The effect of aspirin and low-molecular-weight heparin on venous thromboembolism after hip replacement: a non-randomised comparison from information in the National Joint Registry

The efficacy of aspirin versus low-molecular-weight heparin for venous thromboembolism prophylaxis after knee and hip arthroplasty: A systematic review and meta-analysis of randomized controlled trials

PURPOSE

The purpose of this study was to assess the efficacy of aspirin versus low-molecular-weight heparin (LMWH) in preventing venous thromboembolism (VTE) following hip and knee arthroplasty.

METHODS

PubMed/Medline, Embase, Cochrane Library and Google Scholar databases were searched from inception till June 2024 for original trials investigating the outcomes of aspirin versus LMWH in hip and knee arthroplasty. The primary outcome was VTE. Secondary outcomes included minor and major bleeding events, and postoperative mortality within 90 days. This review was conducted per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

A total of 7 randomized controlled trials with 12,134 participants were included. The mean ages for the aspirin and LMWH cohorts were 66.6 (57.6-69.0) years and 66.8 (57.9-68.9) years, respectively. There was no statistically significant difference in the overall risk of VTE between the aspirin and the LMWH cohorts (odds ratio [OR]: 0.95; 95% confidence interval [CI]: 0.48-1.89; p: 0.877). A subanalysis based on the specific VTE entity (pulmonary embolism [PE] or deep venous thrombosis) showed a significantly higher PE risk for patients receiving aspirin than the LMWH cohort (OR: 1.79; 95% CI: 1.11-2.89; p: 0.017). There was no difference in minor (OR: 0.64; 95% CI: 0.40-1.04; p: 0.072) and major bleeding (OR: 0.77; 95% CI: 0.40-1.47; p: 0.424) episodes across both groups. Furthermore, subanalysis among the total knee arthroplasty group showed that the aspirin cohort was significantly more likely to suffer VTEs than their LMWH counterparts (OR: 1.55; 95% CI: 1.21-1.98; p < 0.001).

CONCLUSION

This study demonstrated a significantly higher risk of PE among patients receiving aspirin compared to LMWH following hip or knee arthroplasty for osteoarthritis. Aspirin was associated with a significantly higher overall VTE risk among patients undergoing knee arthroplasty, in particular. This might suggest the inferiority of aspirin compared to LMWH in preventing VTE following such procedures.

LEVEL OF EVIDENCE

Level I.

Efficacy and safety of commonly used thromboprophylaxis agents following hip and knee arthroplasty

Aims

We investigated the efficacy and safety profile of commonly used venous thromboembolism (VTE) prophylaxis agents following hip and knee arthroplasty.

Methods

A systematic search of PubMed, Embase, Cochrane Library, Web of Science, and OrthoSearch was performed. Prophylaxis agents investigated were aspirin (< 325 mg and ≥ 325 mg daily), enoxaparin, dalteparin, fondaparinux, unfractionated heparin, warfarin, rivaroxaban, apixaban, and dabigatran. The primary efficacy outcome of interest was the risk of VTE, whereas the primary safety outcomes of interest were the risk of major bleeding events (MBE) and wound complications (WC). VTE was defined as the confirmed diagnosis of any deep vein thrombosis and/or pulmonary embolism. Network meta-analysis combining direct and indirect evidence was performed. Cluster rank analysis using the surface under cumulative ranking (SUCRA) was applied to compare each intervention group, weighing safety and efficacy outcomes.

Results

Of 86 studies eligible studies, cluster rank analysis showed that aspirin < 325 mg daily (SUCRA-VTE 89.3%; SUCRA-MBE 75.3%; SUCRA-WC 71.1%), enoxaparin (SUCRA-VTE 55.7%; SUCRA-MBE 49.8%; SUCRA-WC 45.2%), and dabigatran (SUCRA-VTE 44.9%; SUCRA-MBE 52.0%; SUCRA-WC 41.9%) have an overall satisfactory efficacy and safety profile.

Conclusion

We recommend the use of either aspirin < 325 mg daily, enoxaparin, or dabigatran for VTE prophylaxis following hip and knee arthroplasty.

[Translated article] Risk of venous thromboembolism in thromboprophylaxis between aspirin and low molecular weight heparins after total hip arthroplasty or total knee arthroplasty: Systematic review and meta-analysis

INTRODUCTION

The aim of this study was to evaluate the efficacy of aspirin versus low molecular weight heparins (LMWH) for the prophylaxis of venous thromboembolism (VTE), deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients undergoing total knee arthroplasty (TKA) and/or total hip arthroplasty (THA).

MATERIALS AND METHODS

Systematic review and meta-analysis. Sixteen studies were selected. The risk of VTE, DVT and PE were analysed. Mortality, risk of bleeding and surgical wound complications was also analysed.

RESULTS

248,461 patients were included. 176,406 patients with thromboprophylaxis with LMWH and 72,055 patients with aspirin thromboprophylaxis. There were no significant differences in the risk of VTE (OR=0.93; 95% CI: 0.69-1.26; p=0.64), DVT (OR=0.72; 95% CI: 0.43-1.20; p=0.21) or PE (OR=1.13; 95% CI: 0.86-1.49; p=0.38) between both groups. No significant differences were found in mortality (p=0.30), bleeding (p=0.22), or complications in the surgical wound (p=0.85) between both groups. These same findings were found in the sub-analysis of only randomised clinical trials (p>0.05).

CONCLUSIONS

No increased risk of PE, DVT, or VTE was found among patients with aspirin thromboprophylaxis versus patients with LMWH thromboprophylaxis. There was also no greater mortality, greater bleeding, or greater complications in the surgical wound found among patients with aspirin thromboprophylaxis versus patients with LMWH thromboprophylaxis.

Venous Thromboembolism in Foot and Ankle Trauma

Every surgeon may have experienced a tragic event associated with death or debilitation secondary to deep vein thrombosis (DVT) or pulmonary embolism (PE) after foot and ankle trauma and surgery. Nevertheless, the prevention of such a tragic event needs to be carefully evaluated rationally with currently available epidemiologic data. With great postoperative protocols and access to care, most PE events can be prevented. There are modifiable risk factors, such as length/type of immobilization and operative trauma/time that can lower the incidence of DVT/PE. In addition, chemical prophylaxis may be warranted in certain people within the foot and ankle trauma population.

Risk of venous thromboembolism in thromboprophylaxis between aspirin and low molecular weight heparins after total hip arthroplasty or total knee arthroplasty: Systematic review and meta-analysis

INTRODUCTION

The aim of this study was to evaluate the efficacy of aspirin versus low molecular weight heparins (LMWH) for the prophylaxis of venous thromboembolism (VTE), deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients undergoing total knee arthroplasty (TKA) and/or total hip arthroplasty (THA).

MATERIALS AND METHODS

Systematic review and meta-analysis. Sixteen studies were selected. The risk of VTE, DVT and PE were analyzed. Mortality, risk of bleeding and surgical wound complications was also analyzed.

RESULTS

248,461 patients were included. 176,406 patients with thromboprophylaxis with LMWH and 72,055 patients with aspirin thromboprophylaxis. There were no significant differences in the risk of VTE (OR = 0.93; 95% CI: 0.69-1.26; P = .64), DVT (OR = 0.72; 95% CI: 0.43-1.20; P = .21) or PE (OR = 1.13; 95% CI: 0.86-1.49; P = .38) between both groups. No significant differences were found in mortality (P = .30), bleeding (P = .22), or complications in the surgical wound (P = .85) between both groups. These same findings were found in the sub-analysis of only randomized clinical trials (P>.05).

CONCLUSIONS

No increased risk of PE, DVT, or VTE was found among patients with aspirin thromboprophylaxis versus patients with LMWH thromboprophylaxis. There was also no greater mortality, greater bleeding, or greater complications in the surgical wound found among patients with aspirin thromboprophylaxis versus patients with LMWH thromboprophylaxis.

Aspirin or enoxaparin for VTE prophylaxis after primary partial, total or revision hip or knee arthroplasty: A secondary analysis from the CRISTAL cluster randomized trial

BACKGROUND

This study compares aspirin to enoxaparin for symptomatic VTE prophylaxis within 90 days of any type of hip or knee arthroplasty performed for any diagnosis, in patients enrolled in the CRISTAL trial.

MATERIALS AND METHODS

CRISTAL was a cluster-randomised crossover, registry-nested non-inferiority trial across 31 hospitals in Australia. The primary publication was restricted to patients undergoing primary total hip or knee arthroplasty for a diagnosis of osteoarthritis. This report includes all enrolled patients undergoing hip or knee arthroplasty procedures (partial or total, primary or revision) performed for any indication. Hospitals were randomized to administer patients aspirin (100mg daily) or enoxaparin (40mg daily), for 35 days after hip arthroplasty and 14 days after knee arthroplasty. Crossover occurred after the patient enrolment target had been met for the first group. The primary outcome was symptomatic VTE within 90 days. Analyses were performed by randomization group.

RESULTS

Between April 20, 2019 and December 18, 2020, 12384 patients were enrolled (7238 aspirin group and 5146 enoxaparin). Of these, 6901 (95.3%) given aspirin and 4827 (93.8%) given enoxaparin (total 11728, 94.7%) were included in the final analyses. Within 90 days, symptomatic VTE occurred in 226 (3.27%) aspirin patients and 85 (1.76%) enoxaparin patients, significant for the superiority of enoxaparin (estimated treatment difference 1.85%, 95% CI 0.59% to 3.10%, p = 0.004). Joint-related reoperation within 90 days was lower in the enoxaparin group (109/4827 (2.26%) vs 171/6896 (2.47%) with aspirin, estimated difference 0.77%; 95% CI 0.06% to 1.47%, p = 0.03). There were no significant differences in the other secondary outcomes.

CONCLUSION

In patients undergoing hip or knee arthroplasty (of any type, performed for any indication) enrolled in the CRISTAL trial, aspirin compared to enoxaparin resulted in a significantly higher rate of symptomatic VTE and joint-related reoperation within 90 days. These findings extend the applicability of the CRISTAL trial results.

TRIAL REGISTRATION

Anzctr.org.au, identifier: ACTRN12618001879257.

Evaluation of venous thromboembolism risk assessment models for hospital inpatients: the VTEAM evidence synthesis

Background

Pharmacological prophylaxis during hospital admission can reduce the risk of acquired blood clots (venous thromboembolism) but may cause complications, such as bleeding. Using a risk assessment model to predict the risk of blood clots could facilitate selection of patients for prophylaxis and optimise the balance of benefits, risks and costs.

Objectives

We aimed to identify validated risk assessment models and estimate their prognostic accuracy, evaluate the cost-effectiveness of different strategies for selecting hospitalised patients for prophylaxis, assess the feasibility of using efficient research methods and estimate key parameters for future research.

Design

We undertook a systematic review, decision-analytic modelling and observational cohort study conducted in accordance with Enhancing the QUAlity and Transparency Of health Research (EQUATOR) guidelines.

Setting

NHS hospitals, with primary data collection at four sites.

Participants

Medical and surgical hospital inpatients, excluding paediatric, critical care and pregnancy-related admissions.

Interventions

Prophylaxis for all patients, none and according to selected risk assessment models.

Main outcome measures

Model accuracy for predicting blood clots, lifetime costs and quality-adjusted life-years associated with alternative strategies, accuracy of efficient methods for identifying key outcomes and proportion of inpatients recommended prophylaxis using different models.

Results

We identified 24 validated risk assessment models, but low-quality heterogeneous data suggested weak accuracy for prediction of blood clots and generally high risk of bias in all studies. Decision-analytic modelling showed that pharmacological prophylaxis for all eligible is generally more cost-effective than model-based strategies for both medical and surgical inpatients, when valuing a quality-adjusted life-year at £20,000. The findings were more sensitive to uncertainties in the surgical population; strategies using risk assessment models were more cost-effective if the model was assumed to have a very high sensitivity, or the long-term risks of post-thrombotic complications were lower. Efficient methods using routine data did not accurately identify blood clots or bleeding events and several pre-specified feasibility criteria were not met. Theoretical prophylaxis rates across an inpatient cohort based on existing risk assessment models ranged from 13% to 91%.

Limitations

Existing studies may underestimate the accuracy of risk assessment models, leading to underestimation of their cost-effectiveness. The cost-effectiveness findings do not apply to patients with an increased risk of bleeding. Mechanical thromboprophylaxis options were excluded from the modelling. Primary data collection was predominately retrospective, risking case ascertainment bias.

Conclusions

Thromboprophylaxis for all patients appears to be generally more cost-effective than using a risk assessment model, in hospitalised patients at low risk of bleeding. To be cost-effective, any risk assessment model would need to be highly sensitive. Current evidence on risk assessment models is at high risk of bias and our findings should be interpreted in this context. We were unable to demonstrate the feasibility of using efficient methods to accurately detect relevant outcomes for future research.

Future work

Further research should evaluate routine prophylaxis strategies for all eligible hospitalised patients. Models that could accurately identify individuals at very low risk of blood clots (who could discontinue prophylaxis) warrant further evaluation.

Study registration

This study is registered as PROSPERO CRD42020165778 and Researchregistry5216.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR127454) and will be published in full in Health Technology Assessment; Vol. 28, No. 20. See the NIHR Funding and Awards website for further award information.

Comparative effectiveness of aspirin for symptomatic venous thromboembolism prophylaxis in patients undergoing total joint arthroplasty, a cohort study

BACKGROUND

This study compares the symptomatic 90-day venous thromboembolism (VTE) rates in patients receiving aspirin to patients receiving low-molecular weight heparin (LMWH) or direct oral anticoagulants (DOACs), after total hip (THA) and total knee arthroplasty (TKA).

METHODS

Data were collected from a multi-centre cohort study, including demographics, confounders and prophylaxis type (aspirin alone, LMWH alone, aspirin and LMWH, and DOACs). The primary outcome was symptomatic 90-day VTE. Secondary outcomes were major bleeding, joint related reoperation and mortality within 90 days. Data were analysed using logistic regression, the Student's t and Fisher's exact tests (unadjusted) and multivariable regression (adjusted).

RESULTS

There were 1867 eligible patients; 365 (20%) received aspirin alone, 762 (41%) LMWH alone, 482 (26%) LMWH and aspirin and 170 (9%) DOAC. The 90-day VTE rate was 2.7%; lowest in the aspirin group (1.6%), compared to 3.6% for LMWH, 2.3% for LMWH and aspirin and 2.4% for DOACs. After adjusted analysis, predictors of VTE were prophylaxis duration < 14 days (OR = 6.7, 95% CI 3.5-13.1, p < 0.001) and history of previous VTE (OR = 2.4, 95% CI 1.1-5.8, p = 0.05). There were no significant differences in the primary or secondary outcomes between prophylaxis groups.

CONCLUSIONS

Aspirin may be suitable for VTE prophylaxis following THA and TKA. The comparatively low unadjusted 90-day VTE rate in the aspirin group may have been due to selective use in lower-risk patients.

TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov, trial number NCT01899443 (15/07/2013).

Effect of Aspirin vs Enoxaparin on 90-Day Mortality in Patients Undergoing Hip or Knee Arthroplasty: A Secondary Analysis of the CRISTAL Cluster Randomized Trial

Importance

Ischemic heart disease remains the leading cause of mortality following hip and knee arthroplasty. Due to its antiplatelet and cardioprotective properties, aspirin has been proposed as an agent that could reduce mortality when used as venous thromboembolism (VTE) prophylaxis following these procedures.

Objective

To compare aspirin with enoxaparin in reducing 90-day mortality for patients undergoing hip or knee arthroplasty procedures.

Design, Setting, and Participants

This study was a planned secondary analysis of the CRISTAL cluster randomized, crossover, registry-nested trial performed across 31 participating hospitals in Australia between April 20, 2019, and December 18, 2020. The aim of the CRISTAL trial was to determine whether aspirin was noninferior to enoxaparin in preventing symptomatic VTE following hip or knee arthroplasty. The primary study restricted the analysis to patients undergoing total hip or knee arthroplasty for a diagnosis of osteoarthritis only. This study includes all adult patients (aged ≥18 years) undergoing any hip or knee arthroplasty procedure at participating sites during the course of the trial. Data were analyzed from June 1 to September 6, 2021.

Interventions

Hospitals were randomized to administer all patients oral aspirin (100 mg daily) or subcutaneous enoxaparin (40 mg daily) for 35 days after hip arthroplasty and 14 days after knee arthroplasty procedures.

Main Outcomes and Measures

The primary outcome was mortality within 90 days. The between-group difference in mortality was estimated using cluster summary methods.

Results

A total of 23 458 patients from 31 hospitals were included, with 14 156 patients allocated to aspirin (median [IQR] age, 69 [62-77] years; 7984 [56.4%] female) and 9302 patients allocated to enoxaparin (median [IQR] age, 70 [62-77] years; 5277 [56.7%] female). The mortality rate within 90 days of surgery was 1.67% in the aspirin group and 1.53% in the enoxaparin group (estimated difference, 0.04%; 95% CI, -0.05%-0.42%). For the subgroup of 21 148 patients with a nonfracture diagnosis, the mortality rate was 0.49% in the aspirin group and 0.41% in the enoxaparin group (estimated difference, 0.05%; 95% CI, -0.67% to 0.76%).

Conclusions and Relevance

In this secondary analysis of a cluster randomized trial comparing aspirin with enoxaparin following hip or knee arthroplasty, there was no significant between-group difference in mortality within 90 days when either drug was used for VTE prophylaxis.

Trial Registration

http://anzctr.org.au Identifier: ACTRN12618001879257.

Efficacy and Safety of Thromboprophylaxis Post-Orthopedic Surgery

Given the high risk of venous thromboembolism (VTE) post-orthopedic surgery and the vital role of thromboprophylaxis in preventing VTEs, this meta-analysis aimed to assess the efficacy of thromboprophylaxis post major orthopedic surgery and the relevant safety measures. In this review, we conducted a computer-aided search of Google Scholar, PubMed, CINAHL, Cochrane, Medline, and EMBASE databases. We included all published randomized clinical trials (RCTs) that utilized enoxaparin, fondaparinux, dabigatran, rivaroxaban, apixaban, and aspirin for VTE prophylaxis in patients undergoing total hip arthroplasty (THA), hip fracture surgery, and total knee arthroplasty (TKA) based on primary and secondary outcomes. The Cochrane Collaboration tool was used to evaluate the risk of bias. All statistical analyses were performed using Review Manager Software. A total of 23 RCTs were included with a total sample of 48,424 patients and an overall low risk of bias. The efficacy of enoxaparin in preventing VTEs in the TKA group was significantly better than fondaparinux. In the THA group, the efficacy of enoxaparin was significantly better than apixaban. The efficacies of fondaparinux, dabigatran, rivaroxaban, apixaban, and aspirin were comparable to that of enoxaparin in reducing VTE-associated mortality, major bleeding, and adverse events. In conclusion, we found that all included drugs were non-inferior to enoxaparin in VTE-associated mortality, major bleeding, and adverse events.

Aspirin Compared With Other Anticoagulants for Use as Venous Thromboembolism Prophylaxis in Elective Orthopaedic Hip and Knee Operations: A Narrative Literature Review

Although total hip and knee arthroplasty are effective methods for treating arthritis, they have an associated risk of venous thromboembolism (VTE). To reduce this risk, prophylactic agents including aspirin, low-molecular-weight Heparin, vitamin K antagonists, and direct oral anticoagulants are employed for up to 35 days after surgery. This narrative literature review utilised a systematic approach to critically assess the current evidence surrounding the use of aspirin for VTE prophylaxis compared to anticoagulants. An advanced multistage electronic search was performed in May 2021 using the OVID/Medline and Embase online libraries to identify available studies relevant to the subject from 1974. Additional studies identified during the review process were also included. The final studies meeting the inclusion criteria were then assessed using the Critical Appraisal Skills Programme tool. A total of 12 (60%) studies (two meta-analyses, three randomised trials, seven retrospective studies) favoured aspirin over anticoagulants for VTE prophylaxis. A total of 15 (75%) studies (two meta-analyses, three randomised trials, nine retrospective, one matched cohort) reported that aspirin had better bleeding profiles and complication rates, which was statistically significant in seven (46.7%) studies (one randomised trial, six retrospective studies). A total of eight studies (one randomised trial, six retrospective studies, one matched cohort) reported statistically significant results for aspirin. Five (62.5%) studies reported aspirin to be superior for VTE prophylaxis, while seven (87.5%) reported aspirin to be superior in terms of bleeding complications. The current evidence indicates that aspirin is superior to anticoagulants, in their various iterations, for VTE prophylaxis in terms of their bleeding profiles.

CRISTAL (a cluster-randomised, crossover, non-inferiority trial of aspirin compared to low molecular weight heparin for venous thromboembolism prophylaxis in hip or knee arthroplasty, a registry nested study): statistical analysis plan

BACKGROUND

This a priori statistical analysis plan describes the analysis for CRISTAL.

METHODS

CRISTAL (cluster-randomised, crossover, non-inferiority trial of aspirin compared to low molecular weight heparin for venous thromboembolism prophylaxis in hip or knee arthroplasty, a registry nested study) aims to determine whether aspirin is non-inferior to low molecular weight heparin (LMWH) in preventing symptomatic venous thromboembolism (VTE) following hip arthroplasty (HA) or knee arthroplasty (KA). The study is nested within the Australian Orthopaedic Association National Joint Replacement Registry. The trial was commenced in April 2019 and after an unplanned interim analysis, recruitment was stopped (December 2020), as the stopping rule was met for the primary outcome. The clusters comprised hospitals performing > 250 HA and/or KA procedures per annum, whereby all adults (> 18 years) undergoing HA or KA were recruited. Each hospital was randomised to commence with aspirin, orally, 85-150 mg daily or LMWH (enoxaparin), 40 mg, subcutaneously, daily within 24 h postoperatively, for 35 days after HA and 14 days after KA. Crossover was planned once the registration target was met for the first arm. The primary end point is symptomatic VTE within 90 days. Secondary outcomes include readmission, reoperation, major bleeding and death within 90 days, and reoperation and patient-reported pain, function and health status at 6 months. The main analyses will focus on the primary and secondary outcomes for patients undergoing elective primary total HA and KA for osteoarthritis. The analysis will use an intention-to-treat approach with cluster summary methods to compare treatment arms. As the trial stopped early, analyses will account for incomplete cluster crossover and unequal cluster sizes.

CONCLUSIONS

This paper provides a detailed statistical analysis plan for CRISTAL.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ACTRN12618001879257 . Registered on 19/11/2018.

Venous Thromboembolic Prophylaxis After Total Hip and Knee Arthroplasty

➤

The selection of an agent for prophylaxis against venous thromboembolism (VTE) is a balance between efficacy and safety. The goal is to prevent symptomatic VTE while limiting the risk of bleeding.

➤

The optimal agent for VTE prophylaxis has not been identified. The American College of Chest Physicians guidelines recommend that, after total hip or total knee arthroplasty, patients receive at least 10 to 14 days of 1 of the following prophylaxis agents: aspirin, adjusted-dose vitamin K antagonist, apixaban, dabigatran, fondaparinux, low-molecular-weight heparin, low-dose unfractionated heparin, rivaroxaban, or portable home mechanical compression.

➤

The use of aspirin for VTE prophylaxis has increased in popularity over the past decade because it is effective, and it is an oral agent that does not require monitoring. The true efficacy of aspirin needs to be determined in multicenter randomized clinical trials.

➤

Validated risk stratification protocols are essential to identify the safest and most effective regimen for VTE prophylaxis for individual patients. There is no consensus regarding the optimal method for risk stratification; the selection of a prophylaxis agent should be determined by shared decision-making with the patient to balance the risk of thrombosis versus bleeding.

➤

Patients with atrial fibrillation being treated with chronic warfarin therapy or direct oral anticoagulants should stop the agent 3 to 5 days prior to surgery. Patients do not typically require bridging therapy prior to surgery.

A modeling approach to derive baseline risk estimates for GRADE recommendations:Concepts, development, and results of its application to the American Society of Hematology 2019 guidelines on prevention of venous thromboembolism in surgical hospitalized patients

OBJECTIVE

The goal of this study was to develop an approach that can be used where baseline risk estimates that are directly applicable to prioritized patient-important outcomes are not available from published studies.

STUDY DESIGN

The McMaster University GRADE Centre and the ASH guideline panel for the prevention of VTE in surgical patients developed a modeling approach based on explicit assumptions about the distribution of symptoms, anatomical location, and severity of VTE events.

RESULTS

We applied the approach to derive modeled estimates of baseline risk. These estimates were used to calculated absolute measures of anticipated effects that informed the discussion of the evidence and the formulation of 30 guideline recommendations.

CONCLUSIONS

Our approach can assist guideline developers facing a lack of information about baseline risk estimates that directly apply to outcomes of interest. The use of modeled estimates increases transparency in the process and makes the baseline risk used by guideline experts explicit during their decision-making.

Is Apixaban Safe and Effective for Venous Thromboembolism Prophylaxis After Primary Total Hip and Total Knee Arthroplasties?

BACKGROUND

Venous thromboembolism (VTE) is a serious complication of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Apixaban is approved for VTE prophylaxis. This study seeks to ascertain the risk of VTE and bleeding complications in patients undergoing primary THA and TKA receiving apixaban for postoperative VTE prophylaxis for one of the following indications: high risk for VTE, previously on apixaban, and contraindication to the use of aspirin.

METHODS

This is a retrospective cohort study of patients who underwent primary THA or TKA over a 17-month period and were prescribed apixaban for thromboprophylaxis postoperatively.

RESULTS

230 patients were included in the study, 110 TKA and 120 THA. The primary reasons for high-risk VTE status included personal and family history of VTE, and 13% were taking apixaban preoperatively for atrial fibrillation. 1 patient (0.43%) who underwent TKA had a DVT with PE. 2.6% of patients had wound complications requiring operative treatment, and 0.87% of THA patients underwent revision arthroplasty.

CONCLUSION

The use of apixaban for VTE prophylaxis after primary THA and TKA in patients at high risk for VTE, in patients previously on apixaban, and in patients with a contraindication to the use of aspirin is associated with a low risk of VTE and bleeding complications.

Utilization Patterns, Efficacy, and Complications of Venous Thromboembolism Prophylaxis Strategies in Revision Hip and Knee Arthroplasty as Reported by American Board of Orthopaedic Surgery Part II Candidates

BACKGROUND

The optimum venous thromboembolism (VTE) prophylaxis strategy to minimize risk of VTE and bleeding complications following revision total hip and knee arthroplasty (rTHA/rTKA) is controversial. The purpose of this study is to describe current VTE prophylaxis patterns following revision arthroplasty procedures to determine efficacy, complication rates, and prescribing patterns for different prophylactic strategies.

METHODS

The American Board of Orthopaedic Surgery Part II (oral) examination case list database was analyzed. Current Procedural Terminology codes for rTHA/rTKA were queried and geographic region, VTE prophylaxis strategy, and complications were obtained. Less aggressive prophylaxis patterns were defined if only aspirin and/or sequential compression devises were utilized. More aggressive VTE prophylaxis patterns were considered if any of low-molecular-weight heparin (enoxaparin), warfarin, rivaroxaban, fondaparinux, or other strategies were used.

RESULTS

In total, 6387 revision arthroplasties were included. The national rate of less aggressive VTE prophylaxis strategies was 35.3% and more aggressive in 64.7%. Use of less aggressive prophylaxis strategy was significantly associated with patients having no complications (89.8% vs 81.9%, P < .001). Use of more aggressive prophylaxis patterns was associated with higher likelihood of mild thrombotic (1.2% vs 0.3%, P < .001), mild bleeding (1.7% vs 0.6%, P < .001), moderate thrombotic (2.6% vs 0.4%, P < .001), moderate bleeding (6.2% vs 4.0%, P < .001), severe bleeding events (4.4% vs 2.4%, P < .001), infections (6.4% vs 3.8%, P < .001), and death within 90 days (3.1% vs 1.3%, P < .001). There were no significant differences in rates of fatal pulmonary embolism (0.1% vs 0.04%, P = .474). Subgroup analysis of rTHA and rTKA patients showed similar results.

CONCLUSION

The individual rationale for using a more aggressive VTE prophylaxis strategy was unknown; however, more aggressive strategies were associated with higher rates of bleeding and thrombotic complications. Less aggressive strategies were not associated with a higher rate of thrombosis.

LEVEL OF EVIDENCE

Therapeutic Level III.

Aspirin versus enoxaparin for the initial prevention of venous thromboembolism following elective arthroplasty of the hip or knee: A systematic review and meta-analysis

BACKGROUND

Aspirin is perceived to be non-inferior to enoxaparin, a low-molecular-weight heparin, for the prevention of venous thromboembolism (VTE) following elective arthroplasty of the hip or knee and is recommended in clinical guidelines internationally. Previous systematic reviews of aspirin as VTE prophylaxis have been limited by the inclusion of heterogenous studies where aspirin is commenced after the initial high-risk postoperative period. The purpose of this systematic review and meta-analysis was to compare the efficacy and associated harms of aspirin and enoxaparin when used as VTE prophylaxis in the initial postoperative period following elective arthroplasty of the hip or knee. We sought to: (1) to compare the use of aspirin versus enoxaparin following elective joint replacement of the hip or knee on the primary outcomes of incidence of VTE and mortality up to 3 months postoperatively and (2) assess the efficacy of aspirin with respect to secondary outcomes such as major or minor bleeding events. We hypothesised that aspirin would have equivalent efficacy for the prevention of VTE when used as initial prophylactic agent, without increasing harm from bleeding events.

PATIENTS AND METHODS

We searched Pubmed, Embase, Medline and Cochrane Central for randomized controlled trials reporting the primary outcomes of VTE incidence and mortality. Secondary outcomes included major (compromise of organ, limb or muscle function requiring unplanned re-operation) and minor bleeding events (wound ooze, minor bleed, infection). Included trials underwent a risk of bias and quality of evidence assessment using the GRADE criteria.

RESULTS

Four trials involving 1507 participants who underwent elective lower limb arthroplasty were included. We did not detect a significant difference in overall VTE rates when comparing aspirin versus enoxaparin (RR, 0.84; 95% CI: 0.41 to 1.75; p=0.65). Mortality was reported by one study and no events were recorded. There were no significant differences in the rates of all major (RR, 0.84; 95% CI: 0.08 to 9.16) or minor (RR, 0.77; 95% CI: 0.34 to 1.72) bleeding events between the aspirin and enoxaparin groups. Included trials demonstrated a significant risk of bias, and Low to Very Low quality of evidence for primary outcomes, and Moderate to Very Low for secondary outcomes.

CONCLUSION

There is currently a lack of high quality randomised controlled trials supporting the use of aspirin as VTE chemoprophylaxis in the initial postoperative period for both total hip and total knee arthroplasty. The results of this meta-analysis provide cautious endorsement for the position that aspirin is likely a safe alternative to enoxaparin for TKA patients as part of a multimodal enhanced recovery protocol, but care is advised for THA patients owing to a lack of data from trials. Current evidence from randomized controlled trials is generally of low quality, and does not estimate critical event data for VTE incidence or mortality, as well as major and minor bleeding events with sufficient certainty. PROSPERO Registration CRD42018110784.

LEVEL OF EVIDENCE

II, systematic review.

Risk-Stratified Venous Thromboembolism Prophylaxis after Total Joint Arthroplasty: Low Molecular Weight Heparins and Sequential Aspirin vs Aggressive Chemoprophylaxis

OBJECTIVE

Venous thromboembolism (VTE) is a significant concern post total joint arthroplasty (TJA). However, the optimal prevention method of VTE remains controversial at present. This study aims to evaluate a risk-stratified VTE prophylaxis protocol for patients undergoing TJA.

METHODS

A total of 891 TJA patients from January 2011 to November 2019 were retrospectively investigated. The study was divided into two cohorts. In cohort 1, 410 patients (250 females and 160 males, mean age 64.32 years) were treated with an aggressive VTE chemoprophylaxis protocol. In cohort 2, 481 patients were treated with a risk-stratified protocol that utilized low molecular weight heparins (LMWH) and sequential aspirin (ASA) for standard-risk patients (a total of 288 containing 177 females and 111 males, mean age 65.4 years), and targeted anticoagulation for high-risk patients (a total of 193 containing 121 females and 72 males, mean age 66.8 years). The patients were followed up at 2-4 weeks for an initial visit and at 6-10 weeks for a subsequent visit after surgery. A chart review of all patient medical records was performed to record the demographics, comorbidities, deep vein thrombosis, pulmonary embolus, superficial infection, deep infection, bleeding complications, and 90-day readmissions.

RESULTS

The VTE rate was 1.71% (7/410) in cohort 1 and 1.46% (7/481) in cohort 2 respectively. For cohort 2, the VTE rate was 2.07% (4/193) in high-risk group and 1.04% (3/288) in standard-risk group. The readmission rate was 2.44% (10/410) in cohort 1 and 2.08% (10/481) in cohort 2. For cohort 2, the readmission rate was 2.07% (4/193) in high-risk group and 2.08% (6/288) in standard-risk group. The reasons for readmission were as follows: infection, 1.3% (5/410) in cohort 1 and 1.3% (6/481) in cohort 2; wound or bleeding complications, 0.48% (2/410) in cohort 1 and 0.2% (1/481) in cohort 2; trauma, 0.2% (1/410) in cohort 1 and 0.2% (1/481) in cohort 2; VTE, 0.2% (1/410) in cohort 1 and 0.2% (1/481) in cohort 2; others, 0.2% (1/410) in cohort 1 and 0.6% (3/481) in cohort 2. There was a decrease in VTE events and readmissions in the risk-stratified cohort, although this did not reach statistical significance. However, it was found that there was a significant reduction in costs (P < 0.001) with the use of LMWH/ASA, when compared with aggressive anticoagulation agents in the risk-stratified cohort.

CONCLUSION

The use of LMWH/ASA in a risk-stratified TJA population is a safe and cost-effective method of VTE prophylaxis.

No difference in patient compliance between full-strength versus low-dose aspirin for VTE prophylaxis following total hip and total knee replacement

INTRODUCTION

The utilization of aspirin for VTE prophylaxis following TJA has increased due to updated clinical practice guidelines. Aspirin is the only approved VTE prophylaxis medication that does not require a prescription, but adherence and tolerance remain unknown. We hypothesized decreased patient compliance utilizing full-strength 325 mg aspirin twice daily following TJA when compared to low-dose 81 mg twice daily. We also investigated the reasons why patients may elect to stop the medication earlier than 28 days.

METHODS

A consecutive series of patients undergoing primary total hip or knee arthroplasty utilizing 325 or 81 mg of EC aspirin twice daily for 4 weeks were surveyed to determine compliance with use and any adverse events related to the medication. Fisher's exact test was used to determine statistical significance.

RESULTS

404 patients were enrolled with 199 patients prescribed the 325 mg regimen. Fifty-two patients who were prescribed 325 mg missed a dose versus 51 patients who were prescribed 81 mg (p = 0.082). No significant difference in the frequency of missed doses (missing < 5 doses, 5-10 doses, > 10 doses) between the treatment regimens (p = 0.78, 0.39 and 0.83, respectively). Most commonly cited reason for stopping aspirin in both treatment groups was gastrointestinal issues (10.5% and 7%, respectively).

DISCUSSION AND CONCLUSIONS

By surveying patients on their use of aspirin we find no difference in adherence between full-strength and low-dose treatment regimens. Additionally, we have a better understanding of the reasons for noncompliance as GI upset was a relatively common complaint with both doses.

Is Aspirin as Effective as the Newer Direct Oral Anticoagulants for Venous Thromboembolism Prophylaxis After Total Hip and Knee Arthroplasty? An Analysis From the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man

BACKGROUND

Few studies have compared aspirin with direct oral anticoagulants (DOACs) (DOACs = direct thrombin inhibitors and factor Xa inhibitors) for venous thromboembolism (VTE) prophylaxis after total hip arthroplasty (THA) and total knee arthroplasty (TKA). We assessed the efficacy and safety of aspirin compared with DOACs for VTE prophylaxis after THA and TKA using the world's largest joint arthroplasty registry.

METHODS

We studied the National Joint Registry linked to English hospital inpatient episodes for 218,650 THA and TKA patients. Patients receiving aspirin were matched separately to patients receiving direct thrombin inhibitors and factor Xa inhibitors using propensity scores. Outcomes assessed at 90 days included VTE, length of stay, and adverse events.

RESULTS

After THA, there was a significantly lower risk of VTE associated with the use of direct thrombin inhibitors (0.44%; odds ratio [OR], 0.69; 95% confidence interval [95% CI], 0.55-0.87; P = .002) and factor Xa inhibitors (0.37%; OR, 0.63; 95% CI, 0.47-0.85; P = .003) compared with aspirin (0.63%). After THA, direct thrombin inhibitors (coefficient, -0.37 days; 95% CI, -0.43 to -0.31; P < .001) and factor Xa inhibitors (coefficient, -0.80 days; 95% CI, -0.87 to -0.74; P < .001) were associated with a reduced length of stay compared with aspirin. Similar findings for both outcomes were observed after TKA. Compared with aspirin, DOACs were not associated with an increase in the risk of short-term revision surgery, reoperation, major hemorrhage, wound disruption, surgical site infection, and mortality.

CONCLUSION

After THA and TKA, DOACs were associated with a reduced risk of VTE compared with aspirin. DOACs were associated with a reduced length of stay, and DOACs were not associated with an increase in the risk of further surgery, wound problems, bleeding complications, or mortality compared with aspirin.

Aspirin compared to enoxaparin or rivaroxaban for thromboprophylaxis following hip and knee replacement

Background The risk of venous thromboembolism following major orthopaedic surgery is among the highest for all surgical specialties. Our hospital guidelines for thromboprophylaxis following elective primary total hip or knee replacement are based on American College of Chest Physicians guidance. The most recent change to local guidelines was the introduction of the extended aspirin regimen as standard thromboprophylaxis. Objective To establish the appropriateness of this regimen by comparing venous thromboembolism rates in patients receiving extended aspirin to previous regimens. Setting The largest dedicated orthopaedic hospital in Ireland. Methods This was a retrospective cohort study. Data were collected from patient record software. All eligible patients undergoing primary total hip or knee replacement between 1st January 2010 and 30th June 2016 were included. Main outcome measure Venous thromboembolism up to 6 months post-operatively. Results Of the 6548 participants (55.3% female, mean age 65.4 years (± 11.8 years, 55.8% underwent total hip replacement), venous thromboembolism occurred in 65 (0.99%). Venous thromboembolism rate in both the inpatient enoxaparin group (n = 961) and extended aspirin group (n = 3460) was 1.04% and was 0.66% in the modified rivaroxaban group (n = 1212). Non-inferiority analysis showed the extended aspirin regimen to be equivalent to the modified rivaroxaban regimen. History of venous thromboembolism was the only significant demographic risk factor for post-operative venous thromboembolism (0.87% vs. 3.54%, p  = 0.0002). Conclusion In daily clinical practice, extended aspirin regimen is at least as effective as modified rivaroxaban for preventing clinically important venous thromboembolism among patients undergoing hip or knee arthroplasty who are discharged from the hospital without complications. Aspirin can be considered a safe and effective agent in the prevention of venous thromboembolism after total hip or total knee replacement.

Low-Dose Aspirin Is Adequate for Venous Thromboembolism Prevention Following Total Joint Arthroplasty: A Systematic Review

BACKGROUND

Patients undergoing total joint arthroplasty (TJA) are at risk of developing venous thromboembolism (VTE) without adequate prophylaxis. Since the American Academy of Orthopedic Surgeons issued guidelines in 2007 recommending aspirin 325 mg bis in die for 6 weeks, aspirin has been favored as the main VTE prophylaxis. However, the appropriate dose and duration of aspirin are not well-studied. This systematic review aims to identify any differences between high and low dose as well as duration for aspirin thromboprophylaxis after TJA as outlined by previous studies.

METHODS

A search was performed using Ovid MEDLINE, EMBASE, and PubMed, including articles up to July 2016. Studies were included if they contained at least 1 cohort that underwent TJA with aspirin as the sole chemoprophylaxis and reported either (1) symptomatic VTE or (2) secondary outcomes such as major bleeding or 90-day mortality.

RESULTS

Forty-five papers were included. There were no significant differences in symptomatic pulmonary embolism, symptomatic deep vein thrombosis, 90-day mortality, or major bleeding between patients receiving low-dose or high-dose aspirin. Patients treated with aspirin for <4 weeks had a higher risk of major bleeding (1.59%) vs patients treated for 4 weeks (0.15%), which may be attributed to premature cessation or differential reporting. Patients treated with aspirin for <4 weeks had a statistically higher 90-day mortality (1.95%) vs patients treated for 4 weeks (0.07%). There was no significant difference between incidence of pulmonary embolism or deep vein thrombosis and the durations of aspirin treatment.

CONCLUSION

This review suggests that low-dose aspirin is not inferior to high-dose aspirin for VTE thromboprophylaxis in TJA patients. Additionally, patients treated with aspirin for less than 4 weeks may have a higher risk of major bleeding and 90-day mortality compared to patients treated for a longer duration.

Clinical Effectiveness and Safety of Aspirin for Venous Thromboembolism Prophylaxis After Total Hip and Knee Replacement: A Systematic Review and Meta-analysis of Randomized Clinical Trials

IMPORTANCE

Patients undergoing total hip replacement (THR) and total knee replacement (TKR) receive venous thromboembolism (VTE) pharmacoprophylaxis. It is unclear which anticoagulant is preferable. Observational data suggest aspirin provides effective VTE prophylaxis.

OBJECTIVE

To assess the effectiveness and safety of aspirin for VTE prophylaxis after THR and TKR.

DATA SOURCES

A systematic review and meta-analysis was performed of randomized clinical trials (RCTs), with no language restrictions, from inception to September 19, 2019, using MEDLINE, Embase, Web of Science, Cochrane Library, and bibliographic searches. The computer-based searches combined terms and combinations of keywords related to the population (eg, hip replacement, knee replacement, hip arthroplasty, and knee arthroplasty), drug intervention (eg, aspirin, heparin, clexane, dabigatran, rivaroxaban, and warfarin), and outcome (eg, venous thromboembolism, deep vein thrombosis, pulmonary embolism, and bleeding) in humans.

STUDY SELECTION

This study included RCTs assessing the effectiveness and safety of aspirin for VTE prophylaxis compared with other anticoagulants in adults undergoing THR and TKR. The RCTs with a placebo control group were excluded. The searches and study selection were independently performed.

DATA EXTRACTION AND SYNTHESIS

This study followed PRISMA recommendations and used the Cochrane Collaboration's risk of bias tool. Data were screened and extracted independently by both reviewers. Study-specific relative risks (RRs) were aggregated using random-effects models. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

MAIN OUTCOMES AND MEASURES

The primary outcome was any postoperative VTE (asymptomatic or symptomatic). Secondary outcomes were adverse events associated with therapy, including bleeding.

RESULTS

Of 437 identified articles, 13 RCTs were included (6060 participants; 3466 [57.2%] women; mean age, 63.0 years). The RR of VTE after THR and TKR was 1.12 (95% CI, 0.78-1.62) for aspirin compared with other anticoagulants. Comparable findings were observed for deep vein thrombosis (DVT) (RR, 1.04; 95% CI, 0.72-1.51) and pulmonary embolism (PE) (RR, 1.01; 95% CI, 0.68-1.48). The risk of adverse events, including major bleeding, wound hematoma, and wound infection, was not statistically significantly different in patients receiving aspirin vs other anticoagulants. When analyzing THRs and TKRs separately, there was no statistically significant difference in the risk of VTE, DVT, and PE between aspirin and other anticoagulants. Aspirin had a VTE risk not statistically significantly different from low-molecular-weight heparin (RR, 0.76; 95% CI, 0.37-1.56) or rivaroxaban (RR, 1.52; 95% CI, 0.56-4.12). The quality of the evidence ranged from low to high.

CONCLUSIONS AND RELEVANCE

In terms of clinical effectiveness and safety profile, aspirin did not differ statistically significantly from other anticoagulants used for VTE prophylaxis after THR and TKR. Future trials should focus on noninferiority analysis of aspirin compared with alternative anticoagulants and cost-effectiveness.

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.

CRISTAL: protocol for a cluster randomised, crossover, non-inferiority trial of aspirin compared to low molecular weight heparin for venous thromboembolism prophylaxis in hip or knee arthroplasty, a registry nested study

INTRODUCTION

Venous thromboembolism (VTE) is a serious complication following hip arthroplasty (HA) and knee arthroplasty (KA). This study aims to determine whether aspirin is non-inferior to low molecular weight heparin (LMWH) in preventing symptomatic VTE following HA and KA.

METHODS AND ANALYSIS

This is a cluster randomised, crossover, non-inferiority, trial nested within the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). The clusters will consist of Australian hospitals performing at least 250 HA and/or KA procedures per annum. All adult patients undergoing HA or KA will be included. The intervention will be aspirin, orally, 85-150 mg daily. The comparator will be LMWH (enoxaparin) 40 mg, subcutaneously, daily. Both drugs will commence within 24 hours postoperatively and continue for 35 days after HA and 14 days after KA. Each hospital will be randomised to commence with aspirin or LMWH and then crossover to the alternative treatment after meeting the recruitment target. Data will be collected through the AOANJRR via patient-reported surveys. The primary outcome is symptomatic VTE within 90 days post surgery, verified by AOANJRR staff. The primary analysis will include only patients undergoing elective primary total hip arthroplasty and total knee arthroplasty for osteoarthritis. Secondary outcomes will include symptomatic VTE for all HA and KA (including partial and revision) within 90 days, readmission, reoperation, major bleeding and death within 90 days and reoperation, death and patient-reported pain, function and health status at 6 months. If aspirin is found to be inferior, a cost-effectiveness analysis will be conducted. The study will aim to recruit 15 562 patients from 31 hospitals.

ETHICS AND DISSEMINATION

Ethics approval has been granted. Trial results will be submitted for publication. The trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12618001879257, pre-results) and is endorsed by the Australia and New Zealand Musculoskeletal Clinical Trials Network.

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.

Utilization Patterns, Efficacy, and Complications of Venous Thromboembolism Prophylaxis Strategies in Primary Hip and Knee Arthroplasty as Reported by American Board of Orthopedic Surgery Part II Candidates

BACKGROUND

Many strategies for venous thromboembolism (VTE) prophylaxis following hip and knee arthroplasty exist, with extensive controversy regarding the optimum strategy to minimize risk of VTE and bleeding complications. Data from the American Board of Orthopedic Surgery Part II (oral) Examination case list database was analyzed to determine efficacy, complication rates, and prescribing patterns for different prophylactic strategies.

METHODS

The American Board of Orthopedic Surgery case database was queried utilizing Current Procedural Terminology codes 27447 and 27130 for primary total knee and hip arthroplasty, respectively. Geographic region, patient age, gender, deep vein thrombosis prophylaxis strategy, and complications were obtained. Less aggressive prophylaxis patterns were considered if only aspirin and/or sequential compression devises were utilized. More aggressive VTE prophylaxis patterns were considered if any of low-molecular-weight heparin (enoxaparin), warfarin, rivaroxaban, fondaparinux, or other strategies was used.

RESULTS

In total, 22,072 cases of primary joint arthroplasty were analyzed from 2014 to 2016. The national rate of less aggressive VTE prophylaxis strategies was 45.4%, while more aggressive strategies were used in 54.6% of patients. Significant regional differences in prophylactic strategy patterns exist between the 6 regions. The predominant less aggressive prophylaxis pattern was aspirin with sequential compression devises at 84.8% with 14.8% receiving aspirin alone. Use of less aggressive prophylaxis strategy was significantly associated with patients having no complications (95.5% vs 93.0%). Use of more aggressive prophylaxis patterns was associated with higher likelihood of mild thrombotic (0.9% vs 0.2%), mild bleeding (1.3% vs 0.4%), moderate thrombotic (1.2% vs 0.4%), moderate bleeding (2.7% vs 2.1%), severe thrombotic (0.1% vs 0.0%), severe bleeding events (1.2% vs 0.9%), infections (1.9% vs 1.3%), and death within 90 days (0.7% vs 0.3%). Similar results were found in subgroup analysis of total hip and knee arthroplasty patients.

CONCLUSION

It was not possible to ascertain the individual rationale for use of more aggressive VTE prophylaxis strategies; however, more aggressive strategies were associated with higher rates of bleeding and thrombotic complications. Less aggressive strategies were not associated with a higher rate of thrombosis.

LEVEL OF EVIDENCE

Therapeutic Level III.

DISCLAIMER

All views expressed in the study are the sole views of the authors and do not represent the views of the American Board of Orthopedic Surgery.

The Use of Aspirin for Prophylaxis Against Venous Thromboembolism Decreases Mortality Following Primary Total Joint Arthroplasty

BACKGROUND

The use of aspirin as prophylaxis against venous thromboembolism (VTE) following total joint arthroplasty (TJA) has increased in popularity; however, the potential cardioprotective effects of aspirin when administered as VTE prophylaxis remain unknown. The present study investigated the influence of VTE prophylaxis, including aspirin, on mortality following TJA.

METHODS

We retrospectively reviewed 31,133 patients who underwent primary TJA from 2000 to 2017. Patient demographics, body mass index, and comorbidities were obtained from an electronic chart query. Patients were allocated into 2 cohorts on the basis of the VTE prophylaxis administered: aspirin (25.9%, 8,061 patients) and non-aspirin (74.1%, 23,072 patients). Mortality was assessed with use of an institutional mortality database that is updated biannually. Univariate and multivariate regression analyses were performed.

RESULTS

The overall mortality rate was 0.2% and 0.6% at 30 days and 1 year after TJA, respectively. The use of aspirin was independently associated with lower risk of death at both 30 days (odds ratio [OR], 0.39; p = 0.020) and 1 year (OR, 0.51; p = 0.004). Patients in the non-aspirin cohort showed 3 times the risk of death at 30 days compared with the aspirin cohort (0.3% compared with 0.1%; p = 0.004), and twice the risk of death at 1 year (0.7% compared with 0.3%; p < 0.001). At 1 year, the primary cause of death in the non-aspirin group was cardiac-related (46 of 23,072, 0.20%). In the aspirin group, the rate of cardiac-related death was almost 5 times lower (3 of 8,061, 0.04%; p = 0.005). Risk factors for mortality at 1 year included higher age (p < 0.001), male sex (p = 0.020), history of congestive heart failure (p = 0.003), cerebrovascular disease (p < 0.001), malignancy (p < 0.001), and history of prior myocardial infarction (p < 0.001).

CONCLUSIONS

The present study demonstrates that the use of aspirin as prophylaxis against VTE following TJA may reduce the risk of mortality. Given the numerous options available and permitted by the current guidelines, orthopaedic surgeons should be aware of the potential added benefits of aspirin when selecting a VTE-prophylactic agent.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Cost-Utility Analysis of Venous Thromboembolism Prophylaxis Strategies for People Undergoing Elective Total Hip and Total Knee Replacement Surgeries in the English National Health Service

Background: Major orthopedic surgery, such as elective total hip replacement (eTHR) and elective total knee replacement (eTKR), are associated with a higher risk of venous thromboembolism (VTE) than other surgical procedures. Little is known, however, about the cost-effectiveness of VTE prophylaxis strategies in people undergoing these procedures. Aim: The aim of this work was to assess the cost-effectiveness of these strategies from the English National Health Service perspective to inform NICE guideline (NG89) recommendations. Materials and Methods: Cost-utility analysis, using decision modeling, was undertaken to compare 15 VTE prophylaxis strategies for eTHR and 12 for eTKR, in addition to "no prophylaxis" strategy. The analysis complied with the NICE Reference Case. Structure and assumptions were agreed with the guideline committee. Incremental net monetary benefit (INMB) was calculated, vs. the model comparator (LMWH+ antiembolism stockings), at a threshold of £20,000/quality-adjusted life-year (QALY) gained. The model was run probabilistically. Deterministic sensitivity analyses (SAs) were undertaken to assess the robustness of the results. Results: The most cost-effective strategies were LMWH for 10 days followed by aspirin for 28 days (INMB = £530 [95% CI: -£784 to £1,103], probability of being most cost-effective = 72%) for eTHR, and foot pump (INMB = £353 [95% CI: -£101 to £665]; probability of being most cost-effective = 18%) for eTKR. There was considerable uncertainty regarding the cost-effectiveness ranking in the eTKR analysis. The results were robust to change in all SAs. Conclusions: For eTHR, LMWH (standard dose) for 10 days followed by aspirin for 28 days is the most cost-effective VTE prophylaxis strategy. For eTKR, the results are highly uncertain but foot pump appeared to be the most cost-effective strategy, followed closely by aspirin (low dose). Future research should focus on assessing cost-effectiveness of VTE prophylaxis in the eTKR population.

Pulmonary Embolism While on Aspirin for Venous Thromboembolism Prophylaxis After Total Knee Arthroplasty

A 62-year-old Caucasian man with past medical history significant for coronary artery disease, status post drug eluting stent to the left anterior descending artery 10 years prior, was admitted for elective total right knee arthroplasty. His intraoperative course was uneventful, and he was discharged on hospital day 2 on aspirin 325 mg twice daily for 6 weeks for venous thromboembolism (VTE) prophylaxis. Three weeks later the patient developed chest pain shortly after an approximately 1-hour flight and presented to a local emergency department where computed tomography angiogram showed pulmonary emboli involving segmental and subsegmental pulmonary arteries bilaterally. He was transitioned from aspirin 325 mg twice a day to rivaroxaban 15 mg twice daily for 21 days, with a plan to transition to 20 mg daily to complete a 3-month course. He returned to his primary care physician 6 days after discharge with questions about his current anticoagulation therapy as well as the regimen he was on prior to the pulmonary embolism. Two major organizations, The American Academy of Orthopedic Surgeons and The American College of Chest Physicians, provide recommendations for VTE prophylaxis, but they differ regarding the preferred pharmacologic modality and duration. Although the goal is to provide optimal patient care, lack of guideline consensus may lead to different postoperative recommendations. It is important for clinicians to discuss with their patients the pharmacologic options available for VTE prophylaxis, how organizations differ in their recommendations, and the limitations of these pharmacologic agents.

Aspirin or Rivaroxaban for VTE Prophylaxis after Hip or Knee Arthroplasty

BACKGROUND

Clinical trials and meta-analyses have suggested that aspirin may be effective for the prevention of venous thromboembolism (proximal deep-vein thrombosis or pulmonary embolism) after total hip or total knee arthroplasty, but comparisons with direct oral anticoagulants are lacking for prophylaxis beyond hospital discharge.

METHODS

We performed a multicenter, double-blind, randomized, controlled trial involving patients who were undergoing total hip or knee arthroplasty. All the patients received once-daily oral rivaroxaban (10 mg) until postoperative day 5 and then were randomly assigned to continue rivaroxaban or switch to aspirin (81 mg daily) for an additional 9 days after total knee arthroplasty or for 30 days after total hip arthroplasty. Patients were followed for 90 days for symptomatic venous thromboembolism (the primary effectiveness outcome) and bleeding complications, including major or clinically relevant nonmajor bleeding (the primary safety outcome).

RESULTS

A total of 3424 patients (1804 undergoing total hip arthroplasty and 1620 undergoing total knee arthroplasty) were enrolled in the trial. Venous thromboembolism occurred in 11 of 1707 patients (0.64%) in the aspirin group and in 12 of 1717 patients (0.70%) in the rivaroxaban group (difference, 0.06 percentage points; 95% confidence interval [CI], -0.55 to 0.66; P<0.001 for noninferiority and P=0.84 for superiority). Major bleeding complications occurred in 8 patients (0.47%) in the aspirin group and in 5 (0.29%) in the rivaroxaban group (difference, 0.18 percentage points; 95% CI, -0.65 to 0.29; P=0.42). Clinically important bleeding occurred in 22 patients (1.29%) in the aspirin group and in 17 (0.99%) in the rivaroxaban group (difference, 0.30 percentage points; 95% CI, -1.07 to 0.47; P=0.43).

CONCLUSIONS

Among patients who received 5 days of rivaroxaban prophylaxis after total hip or total knee arthroplasty, extended prophylaxis with aspirin was not significantly different from rivaroxaban in the prevention of symptomatic venous thromboembolism. (Funded by the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT01720108 .).

Aspirin and the prevention of venous thromboembolism following total joint arthroplasty: commonly asked questions

The number of arthroplasties being performed increases each year. Patients undergoing an arthroplasty are at risk of venous thromboembolism (VTE) and appropriate prophylaxis has been recommended. However, the optimal protocol and the best agent to minimise VTE under these circumstances are not known. Although many agents may be used, there is a difference in their efficacy and the risk of bleeding. Thus, the selection of a particular agent relies on the balance between the desire to minimise VTE and the attempt to reduce the risk of bleeding, with its undesirable, and occasionally fatal, consequences.

Acetylsalicylic acid (aspirin) is an agent for VTE prophylaxis following arthroplasty. Many studies have shown its efficacy in minimising VTE under these circumstances. It is inexpensive and well-tolerated, and its use does not require routine blood tests. It is also a ‘milder’ agent and unlikely to result in haematoma formation, which may increase both the risk of infection and the need for further surgery. Aspirin is also unlikely to result in persistent wound drainage, which has been shown to be associated with the use of agents such as low-molecular-weight heparin (LMWH) and other more aggressive agents.

The main objective of this review was to summarise the current evidence relating to the efficacy of aspirin as a VTE prophylaxis following arthroplasty, and to address some of the common questions about its use.

There is convincing evidence that, taking all factors into account, aspirin is an effective, inexpensive, and safe form of VTE following arthroplasty in patients without a major risk factor for VTE, such as previous VTE.

Cite this article: Bone Joint J 2017;99-B:1420–30.

Comparative Effectiveness and Safety of Drug Prophylaxis for Prevention of Venous Thromboembolism After Total Knee Arthroplasty

BACKGROUND

Rates of venous thromboembolism in contemporary studies of primary total knee arthroplasty (TKA) have been reported to be as high as 3.5%. Although drug prophylaxis is effective, the best option among these regimens is not well established. The purpose of this study was to evaluate the comparative effectiveness and safety of aspirin, low-molecular-weight heparin, synthetic pentasaccharide factor Xa inhibitors, and vitamin K antagonist.

METHODS

Data were from a US total joint replacement registry, with 30,499 patients receiving unilateral TKA from May 16, 2006, to December 31, 2013. Patients received either aspirin (324-325 mg daily), enoxaparin (40-60 mg daily), fondaparinux (2.5 mg daily), or warfarin (all doses) and were followed up 90 days postoperatively on several outcomes: deep vein thrombosis, pulmonary embolism, major bleeding, wound complications, infection, and death.

RESULTS

There was no evidence that fondaparinux, enoxaparin, or warfarin were superior to aspirin in the prevention of pulmonary embolism, deep vein thrombosis, or venous thromboembolism or that aspirin was safer than these alternatives. However, enoxaparin was found to be as safe as aspirin with respect to bleeding, and fondaparinux was as safe as aspirin for risk of wound complications.

CONCLUSION

Among TKA patients, we did not find evidence for decreased effectiveness or increased safety with use of aspirin, but enoxaparin had comparable safety to aspirin for bleeding and fondaparinux had comparable safety to aspirin for wound complications.

Risk-Stratified Venous Thromboembolism Prophylaxis After Total Joint Arthroplasty: Aspirin and Sequential Pneumatic Compression Devices vs Aggressive Chemoprophylaxis

BACKGROUND

Venous thromboembolism (VTE) is a major concern after total joint arthroplasty (TJA). We evaluated a risk-stratified prophylaxis protocol for patients undergoing TJA.

METHODS

A total of 2611 TJA patients were retrospectively studied. Patients treated with an aggressive VTE chemoprophylaxis protocol were compared with patients treated with a risk-stratified protocol utilizing aspirin and sequential pneumatic compression devices (SPCDs) for standard-risk patients and targeted anticoagulation for high-risk patients.

RESULTS

We found equivalence in terms of VTE prevention between the 2 cohorts. There was a decrease in adverse events and readmissions among the risk-stratified cohort, although this did not reach statistical significance. A statistically significant reduction in costs (P < .001) was experienced with the use of aspirin/SPCDs compared with aggressive anticoagulation agents within the risk-stratified cohort.

CONCLUSION

The use of aspirin/SPCDs in a risk-stratified TJA population is a safe and cost-effective method of VTE prophylaxis.

Systematic review of aspirin for thromboprophylaxis in modern elective total hip and knee arthroplasty

Aims

There is uncertainty regarding the optimal means of thromboprophylaxis following total hip and knee arthroplasty (THA, TKA). This systematic review presents the evidence for acetylsalicylic acid (aspirin) as a thromboprophylactic agent in THA and TKA and compares it with other chemoprophylactic agents.

Materials and Methods

A search of literature published between 2004 and 2014 was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A total of 13 studies were eligible for inclusion.

Results

Evidence from one good quality randomised controlled trial (RCT) showed no difference in rates of venous thrombo-embolism (VTE) in patients given aspirin or low molecular weight heparin (LMWH) following TKA. There was insufficient evidence from trials with moderate to severe risk of bias being present to suggest aspirin is more or less effective than LMWH, warfarin or dabigatran for the prevention of VTE in TKA or THA. Compared with aspirin, rates of asymptomatic deep vein thrombosis (DVT) in TKA may be reduced with rivaroxaban but insufficient evidence exists to demonstrate an effect on incidence of symptomatic DVT. Compared with aspirin there is evidence of more wound complications following THA and TKA with dabigatran and in TKA with rivaroxaban. Some studies highlighted concerns over bleeding complications and efficacy of aspirin.

Conclusion

The results suggest aspirin may be considered a suitable alternative to other thromboprophylactic agents following THA and TKA. Further investigation is required to fully evaluate the safety and efficacy of aspirin. Cite this article: Bone Joint J 2016;98-B:1056–61.

Fatal pulmonary embolism following elective total hip arthroplasty

Aims

The place of thromboprophylaxis in arthroplasty surgery remains controversial, with a challenging requirement to balance prevention of potentially fatal venous thrombo-embolism with minimising wound-related complications leading to deep infection. We compared the incidence of fatal pulmonary embolism in patients undergoing elective primary total hip arthroplasty (THA) between those receiving aspirin, warfarin and low molecular weight heparin (LMWH) for the chemical component of a multi-modal thromboprophylaxis regime.

Patients and Methods

A prospective audit database was used to identify patients who had died within 42 and 90 days of surgery respectively between April 2000 and December 2012. A case note review was performed to ascertain the causes of death.

Results

During this period 7983 THAs were performed. The rate of mortality was 0.43% and 0.58% at 42 and 90 days respectively. The groups comprised 1571 patients (19.7%) on warfarin, 1838 (23.0%) on LMWH and 4574 (57.3%) on aspirin. The 90-day mortality for these three groups was 0.38%, 1.09% and 0.43% respectively. The higher mortality rate for LMWH was significant (p < 0.05). There were six fatal pulmonary emboli (PEs) (0.08%). A total of three occurred within 42 days, all in the LMWH group. A total of three occurred between 42 and 90 days; one on warfarin, two on LMWH. The leading causes of death in all three groups were lower respiratory tract infections and myocardial infarction.

Conclusion

We confirmed that fatal PE following elective THA with a multi-modal prophylaxis regime is rare. We further found that LMWH conferred no benefit over aspirin in this context, and is associated with a higher all-cause rate of mortality. Take home message: This study proposes that aspirin may be an appropriate thromboprophylaxis agent when used as part of a multi-modal regimen, suggesting current guidelines should be reviewed. Cite this article: Bone Joint J 2016;98-B:585–8.

Risk factors for venous thromboembolism of total hip arthroplasty and total knee arthroplasty: a systematic review of evidences in ten years

Background

Risk factors for venous thromboembolism (VTE) of total joint arthroplasty (TJA) have been examined by many studies. A comprehensive systematic review of recent findings of high evidence level in this topic is needed.

Methods

We conducted a PubMed search for papers published between 2003 and 2013 that provided level-I and level-II evidences on risk factors for VTE of TJA. For each potential factors examined in at least three papers, we summarize the the number of the papers and confirmed the direction of statistically significant associations, e.g. “risk factor” “protective factor” or “controversial factor”.

Results

Fifty-four papers were included in the systematic review. Risk factors found to be associated with VTE of both total hip arthroplasty and total knee arthroplasty included older age, female sex, higher BMI, bilateral surgery, surgery time > 2 hours. VTE history was found as a VTE risk factor of THA but an controversial factor of TKA. Cemented fixation as compared to cementless fixation was found as a risk factor for VTE only of TKA. TKA surgery itself was confirmed as a VTE risk factor compared with THA surgery.

Conclusions

This systematic review of high level evidences published in recent ten years identified a range of potential factors associated with VTE risk of total joint arthroplasty. These results can provide informations in this topic for doctors, patients and researchers.

Prevention of venous thromboembolic events following femoroacetabular osteoplasty: aspirin is enough for most

BACKGROUND

As hip-preservation surgery is performed in a particularly young and active group of patients, the knowledge accrued in the fields of hip arthroplasty and hip fracture care regarding postoperative thromboprophylaxis cannot be extrapolated to this patient population. Recommendations based on the evidence for each particular surgical procedure and population is desirable. For these reasons, the purpose of our study is to describe the rate of clinically relevant venous thromboembolism (VTE) and anticoagulation-related complications observed in patients undergoing hip-preservation surgery through mini-open femoracetabular osteoplasty (FAO) with a formal postoperative thromboprophylaxis protocol of aspirin dosing.

METHODS

A prospective case series of 407 consecutive FAO procedures in 375 patients of mean age 34.5 ± 11.1 years (range 15-62 years) were followed six weeks post operatively to document the presence of clinically relevant VTE as well as major bleeding events, as defined by the most recent American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. All patients were given aspirin 325 mg by mouth daily for two to four weeks.

RESULTS

There was one case of distal DVT in a 31-year-old male with no specific risk factors. No cases of pulmonary embolism were observed. There were no major bleeding events or reoperations due to postsurgical haematoma. There were no deaths. The crude incidence of clinically relevant VTE was 1 per 407 procedures (0.25%).

CONCLUSION

Aspirin is a safe and effective modality to provide thromboprophylaxis in patients undergoing hip-preservation surgery. The rate of VTE that we observed is, thus far, the lowest in comparison to other published series of hip preservation surgery that specifically focused on this complication.

Evidence-base for aspirin as venous thromboembolic prophylaxis following joint replacement

The National Institute for Health and Clinical Excellence (NICE) has thus far relied on historical data and predominantly industry-sponsored trials to provide evidence for venous thromboembolic (VTE) prophylaxis in joint replacement patients. We argue that the NICE guidelines may be reliant on assumptions that are in need of revision. Following the publication of large scale, independent observational studies showing little difference between low-molecular-weight heparins and aspirin, and recent changes to the guidance provided by other international bodies, should NICE reconsider their recommendations?

Cite this article: Bone Joint Res 2014;3:146–9.

Venous Thromboembolism (VTE) Prophylaxis for Hip and Knee Arthroplasty: Changing Trends

Venous thromboembolism (VTE) has been identified as an immediate threat to patients undergoing major orthopedic procedures such as total hip arthroplasty (THA) and total knee arthroplasty (TKA). Given the known dangers of VTE, arthroplasty surgeons are sensitive to the need for VTE thromboprophylaxis. However, the modalities of thromboprophylaxis used to minimize the risks to patients have been variable. Clinical practice guidelines have been published by several professional organizations, while some hospitals have established their own protocols. The 2 most popular guidelines are those published by the Academy of Orthopaedic Surgeons (AAOS) and American College of Chest Physicians (ACCP), both from North America. Prior to 2012, these recommendations varied depending on underlying definitions, methodology, and goals of the 2 groups. For the first time, both groups have similar recommendations that focus on minimizing symptomatic VTE and bleeding complications. The key to determining the appropriate chemoprophylaxis for patients is to balance efficacy of a prophylactic agent, while being safe in regards to bleeding complications. However, a multimodal approach that focuses on early postoperative mobilization and the use of mechanical prophylaxis, in addition to chemoprophylaxis, is essential.

Use of aspirin for the prevention of lower extremity deep venous thrombosis

Whereas aspirin is recommended and widely used to prevent arterial thrombosis, its role in the prevention of deep venous thrombosis is not well defined. Aspirin is well accepted, easy to manage with few risks and low cost, and thus ideal for thromboprophylaxis if evidence shows it is effective. Recent guidelines and large studies were reviewed. Recent guidelines include aspirin as an acceptable thromboprophylactic agent after hip and knee orthopedic surgery despite continued publication of underpowered and contradictory studies. Two large randomized controlled trials pooled together suggest that low-dose (100 mg) aspirin is a reasonable alternative to prevent recurrence of venous thromboembolism (VTE) in patients who have been treated for a first episode of unprovoked VTE. We suggest that the current practice using aspirin to prevent thromboembolism include cautious discussion of the benefits and risks of this agent before use in a patient until precise clarification of dosage and treatment length is available. Despite inclusion of aspirin in the guidelines for orthopedic surgery, there is little evidence to support its use for primary prevention of VTE. Until definitive unbiased trials are published, we suggest that aspirin remain a realistic option to use for secondary prevention of VTE, especially compared with the option of using no prophylaxis.