Prolonged prophylaxis with unfractioned heparin is effective to reduce delayed deep vein thrombosis in total hip replacement

American Society of Hematology 2019 guidelines for management of venous thromboembolism: prevention of venous thromboembolism in surgical hospitalized patients

BACKGROUND

Venous thromboembolism (VTE) is a common source of perioperative morbidity and mortality.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support decision making about preventing VTE in patients undergoing surgery.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline-development process, including performing systematic reviews. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 30 recommendations, including for major surgery in general (n = 8), orthopedic surgery (n = 7), major general surgery (n = 3), major neurosurgical procedures (n = 2), urological surgery (n = 4), cardiac surgery and major vascular surgery (n = 2), major trauma (n = 2), and major gynecological surgery (n = 2).

CONCLUSIONS

For patients undergoing major surgery in general, the panel made conditional recommendations for mechanical prophylaxis over no prophylaxis, for pneumatic compression prophylaxis over graduated compression stockings, and against inferior vena cava filters. In patients undergoing total hip or total knee arthroplasty, conditional recommendations included using either aspirin or anticoagulants, as well as for a direct oral anticoagulant over low-molecular-weight heparin (LMWH). For major general surgery, the panel suggested pharmacological prophylaxis over no prophylaxis, using LMWH or unfractionated heparin. For major neurosurgery, transurethral resection of the prostate, or radical prostatectomy, the panel suggested against pharmacological prophylaxis. For major trauma surgery or major gynecological surgery, the panel suggested pharmacological prophylaxis over no prophylaxis.

Venous Thromboembolism Prophylaxis Strategies for People Undergoing Elective Total Hip Replacement: A Systematic Review and Network Meta-Analysis

OBJECTIVES

To assess the efficacy and safety of venous thromboembolism prophylaxis in people undergoing elective total hip replacement.

METHODS

Systematic review and Bayesian network meta-analyses of randomized controlled trials were conducted for 3 outcomes: deep vein thrombosis (DVT), pulmonary embolism (PE), and major bleeding (MB). MEDLINE, EMBASE, and Cochrane Library (CENTRAL) databases were searched. Study quality was assessed using the Cochrane risk-of-bias checklist. Fixed- and random-effects models were fitted and compared. The median relative risk (RR) and odds ratio (OR) compared with no prophylaxis, with their 95% credible intervals (CrIs), rank, and probability of being the best, were calculated.

RESULTS

Forty-two (n = 24 374, 26 interventions), 30 (n = 28 842, 23 interventions), and 24 (n = 31 792, 15 interventions) randomized controlled trials were included in the DVT, PE, and MB networks, respectively. Rivaroxaban had the highest probability of being the most effective intervention for DVT (RR 0.06 [95% CrI 0.01-0.29]). Strategy of low-molecular-weight heparin followed by aspirin had the highest probability of reducing the risk of PE and MB (RR 0.0011 [95% CrI 0.00-0.096] and OR 0.37 [95% CrI 0.00-26.96], respectively). The ranking of efficacy estimates across the 3 networks, particularly PE and MB, had very wide CrIs, indicating high degree of uncertainty.

CONCLUSIONS

A strategy of low-molecular-weight heparin given for 10 days followed by aspirin for 28 days had the best benefit-risk balance, with the highest probability of being the best on the basis of the results of the PE and MB network meta-analyses. Nevertheless, there is considerable uncertainty around the median ranks of the interventions.

The effectiveness of graduated compression stockings for prevention of venous thromboembolism in orthopedic and abdominal surgery patients requiring extended pharmacologic thromboprophylaxis

OBJECTIVE

There is an increasing evidence base to support the use of extended pharmacologic thromboprophylaxis in selected surgical patients to prevent venous thromboembolism (VTE). The benefit of graduated compression stockings (GCS) in addition to extended pharmacologic thromboprophylaxis is unclear. The aim of this study was to systematically review the evidence relating to the effectiveness of using GCS in conjunction with extended pharmacologic thromboprophylaxis to prevent VTE in surgical patients.

METHODS

A literature search of MEDLINE, Embase, Cochrane Library, and ClinicalTrials.gov databases was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in April 2017. The review protocol was published on PROSPERO (CRD42017062655). Randomized controlled trials (RCTs) were eligible if one of the study arms included patients receiving extended pharmacologic thromboprophylaxis alone (>21 days) or in conjunction with GCS. Data on deep venous thrombosis (DVT), pulmonary embolism (PE), and VTE-related death were compiled. Pooled proportions of the VTE rates were determined using random-effects meta-analysis.

RESULTS

The systematic search identified 1291 studies, of which 19 studies were eligible for inclusion. No RCT directly compared extended pharmacologic thromboprophylaxis alone with GCS plus extended pharmacologic thromboprophylaxis. A total of 9824 patients from 16 RCTs were treated with extended pharmacologic thromboprophylaxis, of whom 0.81% (95% confidence interval [CI], 0.5-1.20) were diagnosed with symptomatic DVT and 0.2% (95% CI, 0.12-0.36) with PE. Three trials included 337 patients who received extended pharmacologic thromboprophylaxis in conjunction with GCS. In this group, 1.61% (95% CI, 0.03-5.43) had symptomatic DVT with no reported PE. Similar VTE rates were observed when studies in orthopedic and abdominal surgery were analyzed separately.

CONCLUSIONS

There is insufficient evidence to recommend GCS in conjunction with extended pharmacologic prophylaxis to prevent VTE in patients undergoing orthopedic and abdominal surgery. A clinical trial directly investigating this important subject is needed.

Anticoagulants (extended duration) for prevention of venous thromboembolism following total hip or knee replacement or hip fracture repair

BACKGROUND

The optimal duration of thromboprophylaxis after total hip or knee replacement, or hip fracture repair remains controversial. It is common practice to administer prophylaxis using low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH) until discharge from hospital, usually seven to 14 days after surgery. International guidelines recommend extending thromboprophylaxis for up to 35 days following major orthopaedic surgery but the recommendation is weak due to moderate quality evidence. In addition, recent oral anticoagulants that exert effect by direct inhibition of thrombin or activated factor X lack the need for monitoring and have few known drug interactions. Interest in this topic remains high.

OBJECTIVES

To assess the effects of extended-duration anticoagulant thromboprophylaxis for the prevention of venous thromboembolism (VTE) in people undergoing elective hip or knee replacement surgery, or hip fracture repair.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Specialised Register (last searched May 2015) and CENTRAL (2015, Issue 4). Clinical trials databases were searched for ongoing or unpublished studies.

SELECTION CRITERIA

Randomised controlled trials assessing extended-duration thromboprophylaxis (five to seven weeks) using accepted prophylactic doses of LMWH, UFH, vitamin K antagonists (VKA) or direct oral anticoagulants (DOAC) compared with short-duration thromboprophylaxis (seven to 14 days) followed by placebo, no treatment or similar extended-duration thromboprophylaxis with LMWH, UFH, VKA or DOACs in participants undergoing hip or knee replacement or hip fracture repair.

DATA COLLECTION AND ANALYSIS

We independently selected trials and extracted data. Disagreements were resolved by discussion. We performed fixed-effect model meta-analyses with odds ratios (ORs) and 95% confidence intervals (CIs). We used a random-effects model when there was heterogeneity.

MAIN RESULTS

We included 16 studies (24,930 participants); six compared heparin with placebo, one compared VKA with placebo, two compared DOAC with placebo, one compared VKA with heparin, five compared DOAC with heparin and one compared anticoagulants chosen at investigators' discretion with placebo. Three trials included participants undergoing knee replacement. No studies assessed hip fracture repair.Trials were generally of good methodological quality. The main reason for unclear risk of bias was insufficient reporting. The quality of evidence according to GRADE was generally moderate, as some comparisons included a single study, low number of events or heterogeneity between studies leading to wide CIs.We showed no difference between extended-duration heparin and placebo in symptomatic VTE (OR 0.59, 95% CI 0.35 to 1.01; 2329 participants; 5 studies; high quality evidence), symptomatic deep vein thrombosis (DVT) (OR 0.73, 95% CI 0.39 to 1.38; 2019 participants; 4 studies; moderate quality evidence), symptomatic pulmonary embolism (PE) (OR 0.61, 95% CI 0.16 to 2.33; 1595 participants; 3 studies; low quality evidence) and major bleeding (OR 0.59, 95% CI 0.14 to 2.46; 2500 participants; 5 studies; moderate quality evidence). Minor bleeding was increased in the heparin group (OR 2.01, 95% CI 1.43 to 2.81; 2500 participants; 5 studies; high quality evidence). Clinically relevant non-major bleeding was not reported.We showed no difference between extended-duration VKA and placebo (one study, 360 participants) for symptomatic VTE (OR 0.10, 95% CI 0.01 to 1.94; moderate quality evidence), symptomatic DVT (OR 0.13, 95% CI 0.01 to 2.62; moderate quality evidence), symptomatic PE (OR 0.32, 95% CI 0.01 to 7.84; moderate quality evidence) and major bleeding (OR 2.89, 95% CI 0.12 to 71.31; low quality evidence). Clinically relevant non-major bleeding and minor bleeding were not reported.Extended-duration DOAC showed reduced symptomatic VTE (OR 0.20, 95% CI 0.06 to 0.68; 2419 participants; 1 study; moderate quality evidence) and symptomatic DVT (OR 0.18, 95% CI 0.04 to 0.81; 2459 participants; 2 studies; high quality evidence) compared to placebo. No differences were found for symptomatic PE (OR 0.25, 95% CI 0.03 to 2.25; 1733 participants; 1 study; low quality evidence), major bleeding (OR 1.00, 95% CI 0.06 to 16.02; 2457 participants; 1 study; low quality evidence), clinically relevant non-major bleeding (OR 1.22, 95% CI 0.76 to 1.95; 2457 participants; 1 study; moderate quality evidence) and minor bleeding (OR 1.18, 95% CI 0.74 to 1.88; 2457 participants; 1 study; moderate quality evidence).We showed no difference between extended-duration anticoagulants chosen at investigators' discretion and placebo (one study, 557 participants, low quality evidence) for symptomatic VTE (OR 0.50, 95% CI 0.09 to 2.74), symptomatic DVT (OR 0.33, 95% CI 0.03 to 3.21), symptomatic PE (OR 1.00, 95% CI 0.06 to 16.13), and major bleeding (OR 5.05, 95% CI 0.24 to 105.76). Clinically relevant non-major bleeding and minor bleeding were not reported.We showed no difference between extended-duration VKA and heparin (one study, low quality evidence) for symptomatic VTE (OR 1.64, 95% CI 0.85 to 3.16; 1279 participants), symptomatic DVT (OR 1.36, 95% CI 0.69 to 2.68; 1279 participants), symptomatic PE (OR 9.16, 95% CI 0.49 to 170.42; 1279 participants), major bleeding (OR 3.87, 95% CI 1.91 to 7.85; 1272 participants) and minor bleeding (OR 1.33, 95% CI 0.64 to 2.76; 1279 participants). Clinically relevant non-major bleeding was not reported.We showed no difference between extended-duration DOAC and heparin for symptomatic VTE (OR 0.70, 95% CI 0.28 to 1.70; 15,977 participants; 5 studies; low quality evidence), symptomatic DVT (OR 0.60, 95% CI 0.11 to 3.27; 15,977 participants; 5 studies; low quality evidence), symptomatic PE (OR 0.91, 95% CI 0.43 to 1.94; 14,731 participants; 5 studies; moderate quality evidence), major bleeding (OR 1.11, 95% CI 0.79 to 1.54; 16,199 participants; 5 studies; high quality evidence), clinically relevant non-major bleeding (OR 1.08, 95% CI 0.90 to 1.28; 15,241 participants; 4 studies; high quality evidence) and minor bleeding (OR 0.95, 95% CI 0.82 to 1.10; 11,766 participants; 4 studies; high quality evidence).

AUTHORS' CONCLUSIONS

Moderate quality evidence suggests extended-duration anticoagulants to prevent VTE should be considered for people undergoing hip replacement surgery, although the benefit should be weighed against the increased risk of minor bleeding. Further studies are needed to better understand the association between VTE and extended-duration oral anticoagulants in relation to knee replacement and hip fracture repair, as well as outcomes such as distal and proximal DVT, reoperation, wound infection and healing.

Impact of screening versus symptomatic measurement of deep vein thrombosis in a national quality improvement registry

BACKGROUND

Deep vein thrombosis (DVT) is a quality measure recorded by initiatives such as the National Surgical Quality Improvement Program (NSQIP). However, because surveillance-detected DVT rates may be higher than symptomatic DVT rates, we examined how differences in the method of DVT detection may affect the use of this quality measure.

METHODS

Using the NSQIP database (2007-2009), we compared DVT rates of vascular (amputation, open aortic procedures, and lower extremity bypass) and nonvascular (prostatectomy, gastric bypass [GBP], and hip arthroplasty) operations. Using a predefined literature search strategy, we compared the incidence of DVT in NSQIP to the incidence of DVT reported in published literature, diagnosed by symptomatic status or by surveillance studies.

RESULTS

Within NSQIP, the overall incidence of postoperative DVT was 0.7%. This varied from 0.3% after GBP to 1.8% after open aortic surgery. Across all procedures except amputation, the incidence of DVT in NSQIP was similar to the incidence of DVT reported in our literature survey of "symptomatic" DVTs. The relative rate (RR) of literature-derived symptomatic DVTs to NSQIP ranged from 0.7 for aortic cases (95% confidence interval [CI], 0.3-1.7) to 1.4 (95% CI, .7-3.1) for GBP. Overall, surveillance studies had 11.6 higher RR of DVT compared to NSQIP (95% CI, 10.5-13), ranging from 2.6 for GBP (95% CI, 1.4-5) to 14 .5 for hip arthroplasty (95% CI, 10.5-20).

CONCLUSIONS

The incidence of DVT reported in NSQIP is similar to the reported incidence of symptomatic DVT for many high-risk procedures but is much lower than rates of DVT reported in surveillance studies. Clear delineation of symptomatic vs surveillance detection of DVT would improve the usefulness of this measurement in quality improvement registries.

An obscure case of hepatic subcapsular hematoma

Spontaneous liver bleeding is often reported in preeclampsia. It is otherwise rare and has been linked to gross anatomical lesions and coagulopathy. We report a case of subcapsular hematoma of the liver without any apparent lesion and in the absence of coagulopathy. A 41-year-old male, paraplegic for 16 years, presented to the emergency department 3 days after sudden onset of right upper quadrant and shoulder pain. He had been on vitamins and 5,000 units subcutaneous heparin 12-hourly at the nursing home for the last month. He was in no distress, afebrile, with stable vitals. Physical examination showed a diverting colostomy, tender hepatomegaly and sacral decubiti. A fecal occult blood test was negative. There was spastic paraplegia below the level of T12. Two days after admission, the patient was afebrile and hemodynamically stable. PTT, PT, liver profile, BUN and creatinine were all normal, however his hemoglobin had dropped from 11.3 to 7.6 g/dl. An abdominal CT scan revealed an isolated 9.0 × 1.8 cm subcapsular hematoma. The patient received blood transfusion in the intensive care unit and was discharged 7 days later. In conclusion, spontaneous liver hemorrhage occurs in the nonobstetrical population in the setting of gross anatomical lesions or coagulopathy. This is the first report of an isolated subcapsular liver hematoma.

Cost-effectiveness of prolonged thromboprophylaxis after cancer surgery

BACKGROUND

Consensus guidelines recommend prolonged thromboprophylaxis for up to 4 weeks after major abdominopelvic cancer operations. Several factors impede widespread adoption of these guidelines. These include lack of awareness, cost, increased bleeding complications, increased incidence of heparin-induced thrombocytopenia, and poor patient compliance.

METHODS

A cost-effectiveness model was constructed comparing four potential strategies to postdischarge thromboprophylaxis in surgical oncology patients: (1) low-molecular-weight heparin (LMWH) once daily; (2) low-dose unfractionated heparin (LDUH) three times daily; (3) oral aspirin once daily; or (4) no prolonged prophylaxis. Probabilities and costs were estimated on the basis of published literature and average Medicare reimbursement. The decision analysis was conducted from the perspective of the health care system, with the primary end point being cost per patient without venous thromboembolism (VTE). Sensitivity analyses tested the robustness of the results.

RESULTS

LDUH was most cost-effective, saving $154 per patient without VTE compared with no prophylaxis. LMWH was not cost-effective, incurring a cost of $230 per patient without VTE compared with no prophylaxis. Aspirin was a viable alternative to LDUH, saving $123 compared with no prophylaxis. When poor compliance was considered, aspirin became the dominant strategy. Sensitivity analyses failed to show any instance where LMWH was cost-effective. In terms of population costs, widespread use of LDUH after discharge would save $30.3 million per year in the United States.

CONCLUSIONS

Although all chemical prophylaxis is effective in preventing VTE in the outpatient setting after cancer surgery, either LDUH or aspirin are the most cost-effective, depending on patient compliance.

Cost-effectiveness of extended prophylaxis with fondaparinux compared with low molecular weight heparin against venous thromboembolism in patients undergoing hip fracture surgery

A model was developed to estimate costs and clinical effectiveness of fondaparinux compared with enoxaparin after hip fracture surgery in Sweden. Outcomes and costs of venous thromboembolism (VTE)-related care from a health care perspective were incorporated, with symptomatic deep-vein thrombosis and pulmonary embolism, recurrent VTE, post-thrombotic syndrome, major haemorrhage and all-cause death being included. Event probabilities were derived from fondaparinux clinical trial data and published data. VTE-related resource use and associated costs as well as costs of prophylaxis were based on local Swedish data. Extended prophylaxis with fondaparinux could avoid an additional 28 symptomatic VTE per 1,000 patients compared with extended prophylaxis with enoxaparin in hip fracture surgery patients. Although the prophylaxis costs were higher in the fondaparinux group, these were offset by the lower costs associated with treating fewer VTE, which thus indicates that extended fondaparinux prophylaxis is the dominant alternative when compared with enoxaparin in hip fracture surgery.

A review of the risks and benefits of differing prophylaxis regimens for the treatment of deep venous thrombosis and pulmonary embolism in neurosurgery

BACKGROUND

Annually, 2 million people in the United States develop deep venous thrombosis (DVT), and nearly 100,000 sustain fatal pulmonary emboli. Prophylaxis against DVT/pulmonary embolism (PE) is a critical issue, and options include elastic stockings, intermittent pneumatic compression stockings, low-dose unfractionated heparin (5000 U every 8-12 hours), and low molecular-weight heparin (ie, enoxaparin and dalteparin). The risks and benefits associated with different prophylaxis regimens used in the prevention of DVT and PE in neurosurgical procedures were analyzed.

METHODS

Neurosurgical studies focusing on different methods of prophylaxis used for the prevention of DVT and PE were reviewed. The efficacy, risks, and benefits of varied treatment options were evaluated, with particular emphasis on minor and major hemorrhages occurring where heparin-based protocols were used.

RESULTS

In Flinn et al series (Arch Surg. 1996;131(5):472-80), the incidence of DVT was greater for cranial (7.7%) than spinal procedures (1.5%). Although intermittent pneumatic compression devices provided adequate reduction of DVT/PE in some cranial and combined cranial/spinal series, low-dose subcutaneous unfractionated heparin or low molecular-weight heparins further reduced the incidence, not always of DVT, but of PE (Br J Neurosurg 1995;9(2):159-63; J Intensive Care Med 2003;18(2):59-79). Nevertheless, low-dose heparin-based prophylaxis in cranial and spinal series risks minor and major postoperative hemorrhages: 2% to 4% in a cranial series, 3.4% minor and 3.4% major hemorrhages in a combined cranial/spinal series, and a 0.7% incidence of major/minor hemorrhages in a spinal series (J Neurosurg 2003;99(4):680-4; Neurosurgery 1986;18(4):440-5; Eur Spine J 2004;13(1):1-8; J Intensive Care Med 2003;18(2):59-79).

CONCLUSIONS

Although mechanical prophylaxis provided effective prophylaxis against DVT/PE in many series, the added efficacy of low-dose heparin regimens has to be weighed against risks of major postoperative hemorrhages and their neurological sequelae.

Intermittent pneumatic compression stocking prophylaxis against deep venous thrombosis in anterior cervical spinal surgery: a prospective efficacy study in 200 patients and literature review

STUDY DESIGN

Intermittent pneumatic compression stockings (IPC) alone were prospectively used to avoid deep venous thrombosis (DVT) and pulmonary embolism (PE) in 100 consecutive patients undergoing single-level anterior corpectomy/fusion (ACF) and in 100 patients having multilevel ACF/posterior fusion.

OBJECTIVES

To determine the optimal prophylaxis against DVT and PE for patients undergoing anterior cervical spinal surgery.

BACKGROUND DATA

Mini-heparin and low-dose heparin prophylaxis in neurosurgery poses a 2% to 4% risk of major postoperative hemorrhage with resultant neurologic sequelae.

METHODS

Prophylaxis consisted of IPC alone. Doppler studies of the lower extremities were routinely obtained 2 days after surgery. Single-level ACF (100 patients) addressed two-level disc disease, spondylostenosis, and ossification of the posterior longitudinal ligament (OPLL). One hundred patients undergoing multilevel ACF (3+ levels) with posterior fusion (C2-T1) exhibited OPLL/spondylostenosis.

RESULTS

One patient undergoing single-level ACF developed DVT/PE 6 days after surgery; she exhibited Factor V Leiden mutation (hypercoagulability syndrome). Although 7 patients undergoing circumferential surgery developed DVT 2 to 14 days following surgery (mean, 7.15 days), only two clots localized in the iliac veins resulted in PEs (days 10 and 14 after surgery).

CONCLUSIONS

IPCs were as effective for prophylaxis against DVT/PE for 100 patients undergoing single-level ACF and for 100 having circumferential procedures as existing therapies (mini-heparin and low-dose heparin), without the risk of hemorrhage. However, the 1% and 2% respective rates of PE were comparable to frequencies of PE encountered in other cranial/spinal series using mini-heparin and/or low-dose heparin regimens but avoided the 2% to 4% risk of major postoperative hemorrhage.

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

Objectives: The frequency and consequences of major bleeding associated with anticoagulant prophylaxis for prevention of venous thromboembolism is examined.

Methods: We conducted a systematic review and meta-analysis of controlled trials that reported rates of major bleeding after pharmaceutical thromboprophylaxis in patients undergoing major orthopedic surgery. Thromboprophylactic agents were divided into four groups:warfarin/other coumarin derivatives (WARF), unfractionated heparin (UFH), low molecular weight heparin (LMWH), and pentasaccharide (PS). Meta-analysis was conducted comparing LMWH with each of WARF, UFH, and PS. The frequency of re-operation due to major bleeding was reviewed and combined with published costs to estimate the mean cost of managing major bleeding events in these patients.

Results: Twenty-one studies including 20,523 patients met inclusion criteria for the meta-analysis. No evidence of significant between-trial heterogeneity in risk ratios was found. Combined (fixed effects) relative risks (RR) of major bleeding compared with LMWH were WARF – RR 0.59 (95 percent confidence interval [CI], 0.44–0.80); UFH – RR 1.52 (95 percent CI, 1.04–2.23); PS – RR 1.52 (95 percent CI, 1.11–2.09). Seventy-one studies including 32,433 patients were included in the review of consequences of major bleeding. We estimated that the average cost of major bleeding is $113 per patient receiving thromboprophylaxis.

Conclusions: LMWH results in fewer major bleeding episodes than UFH and PS but more than WARF. These events are costly and clinically important.

Evidence for Extended Prophylaxis in the Setting of Orthopedic Surgery

Patients undergoing orthopedic surgery represent one of the highest risk groups for the development of venous thromboembolism (VTE). Evidence shows that this risk extends beyond the period in which the patient is hospitalized, especially for patients undergoing hip surgery. Clinical trials have shown that extended prophylaxis with the low-molecular-weight heparins is effective in reducing the rate of total VTE, and a meta-analysis demonstrated a reduction in symptomatic VTE with extended prophylaxis after total hip replacement surgery. Based on these results, the American College of Chest Physicians gives a grade 2A recommendation for the use of extended prophylaxis after orthopedic surgery. Until recently, data evaluating the role of prophylaxis in patients undergoing hip fracture surgery were limited. Subsequently, a novel anticoagulant, fondaparinux, demonstrated significant benefit in these patients and has become the first and only agent approved by the United States Food and Drug Administration (FDA) for use in patients undergoing hip fracture surgery Despite the limitations of the older trials, their findings supported the need to evaluate extended prophylaxis in patients undergoing hip fracture surgery. In the first well-conducted trial of extended prophylaxis for hip fracture surgery, fondaparinux provided impressive results in reducing total and symptomatic VTE. The results of this trial have once again led to fondaparinux being the first and only agent to be granted FDA approval for the indication of extended prophylaxis in patients undergoing hip fracture surgery.

Duration of Venous Thromboembolism Prophylaxis After Surgery

Venous thromboembolism (VTE) prophylaxis is indicated while in the hospital after major surgery. There is evidence that the prevalence of asymptomatic deep-vein thrombosis, detected by routine venography after major orthopedic surgery, is lower at hospital discharge in patients who have received 10 days rather than 5 days of prophylaxis. This observation supports the current American College of Chest Physicians (ACCP) recommendation for a minimum of 7 to 10 days of prophylaxis after hip and knee replacement, even if patients are discharged from the hospital within 7 days of surgery. As risk of VTE persists for up to 3 months after surgery, patients at high risk for postoperative VTE may benefit from extended prophylaxis (eg, an additional 3 weeks after the first 7 to 10 days). Extended prophylaxis with low-molecular-weight heparin (LMWH) reduces the frequency of postdischarge VTE by approximately two thirds after hip replacement; however, the resultant absolute reduction in the frequency of fatal pulmonary embolism is small (ie, estimated at 1 per 2,500 patients). Indirect evidence suggests that, compared with LMWH, efficacy of extended prophylaxis after hip replacement is greater with fondaparinux, similar with warfarin, and less with aspirin. Extended prophylaxis is expected to be of less benefit after knee than after hip replacement. In keeping with current ACCP recommendations, at a minimum, extended prophylaxis should be used after major orthopedic surgery in patients who have additional risk factors for VTE (eg, previous VTE, cancer). If anticoagulant drug therapy is stopped after 7 to 10 days, an additional month of prophylaxis with aspirin should be considered.

Extended thromboprophylaxis after hip or knee replacement

Early discharge from the hospital after total joint arthroplasty has increased the need for extended outpatient thromboprophylaxis. Multiple controlled clinical trials and several meta-analyses of these data have examined various agents in different regimens. These data indicate that extended prophylaxis with a low-molecular-weight heparin after knee or hip arthroplasty significantly reduces the number of venous thromboembolic episodes with no increases in major bleeding. The data also show that > 98% of patients given long-term low-molecular-weight heparin prophylaxis remain free from symptomatic deep venous thrombosis and pulmonary embolism. Therefore, to minimize patient risk safely and cost-effectively, extended prophylaxis with low-molecular-weight heparin once-daily for 4 weeks after surgery should be considered for patients undergoing total joint arthroplasty.

Critical appraisal of current antithrombotic trials in patients undergoing total hip replacement

Patients undergoing total hip replacement are at high risk of developing venous thromboembolism. The 6th ACCP Consensus Conference on Antithrombotic Therapy identified two effective prophylactic methods; low molecular weight heparins (LMWH) and oral anticoagulants. However, two key issues remain controversial. The relative efficacy and safety of prophylaxis initiated pre operatively and post operatively and the optimum duration of prophylaxis. Clinical practice has diverged in North America and Europe as to the appropriate time to administer prophylaxis. This treatment is given pre-operatively in Europe and post-operatively in North America. A number of recent studies have demonstrated that an effective antithrombotic agent administered either immediately before or after surgery may be more effective than current practice. The use of LMWH for extended thromboprophylaxis is supported by convincing data. Clinical trials have demonstrated a significant benefit of pentasaccharide in the prevention of venous thromboembolism in major orthopaedic surgery. A direct thrombin inhibitor given sc. followed by oral administration was found to be as effective and safe as LMWH for the prophylaxis of deep vein thrombosis (DVT) following major hip or knee surgery.

Extended-duration prophylaxis against venous thromboembolism after total hip or knee replacement: a meta-analysis of the randomised trials

BACKGROUND

The optimum duration of prophylaxis against venous thromboembolism after total hip or knee replacement is uncertain. Our primary objective was to establish the efficacy of extended-duration prophylaxis on symptomatic venous thromboembolic events.

METHODS

We identified randomised trials comparing extended-duration prophylaxis using heparin or warfarin with placebo or untreated control in patients undergoing elective total hip or knee replacement by searching electronic databases (MEDLINE, EMBASE), references from retrieved articles, and abstracts from conference proceedings, and by contact with pharmaceutical companies and investigators. Two reviewers independently extracted data on study design, symptomatic and symptomless venographic venous thromboembolism, death, and bleeding outcomes. Results from individual trials were combined with the Mantel-Haenszel method.

FINDINGS

Nine studies met our inclusion criteria (3999 patients), eight with low molecular weight heparin, and one with unfractionated heparin. Extended-duration prophylaxis for 30-42 days significantly reduced the frequency of symptomatic venous thromboembolism (1.3% vs 3.3%, OR 0.38; 95% CI 0.24-0.61, numbers needed to treat [NNT]=50), with no statistical evidence of heterogeneity (x(2) test, p=0.69). There was a greater risk reduction in patients undergoing hip replacement (1.4% vs 4.3%, 0.33; 0.19-0.56, 34) compared with knee replacement (1.0% vs 1.4%, 0.74; 0.26-2.15, 250). A significant reduction in symptomless venographic deep vein thrombosis was also observed (9.6% vs 19.6%, 0.48; 0.36-0.63, 10). There was no increase in major bleeding but extended-duration prophylaxis was associated with excess minor bleeding (3.7% vs 2.5%, 1.56; 1.08-2.26, numbers needed to harm [NNH]=83).

INTERPRETATION

Among patients undergoing total hip or knee replacement, extended-duration prophylaxis significantly reduces the frequency of symptomatic venous thromboembolism. The reduction in risk is equivalent to about 20 symptomatic events per 1000 patients treated.