Optimal duration of prophylaxis for venous thromboembolism following total hip arthroplasty and total knee arthroplasty

Incidence of in-hospital and post-discharge diagnosed hospital-associated venous thromboembolism using linked administrative data

BACKGROUND

Hospital-associated venous thromboembolism (HA-VTE) is a serious adverse event, preventable with appropriate care during and post-admission. Accurate measurement of in-hospital and post-discharge incidences is essential for implementation and evaluation of prevention strategies and monitoring.

AIMS

To estimate in-hospital and post-discharge diagnosed VTE, trends and risk factors.

METHODS

This was a population-based study in New South Wales, Australia, using linked hospital admission and emergency department data for 2010-2013 of adult patients with a minimum stay of 48 h. HA-VTE were diagnosed in-hospital or post-discharge (within 90 days). Multi-level modelling schemes produced adjusted rates and ratios for patient, admission and hospital-related characteristics.

RESULTS

From 1 865 059 admissions, the HA-VTE incidence rate was 9.7 per 1000 admissions; 71% were diagnosed post-discharge, and 4.3% died with a greater risk for VTE diagnosed in hospital compared to post-discharge (8.4% vs 2.6%, P < 0.001). Compared with surgical patients, medical patients developed fewer HA-VTE (IRR = 0.60, 95% CI: 0.58-0.63) but were more likely to be diagnosed post-discharge (OR = 2.19; 95% CI: 2.00-2.40). HA-VTE increased 6.5% over the period, driven by the 44% increase in in-hospital diagnoses and not by the 9% decrease in post-discharge diagnoses.

CONCLUSIONS

HA-VTE is a continuing burden, and diagnosis after recent hospital discharge is notably high. Incidence varies across patients and facilities, highlighting the need for individual VTE risk assessment. Inclusive measures and routine monitoring of HA-VTE incidence and mortality are essential for implementing best practice and assessing effectiveness of prevention strategies.

Correlation of the Caprini Score and Venous Thromboembolism Incidence Following Primary Total Joint Arthroplasty-Results of a Single-Institution Protocol

BACKGROUND

Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep vein thrombosis, is a serious complication after total joint arthroplasty (TJA). Risk assessment models are increasingly used to provide patient-specific risk stratification. A recently implemented protocol mandates calculation of a Caprini Score for all surgical patients at our institution. We investigated the accuracy of the Caprini Score in predicting VTE events following TJA.

METHODS

A retrospective review of patients undergoing primary total hip (THA) and total knee arthroplasty (TKA) over a 1-year time period was performed. The 90-day postoperative incidence of emergency department evaluations, hospital readmissions, medical complications, need for revision surgery, and symptomatic VTE was recorded. "Preoperative" Caprini Scores routinely recorded per protocol and calculated during review ("Calculated") were compared and assessed for relationship with VTE events. A "VTEstimator" Score was calculated for each patient.

RESULTS

Three hundred seventy-six arthroplasties (151 TKA and 225 THA) meeting inclusion criteria were identified. Ten patients (2.5%) had symptomatic VTE postoperatively, with 3 pulmonary embolism (0.8%) and 7 deep vein thrombosis (1.8%). Eight VTE (5.3%) occurred following TKA and 2 (0.9%) occurred following THA. For each surgical characteristic evaluated, no significant difference was observed between mean Preoperative or Calculated Caprini Scores for patients with and without VTE (P > .05). Additionally, the distribution of VTEstimator Scores for patients with and without VTE was not significantly different (P = .93).

CONCLUSION

The Caprini risk assessment model does not appear to provide clinically useful risk stratification for TJA patients. Alternative risk stratification protocols may provide assistance in balancing safety and efficacy of thromboprophylaxis.

Dosing of rivaroxaban by indication: getting the right dose for the patient

INTRODUCTION

Vitamin K antagonists were the only oral anticoagulants available for several decades, but they require frequent coagulation monitoring and dose adjustment. The direct oral anticoagulants rivaroxaban , dabigatran, apixaban, and, most recently, edoxaban have been approved for the management of specific thromboembolic indications.

AREAS COVERED

This review will provide a brief overview of the cell-based coagulation model, the main determinants of arterial and venous thrombosis, and the pharmacological rationale and clinical evidence for the different dosing regimens of rivaroxaban. Published articles indexed on PubMed and Medline covering arterial and venous thrombi pathophysiology, pharmacokinetics, and pharmacodynamics of rivaroxaban, and Phase II and Phase III clinical studies with rivaroxaban as well as real-world evidence were analyzed.

EXPERT OPINION

Education on pharmacokinetic/pharmacodynamic characteristics, as well as how to manage adverse events, is needed to increase physician knowledge and confidence in using direct oral anticoagulants, as specifically discussed for rivaroxaban in this article. The continued uptake of direct oral anticoagulants in clinical practice depends on understanding of the clinical evidence and reassurance provided by emerging real-world data.

Effects of steroids on thrombogenic markers in patients undergoing unilateral total knee arthroplasty: a prospective, double-blind, randomized controlled trial

Venous thromboembolism (VTE) remains an important complication after total knee arthroplasty (TKA). Systemic thrombin generation starts perioperatively. Inflammation, characterized by a rise in interleukin-6 (IL6), initiates the coagulation cascade, but low-dose steroids can reduce post-TKA IL6 levels. This double-blinded, randomized, placebo-controlled study enrolled 30 patients undergoing unilateral TKA to assess the effect of perioperative steroids on serum prothrombin fragment (PF1.2), a marker of thrombin generation, and plasmin-alpha-2-antiplasmin complex (PAP), a marker of fibrinolysis. Study patients received 100 mg of intravenous hydrocortisone 2 h prior to surgery, and controls received normal saline. Blood samples, drawn pre-incision and at 4 h post tourniquet release, were assayed for PF1.2 and PAP. The study group had significantly lower mean PF1.2 at 4 h compared to controls (616 ± 358 pMol/L vs. 936 ± 332 pMol/L, p = 0.037). The mean rise in PF1.2 in the control group was significantly greater compared to the study group (672 ± 173 pMol/L vs. 350 ± 211 pMol/L, p < 0.001). Mean PAP was higher in the study group at 4 h (1639 ± 823 µg/L vs. 1087 ± 536 µg/L), but did not reach statistical significance (p = 0.07). These results may have clinical implications in terms of postoperative VTE risk and management.

Thromboembolic and bleeding outcomes of extended duration low-intensity warfarin following elective total knee arthroplasty

INTRODUCTION

The purpose of this study was to describe the incidence of symptomatic venous thromboembolism (VTE), clinically-relevant bleeding, and death among a real-world population receiving warfarin prophylaxis targeting an international normalized ratio (INR) of 1.5 to 2.5 for four weeks following total knee arthroplasty (TKA).

MATERIALS AND METHODS

This retrospective, observational study included patients receiving warfarin following a TKA between August 1, 2005 and July 31, 2009 identified in the Kaiser Permanente Total Joint Replacement Registry. Patients<18 years, receiving warfarin for another indication, or without continuous KPCO membership during the study period were excluded.

RESULTS

There were 1487 patients with TKA included in the analysis. Mean patient age was 67.7 years and 61.7% were female. The median percent of time in therapeutic INR range during follow-up was 55% (interquartile range=35%-75%). Nineteen cases of symptomatic VTE [1.3%; 95% confidence interval (CI) 0.8%-2.0%] including ten pulmonary emboli (PE) (0.7%) were identified within 90 days of surgery. Clinically-relevant bleeding occurred in 1.7% (95% CI 1.1%-2.5%) of patients during warfarin prophylaxis and there were no deaths within 90 days of surgery.

CONCLUSIONS

The rates of symptomatic VTE and clinically-relevant bleeding following TKA in patients receiving warfarin prophylaxis with a target INR of 1.5 to 2.5 were low. Additional studies should include low-intensity warfarin to identify the regimen that optimally balances risks of bleeding and symptomatic VTE after major orthopedic surgery.

Review article: Venous thromboembolism after total joint replacement

Venous thromboembolism can occur in up to 84% of cases following total joint replacement. It can result in pain, swelling, chronic post-thrombotic syndrome, and pulmonary embolism. Its prevention is vital to the success of the surgery. To achieve a safe and effective prophylaxis, a combination of mechanical and pharmacologic agents should be used. New generation of thromboprophylactic agents target different factors of the coagulation pathway.

Coagulopathies in orthopaedics: links to inflammation and the potential of individualizing treatment strategies

Orthopaedic patients are at risk for developing pathologic imbalances of coagulation factors characterized by phases of both hypocoagulability and hypercoagulability. Complications from "hypocoagulability" include life-threatening hemorrhage, wound hematoma, and poor wound healing. Complications due to "hypercoagulability" include deep venous thrombosis, pulmonary embolus, and disseminated intravascular coagulation. In addition, coagulation imbalance that favors the production of procoagulant factors may lead to excessive inflammation and contribute to systemic inflammatory response syndrome, acute respiratory distress syndrome, multiple organ dysfunction syndrome, and death. Optimally, the goal of individualized treatment of coagulopathies in orthopaedic patients should be to achieve efficient healing while avoiding the morbidities associated with imbalance of coagulation and inflammation. Such individualized and time-sensitive measures of coagulation status require rapid, accurate, qualitative, and quantitative assessment of the critical balance of the coagulation system. Commonly used coagulation tests (prothrombin time and activated partial thromboplastin time) are incapable of determining this balance. An alternative to is to perform thrombin generation assays. The greatest advantage of thrombin generation assays over traditional coagulation tests is their ability to detect hypercoagulability, the balance of procoagulant and anticoagulant factors, and the effect of all pharmaceutical anticoagulants. Further clinical investigations are warranted to develop and refine the thrombin generation assays to help predict clinical complications related to coagulation imbalances. In addition, future testing will help define the prothrombotic period allowing for appropriate initiation and cessation of anticoagulant pharmaceuticals. These subsequent studies have the potential to allow the development of a real-time coagulation monitoring strategy that could have paramount implications in the management of postoperative patients.

Relationship between deep vein thrombosis and pulmonary embolism following THA and TKA

Patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA) are at risk for venous thromboembolisms, including deep vein thrombosis and pulmonary embolism. Most deep vein thromboses are asymptomatic, but they can lead to long-term morbidity to the same extent as symptomatic events. The risk of complications of venous thromboembolisms depends on the location of thrombi; potential long-term complications include recurrent venous thromboembolism, postthrombotic syndrome, and chronic thromboembolic pulmonary hypertension. Risk of recurrence persists for several years after the initial event. Approximately 20% of recurrent events are pulmonary embolisms, and approximately half of those are fatal. The causal relationship between deep vein thrombosis and pulmonary embolism remains controversial. Some consider them distinct clinical entities, while others have found asymptomatic distal deep vein thrombosis to be associated with elevated risk of developing pulmonary embolism. Unique coagulation factors may be associated with orthopedic surgery patients that differentiate them from patients undergoing other types of surgery. Symptomatic and asymptomatic deep vein thrombosis can lead to the development of recurrent venous thromboembolism, pulmonary embolism, postthrombotic syndrome, and chronic thromboembolic pulmonary hypertension, all of which are associated with reduced quality of life and increased health care expenditures. Thromboprophylaxis is therefore important in patients undergoing THA or TKA. However, traditional anticoagulants are not ideal, particularly for long-term use. Orthopedic surgeons should be aware of the causes and potential sequelae of venous thromboembolism and of the new thromboprophylactic agents that can help prevent it.

Micro-mobile foot compression device compared with pneumatic compression device

BACKGROUND

A combination mechanical-pharmacologic regimen is an accepted prophylactic treatment against symptomatic venous thromboembolism for patients undergoing total hip and knee arthroplasties. Foot pumps have been recognized as effective mechanical devices. Research suggests pharmacologic prophylaxis for venous thromboembolism is associated with complications and foot pumps offer an adjunct or alternative approach. Presumably the effectiveness of foot pumps relate to enhancement of venous flow.

QUESTIONS/PURPOSES

We compared an established foot pump system with a new mobile foot pump for their ability to influence mean peak venous velocity in the common femoral, popliteal, and posterior tibial veins.

METHODS

We evaluated 60 healthy subjects with the established and the novel foot-pump systems. Ultrasonography was used to measure baseline and peak venous velocity with mechanical compression. We constructed 95% confidence intervals (CI) on the mean differences between the two devices to establish equivalence limits. We compared ratios of peak velocity to resting velocity. Subjects subjectively rated the two foot pumps with respect to size, fit, and comfort.

RESULTS

The 95% CI test for equivalence of the mean differences between the two devices was inconclusive. The novel device augmented the venous velocity 11 times greater than the resting velocity in the posterior tibial vein and three times greater than the resting velocity in the popliteal vein. The established foot pump augmented the venous velocity 15 times greater than the resting velocity in the posterior tibial vein and four times greater than the resting velocity in the popliteal vein. The novel device rated better for size, fit, and comfort when compared with the established device.

CONCLUSIONS

The established foot pump tended to be associated with greater peak velocities; the novel device produced more consistent mean peak venous velocities and may be more acceptable to patients and caregivers.

Prevention of VTE Following total hip and knee arthroplasty in Hemophilia patients

The often debilitating condition of hemophilic arthropathy is treated with elective total joint arthroplasty. Little has been published addressing the role of thromboembolic prophylaxis in the hemophilic patient population following total hip arthroplasty (THA) and total knee arthroplasty (TKA). Although the American College of Chest Physicians and the American Academy of Orthopaedic Surgeons have set guidelines for thromboembolic prophylaxis in the general population, no such standard of care is in place for hemophilic patients. While the risk of thrombosis in hemophilic patients following THA and TKA is thought to be lower, cases have been reported of pulmonary embolism and deep vein thrombosis (DVT) in hemophilic patients.

Development of consensus guidelines for venous thromboembolism prophylaxis in patients undergoing microvascular reconstruction of the mandible

BACKGROUND

The purpose of this study was to determine how guidelines for venous thromboembolism prophylaxis can be applied to patients undergoing microsurgical reconstruction of the mandible.

METHODS

Retrospective review of our institutional use of thromboprophylaxis and the associated outcomes in 114 patients (58 free fibular flaps and 56 osteocutaneous radial forearm flaps).

RESULTS

Twenty-two patients (19.3%) received only intermittent pneumatic compression. Overall, 80.7% received postoperative chemoprophylaxis. Sixty-four percent initiated chemoprophylaxis within 24 hours after surgery. Only 13.2% received the recommended frequency of chemoprophylaxis. One patient had development of a pulmonary embolism. Four patients undergoing chemoprophylaxis had development of neck hematomas; in each case the cause of bleeding could be attributed to a cause distinct from chemoprophylaxis.

CONCLUSIONS

No consistent chemoprophylaxis protocol was followed. Chemoprophylaxis was not associated with an increased risk of bleeding. Physician education is the next step in decreasing variations in chemoprophylaxis and adopting guidelines similar to The American College of Chest Physicians.

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.

Simplifying thromboprophylaxis could improve outcomes in orthopaedic surgery

Venous thromboembolism is a serious complication after total hip or knee surgery, and there is a well-established clinical need for thromboprophylaxis. However, in a large number of cases adequate administration of thromboprophylaxis does not seem to occur after total joint arthroplasty. A major challenge in the management of thromboprophylaxis is to balance the benefits of treatment with the risks, including bleeding complications. Another potential barrier to the optimal use of thromboprophylaxis could be the inconvenience of currently available agents. Many surgeons therefore adopt a conservative approach towards thromboprophylaxis. Simplifying therapy with more convenient, efficacious, and safe anticoagulants could change attitudes to anticoagulant use and improve adherence to thromboprophylactic guidelines.

Rates of symptomatic venous thromboembolism in US surgical patients: a retrospective administrative database study

US national performance measures may reduce the burden of venous thromboembolism (VTE) in surgical patients. To characterize the VTE rate in US surgical patients, and identify real-world independent VTE risk-factors, a national managed-care database was analyzed. 172,320 eligible surgical discharges (23.9% orthopedic, 76.1% abdominal surgery) from the PharMetrics database (January 2001-December 2005) were evaluated. The rate of thromboprophylaxis was low in orthopedic (40.5%) and abdominal (1.8%) surgery discharges, with the event rates of symptomatic VTE in these groups being 4.7% and 3.1%, respectively. The median time to VTE was 51 days: the majority of VTE events occurred post-discharge. Independent predictors of VTE included prior VTE (odds ratio [OR] 10.2; 95% CI: 9.2-11.4), and orthopedic versus abdominal surgery (OR 1.4; 95% CI: 1.4-1.6). Patients undergoing orthopedic or abdominal surgery remain at-risk for VTE. Implementation of national performance measures may help reduce the burden of VTE.

Review article: thromboprophylaxis after total hip replacement

The risk of secondary haematologic complications such as deep vein thrombosis or pulmonary embolism increases significantly when a transient period of hypercoagulability is induced after total hip replacement (THR). A number of drug-based anticoagulant approaches are available to modulate this risk, but the optimal length of therapy for such approaches remains unclear. The literature was reviewed for evidence-based support of the routine use of an extended course (>14 days) of thromboprophylaxis after THR. Electronic databases and real-time online literature searches were performed, using the PubMed (Medline), EMBASE, CINAHL and GoogleScholar, and the Cochrane and British Medical Journal Clinical Evidence libraries. Author-defined key word searches were performed. Only articles in the English language, for which full text could be retrieved, were reviewed. There is robust evidence to support an extended course (>14 days) of thromboprophylaxis after THR. Such recommendations have been translated into the guidelines of key professional bodies, including those of the American College of Chest Physicians. Meta-review suggests a clear benefit of such regimens and supports wider adoption, even when weighed against a small increase in adverse events.

VKORC1 variant genotypes influence warfarin response in patients undergoing total joint arthroplasty: a pilot study

Warfarin dosing algorithms do not account for genetic mutations that can affect anticoagulation response. We retrospectively assessed to what extent the VKORC1 variant genotype would alter the likelihood of being a hyperresponder or hyporesponder to warfarin in patients undergoing total joint arthroplasty. We used the international normalized ratio (INR) on the third postoperative day of 3.0 or greater to define warfarin hyperresponders and 1.07 or less to define hyporesponders. A control group of normal responders was identified. From a cohort of 1125 patients receiving warfarin thromboprophylaxis, we identified 30 free of predisposing factors that could affect warfarin response: 10 hyperresponders, eight hyporesponders, and 12 normal responders. Homozygous carriers of the VKORC1 mutant AA genotype were more likely (compared with carriers of GA or GG genotypes) to be hyperresponders (odds ratio, 7.5; 95% confidence interval, 1.04-54.1). Homozygous carriers of the GG (normal) genotype were more likely (compared with carriers of AA or GA genotypes) to be hyporesponders (odds ratio, 9; 95% confidence interval, 1.14-71). Preoperative screening for the VKORC-1 genotype could identify patients with a greater potential for being a hyperresponder or hyporesponder to warfarin. This may allow an adjusted pharmacogenetic-based warfarin dose to optimize anticoagulation, reducing postoperative risks of bleeding and thrombosis or embolism.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Prevention of postoperative venous thromboembolism in Japanese patients undergoing total hip or knee arthroplasty: two randomized, double-blind, placebo-controlled studies with three dosage regimens of enoxaparin

BACKGROUND

Enoxaparin is a low-molecular-weight heparin indicated in Europe and North America for the prevention of venous thromboembolism (VTE) in patients undergoing major orthopedic surgery. Registration trials of enoxaparin have been conducted primarily in Caucasian populations, and the efficacy and safety of enoxaparin in Japanese patients have not been demonstrated. We evaluated three dosage regimens of postoperative enoxaparin in Japanese patients undergoing elective total hip or knee arthroplasty.

METHODS

Two multicenter, randomized, double-blind studies enrolled 436 and 396 Japanese adults undergoing total hip or knee arthroplasty, respectively. The dosage regimens of enoxaparin were 20 mg once daily (qd), 40 mg qd, 20 mg twice daily (bid), or placebo for 14 consecutive days. The primary efficacy endpoint was the incidence of VTE in the modified intention-to-treat (mITT) population up to 15 days after surgery. VTE was defined as a composite of deep vein thrombosis (determined by venography) and symptomatic pulmonary embolism (confirmed by appropriate objective methods). Patients were also followed up at 90 days for VTE events. The primary safety outcome was the incidence of any bleeding during treatment and the follow-up period.

RESULTS

In the mITT populations, the incidence of VTE was 41.9% and 60.8% in the placebo groups after hip or knee arthroplasty, respectively, 25.9% and 44.9% in the enoxaparin 20 mg qd groups, 33.8% and 35.1% in the enoxaparin 40 mg qd groups, and 20.0% and 29.8% in the enoxaparin 20 mg bid groups. Only enoxaparin 20 mg bid significantly lowered the risk of VTE relative to placebo (by 52.2% and 51.0% after hip and knee arthroplasty, respectively). At the 90-day follow-up, no further cases of VTE were reported. In both the hip and knee studies, the four treatment groups did not differ significantly regarding the incidence of patients with any bleeding.

CONCLUSIONS

Our findings support the use of enoxaparin (20 mg bid daily, commencing 24-36 h postoperatively) in Japanese patients undergoing total hip or knee arthroplasty.

Extended duration rivaroxaban versus short-term enoxaparin for the prevention of venous thromboembolism after total hip arthroplasty: a double-blind, randomised controlled trial

BACKGROUND

The risk of venous thromboembolism is high after total hip arthroplasty and could persist after hospital discharge. Our aim was to compare the use of rivaroxaban for extended thromboprophylaxis with short-term thromboprophylaxis with enoxaparin.

METHODS

2509 patients scheduled to undergo elective total hip arthroplasty were randomly assigned, stratified according to centre, with a computer-generated randomisation code, to receive oral rivaroxaban 10 mg once daily for 31-39 days (with placebo injection for 10-14 days; n=1252), or enoxaparin 40 mg once daily subcutaneously for 10-14 days (with placebo tablet for 31-39 days; n=1257). The primary efficacy outcome was the composite of deep-vein thrombosis (symptomatic or asymptomatic detected by mandatory, bilateral venography), non-fatal pulmonary embolism, and all-cause mortality up to day 30-42. Analyses were done in the modified intention-to-treat population, which consisted of all patients who had received at least one dose of study medication, had undergone planned surgery, and had adequate assessment of thromboembolism. This study is registered at ClinicalTrials.gov, number NCT00332020.

FINDINGS

The modified intention-to-treat population for the analysis of the primary efficacy outcome consisted of 864 patients in the rivaroxaban group and 869 in the enoxaparin group. The primary outcome occurred in 17 (2.0%) patients in the rivaroxaban group, compared with 81 (9.3%) in the enoxaparin group (absolute risk reduction 7.3%, 95% CI 5.2-9.4; p<0.0001). The incidence of any on-treatment bleeding was much the same in both groups (81 [6.6%] events in 1228 patients in the rivaroxaban safety population vs 68 [5.5%] of 1229 patients in the enoxaparin safety population; p=0.25).

INTERPRETATION

Extended thromboprophylaxis with rivaroxaban was significantly more effective than short-term enoxaparin plus placebo for the prevention of venous thromboembolism, including symptomatic events, in patients undergoing total hip arthroplasty.