparinux, when compared with the current standard regimen of enoxaparin for prophylaxis of venous thromboembolism in major orthopaedic surgery, improves outcomes and is cost saving from a US healthcare-payer perspective over the broad range of assumptions evaluated.