Major bleeding rates after prophylaxis against venous thromboembolism: Systematic review, meta-analysis, and cost implications

Venous thromboembolism in benign esophageal surgery patients: potential cost effectiveness of Caprini risk stratification

BACKGROUND

The Caprini risk assessment model (RAM) stratifies surgical patients for prescription of post-discharge extended heparin prophylaxis to reduce post-operative venous thromboembolism (VTE) events. The average cost for treatment of a VTE event is $15,123. The 30-day post-operative VTE rate after benign esophageal procedures is < 0.8% per the Society of Thoracic Surgeons database. We hypothesized that the financial cost of selective extended prophylaxis in patients undergoing surgery for benign esophageal disease would exceed the cost of treating these rare events and therefore use of risk stratification for extended prophylaxis would not be beneficial.

METHODS

All patients undergoing operations for benign esophageal pathology from July 2014 to May 2019 were reviewed. Patients designated as moderate or high risk for VTE were prescribed a 10- or 30-day post-operative course of extended prophylaxis with low-molecular weight heparin (LMWH). VTE and adverse bleeding events were recorded for the 60-day post-operative period. The cost of LMWH was provided by the institution pharmacy.

RESULTS

Records from 154 patients were eligible for review. Caprini RAM was used for all patients with the following distribution of risk categories: low = 64.9% (100/154); moderate = 31.8% (49/154); and high = 3.2% (5/154). The average cost of extended prophylaxis at discharge for the moderate-risk group was $121.23, while the high-risk group was $446.46. There were no 60-day VTE or adverse bleeding events recorded.

CONCLUSIONS

The majority of patients undergoing surgical therapy were at low risk of post-operative VTE event, with only 35% requiring extended VTE prophylaxis at time of discharge. When compared with the average cost of treatment for a VTE event, the cost of extended prophylaxis per patient in moderate or high-risk groups is substantially lower. In the era of cost-containment, risk stratification and extended prophylaxis may reduce healthcare costs and warrant future investigations.

Incidence and Risk Factors of Symptomatic Venous Thromboembolism Following Foot and Ankle Surgery

BACKGROUND:

The incidence rate of venous thrombotic events (VTEs) following foot and ankle surgery is low. Currently, there is no consensus regarding postoperative prophylaxis or evidence to support risk stratification.

METHODS:

A 2-part study assessing the incidence and factors for the development of VTE was conducted: (1) a retrospective observational cohort study of 22 486 adults to calculate the overall incidence following foot and/or ankle surgery from January 2008 to May 2011 and (2) a retrospective matched case-control study to identify risk factors for development of VTE postsurgery. One control per VTE case matched on age and sex was randomly selected from the remaining patients.

RESULTS:

The overall incidence of VTE was 0.9%. Predictive risk factors in bivariate analyses included obesity, history of VTE, history of trauma, use of hormonal replacement or oral contraception therapy, anatomic location of surgery, procedure duration 60 minutes or more, general anesthesia, postoperative nonweightbearing immobilization greater than 2 weeks, and use of anticoagulation. When significant variables from bivariate analyses were placed into the multivariable regression model, 4 remained statistically significant: adjusted odds ratio (aOR) for obesity, 6.1; history of VTE, 15.7; use of hormone replacement therapy, 8.9; and postoperative nonweightbearing immobilization greater than 2 weeks, 9.0. The risk of VTE increased significantly with 3 or more risk factors ( P = .001).

CONCLUSION:

The overall low incidence of VTE following foot and ankle surgery does not support routine prophylaxis for all patients. Among patients with 3 or more risk factors, the use of chemoprophylaxis may be warranted.

LEVEL OF EVIDENCE:

Level III, retrospective case series.

Graduated compression stockings for the prevention of deep-vein thrombosis in postoperative surgical patients: a systematic review and economic model with a value of information analysis

BACKGROUND

Deep-vein thrombosis (DVT) can occur in surgical patients. Routine prophylaxis can be pharmacological and/or mechanical [e.g. graduated compression stockings (GCSs)]. GCSs are available in knee length or thigh length.

OBJECTIVE

To establish the expected value of undertaking additional research addressing the relative effectiveness of thigh-length GCSs versus knee-length GCSs, in addition to pharmacoprophylaxis, for prevention of DVT in surgical patients.

DESIGN

Systematic review and economic model, including value of information (VOI) analysis.

REVIEW METHODS

Randomised controlled trials (RCTs) assessing thigh- or knee-length GCSs in surgical patients were eligible for inclusion. The primary outcome was incidence of DVT. DVT complications and GCSs adverse events were assessed. Random-effects meta-analysis was performed. To draw on a wider evidence base, a random-effects network meta-analysis (NMA) was undertaken for the outcome DVT. A review of trials and observational studies of patient adherence was also conducted. A decision-analytic model was developed to assess the cost-effectiveness of thigh- and knee-length GCSs and the VOI.

RESULTS

Twenty-three RCTs were included in the review of effectiveness. There was substantial variation between trials in terms of the patient characteristics, interventions and methods of outcome assessment. Five trials comparing knee-length with thigh-length GCSs with or without pharmacoprophylaxis were pooled; the summary estimate of effect indicated a non-significant trend favouring thigh-length GCSs [odds ratio (OR) 1.48, 95% confidence interval (CI) 0.80 to 2.73]. Thirteen trials were included in the NMA. In the base-case analysis, thigh-length GCSs with pharmacoprophylaxis were more effective than knee-length GCSs with pharmacoprophylaxis (knee vs. thigh OR 1.76, 95% credible interval 0.82 to 3.53). Overall, thigh-length stockings with pharmacoprophylaxis was the most effective treatment, with a 0.73 probability of being the most effective treatment in a new trial of all the treatments. Patient adherence was generally higher with knee-length GCSs, and patients preferred knee-length GCSs. Thigh-length GCSs were found to be cost-effective in all but the subgroup with the lowest baseline risk, although the absolute differences in costs and effects were relatively small. The expected value of perfect information ranged from £0.2M to £178.0M depending on the scenario and subgroup. The relative effect parameters had the highest expected value of partial perfect information and ranged from £2.0M to £39.4M. The value of further research was most evident in the high-risk subgroups.

LIMITATIONS

There was substantial variation across the included trials in terms of patient and intervention characteristics. Many of the included trials were old and poorly reported, which reduces the reliability of the results of the review.

CONCLUSIONS

Given that the results from both the standard meta-analysis and the NMA lacked precision (CIs were wide) owing to the heterogeneous evidence base, a new definitive trial in high-risk patients may be warranted. However, the efficiency of any further research (i.e. whether this represents value for money) is dependent on several factors, including the acquisition price of GCSs, expected compliance with thigh-length GCSs wear, and whether or not uncertainty can be resolved around possible effect modifiers, as well as the feasibility and actual cost of undertaking the proposed research.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014007202.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Meta-analysis and suggested guidelines for prevention of venous thromboembolism (VTE) in foot and ankle surgery

PURPOSE

To perform a meta-analysis investigating venous thromboembolism (VTE) following isolated foot and ankle surgery and propose guidelines for VTE prevention in this group of patients.

METHODS

Following a PRISMA compliant search, 372 papers were identified and meta-analysis performed on 22 papers using the Critical Appraisal Skills Programme and Centre for Evidence-Based Medicine level of evidence.

RESULTS

43,381 patients were clinically assessed for VTE and the incidence with and without chemoprophylaxis was 0.6% (95% CI 0.4-0.8%) and 1% (95% CI 0.2-1.7%), respectively. 1666 Patients were assessed radiologically and the incidence of VTE with and without chemoprophylaxis was 12.5% (95% CI 6.8-18.2%) and 10.5% (95% CI 5.0-15.9%), respectively. There was no significant difference in the rates of VTE with or without chemoprophylaxis whether assessed clinically or by radiological criteria. The risk of VTE in those patients with Achilles tendon rupture was greater with a clinical incidence of 7% (95% CI 5.5-8.5%) and radiological incidence of 35.3% (95% CI 26.4-44.3%).

CONCLUSION

Isolated foot and ankle surgery has a lower incidence of clinically apparent VTE when compared to general lower limb procedures, and this rate is not significantly reduced using low molecular weight heparin. The incidence of VTE following Achilles tendon rupture is high whether treated surgically or conservatively. With the exception of those with Achilles tendon rupture, routine use of chemical VTE prophylaxis is not justified in those undergoing isolated foot and ankle surgery, but patient-specific risk factors for VTE should be used to assess patients individually.

LEVEL OF EVIDENCE

II.

Effect of medical thromboprophylaxis on mortality from pulmonary embolus and major bleedingy

BACKGROUND

Several studies have failed to discover a beneficial effect of medical thromboprophylaxis on mortality.

AIMS

To examine the relative influence of acute fatal pulmonary embolism (PE) and fatal major haemorrhage on overall mortality in medical patients treated with low molecular weight heparin (LMWP) for prophylaxis.

METHODS

The author compared deaths from the above factors using data from a recent Cochrane Collaboration meta-analysis. Data from trials satisfying the criteria of the Cochrane analysis plus additional exclusions to avoid bias were pooled to produce point estimates of mortality from PE and major bleeds to estimate net mortality benefit. Estimates were then subject to limited sensitivity analysis based on reported epidemiological data.

RESULTS

Reported PE and major bleeds were 0.44 per cent and 0.27 per cent, respectively. The corresponding case-specific mortality rates were 30.8 per cent and 12.8 per cent and the relative risk reduction (RRR) for PE was 23.2 per cent. Estimated deaths from major bleeds exceeded PE deaths avoided by a small margin (3/100,000 patients given prophylaxis). This excess increased to 30/100,000 when more plausible literature values for PE case fatality rates were applied.

CONCLUSION

Medical thromboprophylaxis has a finely balanced effect on mortality but may increase it. Such an effect would explain the failure to discover a mortality benefit from medical thromboprophylaxis. Further work, including a formal meta-analysis and additional clinical studies, is required to confirm this picture.

Low incidence of symptomatic thromboembolic events after total ankle arthroplasty without routine use of chemoprophylaxis

BACKGROUND

There is little evidence regarding the incidence of symptomatic venous thromboembolism (VTE) following total ankle arthroplasty (TAA) to allow formulation of treatment recommendations. The purpose of this study was to determine the incidence of symptomatic VTE events after TAA without use of chemoprophylaxis and to identify risk factors contributing to the occurrence of VTEs.

METHODS

We conducted a retrospective chart review of 637 patients (664 ankles) who received a TAA between May 2007 and January 2014 and had a minimum follow-up of 3 months. Chemoprophylaxis was prescribed only in the setting of a history of VTE or active coagulopathy. Patients were continued on chemoprophylactic agents if they were taking these medications preoperatively. A VTE event was defined when clinical signs and symptoms of deep venous thrombosis (DVT) were confirmed with use of Doppler ultrasonography or pulmonary embolism was confirmed with the use of a computed tomography scan. Routine screening for VTE was not performed.

RESULTS

The overall incidence of clinically detected VTE events was 0.60% (4/664), with 0.45% (3 patients) developing a DVT and 0.15% (1 patient) developing a nonfatal pulmonary embolism. Moreover, we identified a subset of 434 patients without identifiable preoperative risk factors who were not taking chemoprophylaxis preoperatively and were not prescribed chemoprophylaxis postoperatively. Two of these patients developed a DVT postoperatively (0.46%). Given the low incidence of clinically detected VTE, no significant correlation could be identified between the occurrence of VTE events and risk factors.

CONCLUSIONS

Our results suggest that clinically detectable VTE after TAA is uncommon. Patients without identifiable risk factors do not appear to require chemoprophylaxis following TAA. We recommend continuation of antiplatelet or anticoagulation therapy in patients who are taking these medications preoperatively and the initiation of chemoprophylaxis postoperatively in patients with known risk factors for VTE.

LEVEL OF EVIDENCE

Level IV, case series.

Thromboembolic prophylaxis in total joint arthroplasty

Approximately 775,000 hip and knee arthroplasties are performed yearly in the United States, with a dramatic increase expected. Patients having hip and knee arthroplasties are at high risk of developing a venous thromboembolism. The American College of Chest Physicians (ACCP) and the American Academy of Orthopedic Surgeons (AAOS) have updated guidelines, which outline new prophylactic strategies. Factor Xa inhibitor rivaroxaban has a new recommendation by ACCP and is gradually being adopted by the joint arthroplasty community as an effective oral agent. Other more well-known agents including warfarin, low-molecular-weight heparin, aspirin, and fondaparinux continue to be options for prophylaxis. While the goal of prophylaxis continues to be the prevention of venous thromboemboli and pulmonary emboli, it is important to consider the increased bleeding risk associated with their use. The most recent ACCP and AAOS guidelines give clinicians a greater autonomy in choosing a prophylactic agent with greater emphasis placed on dialogue between the surgeon and patient as to the choice of prophylaxis.

The incidence of thromboembolic events in surgically treated ankle fracture

BACKGROUND

Thromboembolic events occur following musculoskeletal injury, and some have serious sequelae, including death. The purpose of this study was to determine the incidence of thromboembolic events and its relationship with risk factors in ambulatory patients with ankle fracture requiring open reduction and internal fixation.

METHODS

We conducted a retrospective chart review of 2478 patients who underwent open reduction and internal fixation of an ankle fracture at any one of three university hospitals between January 1, 1997, and April 30, 2005. One thousand five hundred and forty patients meeting the inclusion criteria and with complete records (minimum follow-up, six months) were identified. The median age of the patients at the time of surgery was forty-six years, and there was an equal proportion of male and female patients. Fracture types included 45% unimalleolar fractures, 31% bimalleolar, and 24% trimalleolar. Charts were reviewed to identify thromboembolic events, risk factors (neoplasia, hormone use, pregnancy, blood dyscrasia, history of a previous thromboembolic event, a current history of smoking, obesity, dyslipidemia, atherosclerotic vascular disease, or paralysis), and use of thromboprophylactic agents. A thromboembolic event was defined as symptomatic when deep venous thrombosis was confirmed with use of Doppler ultrasonography or when pulmonary embolism was confirmed with use of ventilation and perfusion scintigraphy or helical computed tomography.

RESULTS

The incidence of thromboembolic events was 2.99% (forty-six patients), with 2.66% (forty-one patients) involving a deep venous thrombosis and 0.32% (five patients) involving a nonfatal pulmonary embolism. There were no fatal pulmonary emboli recorded. The incidence did not differ among hospitals. Of the 1540 patients, 16.43% received thromboprophylaxis during their hospital stay and for six weeks (for the 10.78% taking low-molecular-weight heparin) or three months (for the 5.65% taking warfarin) after discharge without significantly modifying the incidence of thromboembolic events (2.56% vs. 2.37%, relative risk = 0.91). However patients with one or more risk factors had a greater risk of a thromboembolic event than did patients with no risk factors (3.59% vs. 2.38%, respectively; relative risk = 0.66). The use of thromboprophylaxis had no apparent impact on the occurrence of thromboembolic events in patients who did or did not have risk factors (3.68% vs. 3.55%, respectively; relative risk = 0.96). No significant correlation could be identified between the occurrence of thromboembolic events and fracture types, age, or sex.

CONCLUSIONS

Clinically detectable thromboembolic events after surgical treatment of ankle fractures are uncommon and do not appear to be influenced by the use of thromboprophylaxis. Patients with risk factors appear to be at higher risk for these events, but there is a need for prospective studies to determine the efficacy of thromboprophylaxis after surgical treatment of ankle fractures.

In-hospital risk of venous thromboembolism and bleeding and associated costs for patients undergoing total hip or knee arthroplasty

OBJECTIVE

Benefits of anti-coagulation for venous thromboembolism (VTE) prevention in total hip and knee arthroplasty (THA/TKA) may be offset by increased risk of bleeding. The aim was to assess in-hospital risk of VTE and bleeding after THA/TKA and quantify any increased costs.

METHODS

Healthcare claims from the Premier Perspective(TM) Comparative Hospital Database (January 2000-September 2008) were selected for subjects ≥ 18 years with ≥ 1 diagnosis code for THA/TKA. VTE was defined as ≥ 1 code for deep vein thrombosis or pulmonary embolism. Bleeding was classified as major/non-major. Incremental in-hospital costs associated with VTE and bleeding were calculated as cost differences between inpatients with VTE or bleeding matched 1:1 with inpatients without VTE or bleeding.

RESULTS

A total of 820,197 inpatient stays were identified: 8042 had a VTE event and 7401 a bleeding event (2740 major bleeding). The risks of VTE, any bleeding, and major bleeding were 0.98, 0.90, and 0.33/100 inpatient stays, respectively. Mean incremental in-hospital costs per inpatient were $2663 for VTE, $2028 for bleeding, and $3198 for major bleeding.

LIMITATIONS

These included possible inaccuracies or omissions in procedures, diagnoses, or costs of claims data; no information on the amount of blood transfused or decreases in the hemoglobin level to evaluate bleeding event severity; and potential biases due to the observational design of the study.

CONCLUSIONS

In-hospital risk and incremental all-cause costs with THA/TKA were higher for VTE than for bleeding. Despite higher costs, major bleeding occurred less frequently than VTE, suggesting a favorable benefit/risk profile for VTE prophylaxis in THA/TKA.

Clinical burden of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism (PE), is a major cause of morbidity and mortality. VTE is a common disorder, with an estimated annual incidence of approximately 5-12 persons per 10,000. The prognosis for patients who develop VTE is exacerbated by the risk of recurrent VTE, post-thrombotic syndrome and chronic pulmonary hypertension as a long-term complication of PE.

SCOPE

To assess the clinical burden of VTE a literature search was carried out to identify references published between 1997 and 2008 using Medline, the Cochrane Library and the Health Economic Evaluations Database.

FINDINGS

VTE is a frequent clinical problem, both in the general population, in hospitalised patients and in particular in patients undergoing major orthopaedic surgery, after trauma, or those with malignancy, and related complications are frequent. VTE imposes significant consequences on patients and on the healthcare systems that support them - extending hospital stays and precipitating additional hospitalisations. Limitations of the review are that the sources quoted may not adequately reflect all publications and all perspectives on the topic.

CONCLUSIONS

Even among high-risk groups it is not possible to identify individuals who will go on to develop VTE, and, therefore, thromboprophylaxis is a recommended component of the management of high-risk patients. Ensuring patients receive safe, effective, easily administered antithrombotic therapy both in hospital and post-discharge, for a sufficient length of time, should be central to any strategy to reduce incident or recurrent VTE and minimise the risk of long-term complications.

Complications related to deep venous thrombosis prophylaxis in trauma: a systematic review of the literature

Deep venous thrombosis prophylaxis is essential to the appropriate management of multisystem trauma patients. Without thromboprophylaxis, the rate of venous thrombosis and subsequent pulmonary embolism is substantial. Three prophylactic modalities are common: pharmacologic anticoagulation, mechanical compression devices, and inferior vena cava filtration. A systematic review was completed using PRISMA guidelines to evaluate the potential complications of DVT prophylactic options. Level one evidence currently supports the use of low molecular weight heparins for thromboprophylaxis in the trauma patient. Unfortunately, multiple techniques are not infrequently required for complex multisystem trauma patients. Each modality has potential complications. The risks of heparin include bleeding and heparin induced thrombocytopenia. Mechanical compression devices can result in local soft tissue injury, bleeding and patient non-compliance. Inferior vena cava filters migrate, cause inferior vena cava occlusion, and penetrate the vessel wall. While the use of these techniques can be life saving, they must be appropriately utilized.

Cost-effectiveness of warfarin: trial versus "real-world" stroke prevention in atrial fibrillation

BACKGROUND AND PURPOSE

Previous cost-effectiveness analyses analyzed warfarin for stroke prevention in randomized trial settings. Given the complexities of warfarin treatment, cost-effectiveness should be examined within a real-world setting.

METHODS

Our model followed patients with atrial fibrillation at moderate to high risk of stroke through primary and recurrent ischemic stroke, hemorrhages--intracranial and extracranial, and the resulting disability. Four scenarios were examined: (1) all patients start on warfarin with perfect control, that is, international normalized ratio (INR) values always within range; (2) all patients start on warfarin with trial-like control, where INR can fall outside the recommended range; (3) all patients start on warfarin with real-world INR control; and (4) real-world prescription (and control) of warfarin, aspirin, or neither for warfarin-eligible patients. Reported warfarin discontinuation rates were used. Main outcomes were total number of events, quality adjusted life years, and costs in a US setting.

RESULTS

The total number of primary and recurrent ischemic strokes in a 1,000-patient cohort (age 70 years, lifetime analysis) was 626, 832, 984, and 1,171 in scenarios 1 to 4, respectively. The corresponding mean quality adjusted life years per patient were 7.21, 6.92, 6.75, and 6.67 for scenarios 1 to 4, respectively. Costs per patient were $68,039, $77,764, $84,518, and $87,248 in scenarios 1 to 4, respectively. If "perfect" adherence to warfarin was assumed, except for discontinuations for clinical reasons, strokes would decrease to 503, 737, 909, and 1,120 in scenarios 1 to 4, respectively.

CONCLUSIONS

Clinical and cost outcomes are strongly dependent on the quality of anticoagulation and rates of warfarin discontinuation. Clinicians should work to improve both. Policy makers should use real-world INR control and warfarin discontinuation rates when assessing cost-effectiveness.

Economic evaluation of dabigatran etexilate for the prevention of venous thromboembolism after total knee and hip replacement surgery

OBJECTIVE

This was an evaluation of the cost-effectiveness of oral dabigatran etexilate compared with subcutaneous low-molecular-weight heparin (enoxaparin) for the prevention of venous thromboembolism (VTE) after total knee replacement (TKR) and total hip replacement (THR) surgery from the perspective of the UK National Health Service.

METHODS

Dabigatran etexilate (220 mg once daily) was compared with enoxaparin (40 mg once daily) in patients undergoing TKR (duration of prophylaxis, 6-10 days) and THR (duration of prophylaxis, 28-35 days). The 10-week acute postsurgical phase was modeled using a decision tree. A Markov process (1-year cycle length) was used to model long-term events (recurrent VTE, postthrombotic syndrome, and consequences of intracranial hemorrhage) for patients' remaining lifetimes. Relative risks for VTE and bleeding events were derived from 2 Phase III studies that compared dabigatran etexilate with enoxaparin 40 mg once daily. The probabilities of long-term events were estimated using data from published longitudinal studies.

RESULTS

Rates of VTE and bleeding events did not differ significantly between dabigatran etexilate and enoxaparin. Dabigatran etexilate was less costly than enoxaparin in TKR and substantially less costly in THR, primarily due to differences in administration costs. The cost of prophylaxis for THR patients, including drugs and administration costs, was estimated at pound 137 for dabigatran etexilate and pound 237 for enoxaparin ( pound 7 for nursing time during the hospital stay, pound 91 for nurse home visits for administration after hospital discharge, and an additional pound 2 in drug costs). At a willingness-to-pay threshold of pound 20,000 per quality-adjusted life-year, the probability of cost-effectiveness for dabigatran etexilate was 75% in TKR and 97% in THR. These results were robust across a range of sensitivity analyses.

CONCLUSION

From the perspective of the UK National Health Service, thromboprophylaxis with dabigatran etexilate was cost-saving compared with enoxaparin 40 mg once daily, with comparable efficacy and safety profiles.

A 10-year analysis of venous thromboembolism on the surgical service: the effect of practice guidelines for prophylaxis

BACKGROUND

There is a national effort to decrease the incidence of venous thromboembolism (VTE) in surgical patients by encouraging compliance with established guidelines for prophylaxis. Reported compliance with these guidelines has been poor. The outcome of noncompliance in terms of morbidity and mortality in surgical patients is unknown. We sought to determine if there has been a decrease in the incidence of symptomatic VTE since implementation of the guidelines and whether there has been compliance with the guidelines in individual patients; we also analyzed the outcome of a cohort with VTE.

METHODS

We reviewed the records of all patients with symptomatic VTE on 3 surgery services over the 10-year period since initial publication of the guidelines. We determined in each patient whether there was compliance with the guidelines. We weighted the morbidity of each episode of VTE based on the likelihood of short-term mortality and long-term morbidity to determine the disease burden.

RESULTS

Of 37,615 patients, 172 developed a VTE (0.46%), and the incidence increased gradually over the years of the study. There was partial or complete compliance with the guidelines in 84% of the patients, but 37% of the VTEs were considered to be preventable. The disease burden was greatest in the higher-risk patients-there were 20 deaths (6%), 4 of which were caused by a pulmonary embolus.

CONCLUSIONS

Despite one of the highest published rates of compliance with the guidelines for prophylaxis, the rate of symptomatic VTE is increasing.

Thromboprophylaxis in medically ill patients at risk for venous thromboembolism

PURPOSE

According to guidelines from the American College of Chest Physicians, low-molecular-weight heparin (LMWH) and unfractionated heparin (UFH) should be prescribed to medical (nonsurgical) patients at high risk of venous thromboembolism. Thromboprophylaxis and mortality rates were determined in medical inpatients with indications for thromboprophylaxis. Cost differences between patient groups were investigated and are discussed.

SUMMARY

Using Solucient's ACTracker Inpatient Database, medical discharges between January 2001 and December 2004 were extracted and patients who had indications for thromboprophylaxis (acute myocardial infarction, ischemic stroke, cancer, heart failure, or severe lung disease) were identified. Patients < 40 years or with deep-vein thrombosis or pulmonary embolism, active peptic ulcer, malignant hypertension, blood disease, HIV infection, or intubation of gastrointestinal or respiratory tract were excluded. Rates of thromboprophylaxis and mortality were compared between groups. Mean total drug costs and hospital costs per patient discharge were compared between patient groups. Of 12,887,080 medical discharges extracted from 330 hospitals, there were 2,367,362 patients with indications for thromboprophylaxis. Patients were subdivided on the basis of whether they received thromboprophylaxis (n = 717,850) or not (n = 1,649,512). The thromboprophylaxis rate was low, despite increasing from 26% to 33% over the study period. Patients receiving thromboprophylaxis had significantly lower risk-adjusted mortality rates than those who did not (p < 0.001), except those with ischemic stroke. The mean total drug cost per patient receiving LMWH and UFH ($791 and $569, respectively) was higher than for patients not receiving thromboprophylaxis ($372) (p < 0.001). The mean total hospital cost per patient receiving UFH ($7615) was higher than for LMWH ($6866, p < 0.001).

CONCLUSION

The thromboprophylaxis rate among medical patients was low, with no significant improvement between 2001 and 2004. Thromboprophylaxis can impact patient mortality rates. Economic evaluation revealed that the use of LMWH for thromboprophylaxis in at-risk medical patients was associated with higher total drug costs but lower total hospital costs than UFH. Efforts should be made to increase clinicians' awareness of clinical guidelines.

Selective cleavage of heparin using aqueous 2-hydroxypyridine: Production of an aldose-terminating fragment with high anticoagulant activity

Unfractionated heparin (UFH) was partially depolymerized by heating at 115 degrees C with aqueous 2-hydroxypyridine. Compared to starting UFH, no significant loss of anticoagulant (anti-Xa) activity was observed. Products consisted of polysaccharide fragments and small quantities of ammonia, sulfate, and hexuronic acid. Fragments with aldose termini that reacted with [3H]NaBH4 (fragment A) were of relatively uniform size (6000 D) and increased as depolymerization time increased. Fragment A contained the anticoagulant activity, with 90-94% and 24-31% binding to Sepharose-thrombin and Sepharose-antithrombin, respectively. In contrast, a non-reducing fragment B that did not react with [3H]NaBH4 was more heterogeneous (6000-10,000 D) and did not have anticoagulant activity or Sepharose-antithrombin affinity. Given the polysaccharide 3H-incorporation, small release of monosaccharide products, and fragment A end-group analysis, thermolysis of UFH is likely limited to one site per molecule when protected by 2-hydroxypyridine. Thus, an anticoagulant fragment A is hydrolytically released from UFH leaving a variable-length fragment B complete with linkage region.

Counteracting venous stasis during acute lower leg immobilization

AIM

During lower limb immobilization, patients are at risk to develop deep venous thrombosis. Recently, a water-pad was developed that should counteract venous stasis. The water-pad, located under the plaster, mobilizes water from the foot to the calf during weight bearing and, thereby, imitates muscle pump function. The purpose of this study was to assess the effect of the water-pad on venous pump function in healthy individuals.

METHODS

In 21 healthy subjects (10 men and 11 women) both legs were plastered. Venous pump function was assessed by plethysmography measuring lower leg venous ejection fraction and volume. Subjects were tilted from the supine position to upright standing to determine total venous volume. Hereafter, stepping was performed to measure venous ejection fraction and volume under different filling conditions of the water-pad (0, 50, 100, 150, 200, 250 and 300 mL). Different sizes of water-pads (small, medium and large) were applied to each plastered leg in order to test the effectiveness and to relate optimum size to anthropometrical data.

RESULTS

The venous ejection fraction increased significantly from 30 +/- 17% to a maximum of 42 +/- 19% during stepping with increasing filling condition (RM anova; P = 0.009). Ejection volume also enhanced significantly during stepping with increasing filling condition from 1.3 +/- 0.7 to 1.9 +/- 0.9 mL (100 mL)(-1) (RM ANOVA; P = 0.006). The optimal filling condition of the water-pad depended on the water-pad size, while body height was the best predictive value for the water-pad size (Pearson's R = 0.72, P < 0.001).

CONCLUSION

The filled water-pad markedly increased the venous ejection fraction and volume of the lower leg during stepping, hereby counteracting stasis of venous blood in the immobilized lower leg. Therefore, the water-pad seems to be a promising tool to prevent deep venous thrombosis during periods of lower leg immobilization.