Impact of recent guideline changes on aspirin prescribing after knee arthroplasty

Aspirin as Venous Thromboembolism Prophylaxis in Arthroplasty Patients: An Analysis of Clinical Practice Guidelines Recommendations

BACKGROUND

Venous thromboembolism (VTE) is a recognized postoperative complication of hip or knee arthroplasty and incurs major morbidity and mortality. While anticoagulants are the mainstay of chemoprophylaxis, aspirin has recently emerged as a popular prophylactic agent. However, there is a lack of high-quality evidence comparing aspirin to anticoagulants as a method of VTE prophylaxis, and current guidelines are conflicting regarding using aspirin as first-line chemoprophylaxis. We aimed to investigate guideline characteristics that are associated with the recommendation for or against aspirin as a first-line agent.

METHODS

MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, and PubMed databases were searched from 1966 to January 2024 to identify clinical practice guidelines for VTE prophylaxis in adult hip or knee arthroplasty inpatients of average risk. The characteristics of the guideline were collected by 2 independent reviewers. Logistic regression was used to test the association between the recommendation for or against aspirin and guideline characteristics.

RESULTS

There were 26 guidelines published from February 2003 to September 2023 and included in this study. There were 5 guidelines that recommended aspirin and 11 guidelines that recommended against aspirin as first-line therapy. With a more recent year of publication, aspirin was more likely to be recommended (odds ratio 1.72, 95% confidence interval: 1.05 to 2.84) and less likely to be recommended against (odds ratio 0.61, 95% confidence interval: 0.41 to 0.90). No other variables, including the level of evidence used, the composition of the guideline working group, or the objective of the guideline, were associated with the recommendation for or against aspirin.

CONCLUSIONS

Guidelines were inconsistent in their recommendations regarding aspirin as first-line therapy as VTE prophylaxis in arthroplasty patients. Adequately powered randomized controlled trials using modern practices, such as early postoperative mobilization, are needed to better inform clinical practice guidelines.

An analysis of risk factors for venous thromboembolism in primary versus revision total joint arthroplasty

Background

One of the most serious complications after primary or revision lower extremity total joint arthroplasty (TJA) is venous thromboembolism disease (VTE). Identifying patients at high risk for VTE allows tailoring of prophylactic anticoagulation regimens to those most vulnerable. This study aimed to identify risk factors for VTE in primary and revision lower extremity TJA.

Methods

The Electronic Medical Record was queried from a single academic institution for all patients who underwent a lower extremity TJA between 2007 and 2020. Demographics, comorbid conditions, perioperative characteristics, and postoperative complications were identified. An Elastic Net Multiple Logistic Regression Model was used to assess 49 covariates and predict those associated with a significant risk of VTE.

Results

We identified 4900 primary and revision total knee arthroplasty (TKA) and total hip arthroplasty (THA) patients. There was no significant difference between primary and revision THA. Primary TKA had a higher rate of VTE than revision TKA. Significant risk factors identified for VTE in THA patients include histories of deep vein thrombosis (DVT), pulmonary embolism (PE), metastatic tumors, hemiplegia, and Hispanic ethnicity. Risk factors for VTE in TKA patients include histories of DVT, PE, metastatic tumors, and postoperative warfarin and heparin use. In all patients, age was a significant predictor of VTE risk.

Conclusion

Our work identifies many risk factors for VTE following TJA. While the increased rate of VTE in some populations may represent selection bias, it also highlights the incomplete understanding of the etiology and prevention of this complication in the joint arthroplasty population and requires further study.

Qualitative analysis of randomized controlled trials informing recommendations for venous thromboembolism prophylaxis after distal lower extremity injuries

Purpose:

The purpose of this study is to assess the quality of evidence to stratify recommendations for chemoprophylaxis following distal lower extremity trauma.

Methods:

Literature review identified primary studies investigating venous thromboembolism (VTE) chemoprophylaxis following traumatic injury distal to the knee. Inclusion criteria were randomized controlled trials in adult patients treated with and without operative intervention. Each primary study was assessed by the Consolidated Standards of Reporting Trials 2010 checklist and Modified Coleman methodology score.

Results:

Literature review resulted in 462 studies, of which 9 met inclusion and exclusion criteria. All studies included low molecular weight heparin as a treatment group with 2 (22%) also including a treatment group with a direct factor Xa inhibitor. Five studies (56%) used placebo as a control group. The mean Modified Coleman Methodology score was 63% (range 51%–72%), a categorical rating of Fair. The mean Consolidated Standards of Reporting Trials score was 78% (range 56%–97%). Most studies (89%) screened all asymptomatic subjects for deep venous thrombosis. Statistical significance in VTE incidence among prophylactic treatment groups was not achieved in 78%.

Conclusions:

Development of consensus for VTE prophylaxis recommendations following traumatic injury distal to the knee is complicated by heterogenous study populations, low incidence of VTE in study populations, and inconsistent definitions of clinically important VTE. Low molecular weight heparin is not consistently superior for preventing VTE. Chemoprophylaxis should be considered on an individual basis in the presence of additional risk factors, although an externally validated, evidence-based risk assessment tool does not currently exist.

Level of Evidence: IV, therapeutic

Current Guidelines and Practice Recommendations to Prevent Hospital-Acquired Conditions After Major Orthopaedic Surgeries

»

In 2016, a total of 48,771 hospital-acquired conditions (HACs) were reported in U.S. hospitals. These incidents resulted in an excess cost of >$2 billion, which translates to roughly $40,000 per patient with an HAC.

»

Current guidelines for the prevention of venous thromboembolism and surgical site infection consist primarily of antithrombotic prophylaxis and antiseptic technique, respectively.

»

The prevention of catheter-associated urinary tract infection (CA-UTI) and in-hospital falls and trauma is done best via education. In the case of CA-UTI, this consists of training staff about the indications for catheters and their timely removal when they are no longer necessary, and in the case of in-hospital falls and trauma, advising the patient and family about the patient's fall risk and communicating the fall risk to the health-care team.

»

Blood incompatibility is best prevented by implementation of a pretransfusion testing protocol. Pressure ulcers can be prevented via patient positioning, especially during surgery, and via postoperative skin checks.

Predictors and Outcomes of Postoperative Hemoglobin of <8 g/dL in Total Joint Arthroplasty

BACKGROUND

Restrictive transfusion practices have decreased transfusions in total joint arthroplasty (TJA). A hemoglobin threshold of <8 g/dL is commonly used. Predictors of this degree of postoperative anemia in TJA and its association with postoperative outcomes, independent of transfusions, remain unclear. We identified predictors of postoperative hemoglobin of <8 g/dL and outcomes with and without transfusion in TJA.

METHODS

Primary elective TJA cases performed with a multimodal blood management protocol from 2017 to 2018 were reviewed, identifying 1,583 cases. Preoperative and postoperative variables were compared between patients with postoperative hemoglobin of <8 and ≥8 g/dL. Logistic regression and receiver operating characteristic curves were used to assess predictors of postoperative hemoglobin of <8 g/dL.

RESULTS

Positive predictors of postoperative hemoglobin of <8 g/dL were preoperative hemoglobin level (odds ratio [OR] per 1.0-g/dL decrease, 3.0 [95% confidence interval (CI), 2.4 to 3.7]), total hip arthroplasty (OR compared with total knee arthroplasty, 2.1 [95% CI, 1.3 to 3.4]), and operative time (OR per 30-minute increase, 2.0 [95% CI, 1.6 to 2.6]). Negative predictors of postoperative hemoglobin of <8 g/dL were tranexamic acid use (OR, 0.42 [95% CI, 0.20 to 0.85]) and body mass index (OR per 1 kg/m2 above normal, 0.90 [95% CI, 0.86 to 0.94]). Preoperative hemoglobin levels of <12.4 g/dL in women and <13.4 g/dL in men best predicted postoperative hemoglobin of <8 g/dL. Overall, 5.2% of patients with postoperative hemoglobin of 7 to 8 g/dL and 95% of patients with postoperative hemoglobin of <7 g/dL received transfusions. Patients with postoperative hemoglobin of <8 g/dL had longer hospital stays (p < 0.001) and greater rates of emergency department visits or readmissions (p = 0.001) and acute kidney injury (p < 0.001). Among patients with postoperative hemoglobin of <8 g/dL, patients who received transfusions had a lower postoperative hemoglobin nadir (p < 0.001) and a longer hospital stay (p = 0.035) than patients who did not receive transfusions.

CONCLUSIONS

Postoperative hemoglobin of <8 g/dL after TJA was associated with worse outcomes, even for patients who do not receive transfusions. Optimizing preoperative hemoglobin levels may mitigate postoperative anemia and adverse outcomes.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Equivalent VTE rates after total joint arthroplasty using thromboprophylaxis with aspirin versus potent anticoagulants: retrospective analysis of 4562 cases across a diverse healthcare system

BACKGROUND

Guidelines support aspirin thromboprophylaxis for primary total hip and knee arthroplasty (THA and TKA) but supporting evidence has come from high volume centers and the practice remains controversial.

METHODS

We studied 4562 Medicare patients who underwent elective primary THA (1736, 38.1%) or TKA (2826, 61.9%) at 9 diverse hospitals. Thirty-day claims data were combined with data from the health system's electronic medical records to compare rates of venous thromboembolism (VTE) between patients who received prophylaxis with: (1) aspirin alone (47.3%), (2) a single, potent anticoagulant (29%), (3) antiplatelet agents other than aspirin or multiple anticoagulants (21.5%), or (4) low-dose subcutaneous unfractionated heparin or no anticoagulation (2.2%). Sub-analyses separately evaluating THA, TKA and cases from lower volume hospitals (n = 975) were performed.

RESULTS

The 30-day VTE incidence was 0.6% (29/4562). VTE rates were equal in patients receiving aspirin and those receiving a single potent anticoagulant (0.5% in both groups). Patients with VTE were significantly older than patients without VTE (mean 76.5 vs. 73.1 years, P = 0.04). VTE rate did not associate with sex or hospital case volume. On bivariate analysis considering age, aspirin did not associate with greater VTE risk compared to a single potent anticoagulant (OR = 2.1, CI = 0.7-6.3) with the numbers available. Odds of VTE were increased with use of subcutaneous heparin or no anticoagulant (OR = 6.4, CI = 1.2-35.6) and with multiple anticoagulants (OR = 3.6, CI = 1.1-11.2). THA and TKA demonstrated similar rates of VTE (0.5% vs. 0.7%, respectively, P = 0.43). Of 975 cases done at lower volume hospitals, 387 received aspirin, none of whom developed VTE.

CONCLUSIONS

This study provides further support for aspirin as an effective form of pharmacological VTE prophylaxis after total joint arthroplasty in the setting of a multi-modal regimen using 30-day outcomes. VTE occurred in 0.7% of primary joint arthroplasties. Aspirin prophylaxis did not associate with greater VTE risk compared to potent anticoagulants in the total population or at lower volume hospitals.

No Increased Risk of Venous Thromboembolism in High-Risk Patients Continuing Their Dose of 75 mg Aspirin Compared to Healthier Patients Given Low-Molecular-Weight Heparin

BACKGROUND

Optimum venous thromboembolism (VTE) prophylaxis for patients undergoing total hip or knee arthroplasty remains undefined. The purpose of this study is to compare complication rates among total joint arthroplasty patients using either low-dose aspirin (75 mg once daily) or low-molecular-weight heparin (LMWH; Fragmin/dalteparin 5000 U) for VTE prophylaxis.

METHODS

This is a prospective observational study. All total hip or knee arthroplasties from 2014 to 2020 were included. One thousand eighty-four patients already taking aspirin 75 mg as primary or secondary prophylaxis for cardiovascular disease continued their daily aspirin dose throughout their hospital stay and after discharge without any other kind of thromboprophylaxis. Five thousand ten patients not already taking aspirin were given LMWH for 12-14 days starting the day of surgery. Both groups consisted of patients undergoing either primary or revision total hip or knee arthroplasty. The aspirin group was older (73 ± 7.8 vs 66 ± 10.2 years, P < .01, 95% CI -7.6, -6.3) with more comorbidities but otherwise did not differ from the LMWH group. Outcome measures were recorded at 3-month follow-up and included the following complications: clinically deep venous thrombosis (DVT), pulmonary embolism (PE), deep infection, blood transfusion, and death.

RESULTS

The aspirin group had 0.28% DVT and 0.28% PE, and the LMWH group had 0.24% DVT and 0.16% PE (P = .42 and .74, respectively). No difference in deep infection, allogenic blood transfusion, or mortality was found.

CONCLUSION

No statistically significant difference in complication rates was found between aspirin 75 mg and LMWH used for VTE prophylaxis. Aspirin 75 mg daily is safe for VTE prophylaxis after total hip or knee arthroplasty.

Venous Thromboembolism After Pelvic Osteotomy in Adolescent Patients: A Database Study Characterizing Rates and Current Practices

BACKGROUND

Current risks and practices in medical prophylaxis of venous thromboembolism (VTE) after major elective lower extremity surgeries such as pelvic osteotomies have not been well-defined in the pediatric population. The purpose of this study was to (1) evaluate population rates of VTE in adolescents undergoing pelvic osteotomies, and (2) characterize current practices on types of VTE prophylaxis being utilized after pelvic osteotomies.

METHODS

The study evaluated the Pediatric Health Information System database between October 1, 2015 and January 1, 2020 for patients between 10 and 18 years of age meeting selected ICD-10 procedure and diagnosis codes relating to pelvic osteotomies. The rate of VTE was calculated within 90 days of index procedure. Types of pharmacologic prophylaxis were characterized. Continuous variables were compared with 2-sample t tests; proportions and categorical variables were compared with Fisher exact or χ2 tests, all with 2-tailed significance <0.05.

RESULTS

Of 1480 included patients, 9 were diagnosed with VTE within 90 days of surgery (VTE rate: 0.61%). Four of 9 (44.4%) had received pharmacologic prophylaxis postoperatively. There were no differences in baseline demographics or length of stay between patients that did or did not develop VTE (P>0.05). Overall, 52.0% received at least one form of pharmacologic prophylaxis postoperatively. The most common pharmacologic prophylaxis used was aspirin (47.6%), of which 64.4% received 81 mg dosing. There was no difference in VTE rates in those with or without prophylaxis (0.52% vs. 0.70%, P=0.75). However, those prescribed prophylaxis were significantly older (15.2±2.3 vs. 13.6±2.4 y, P<0.0001) and had a higher proportion of females (71.8% vs. 54.6%, P<0.01).

CONCLUSIONS

The overall rate of VTE in pediatric patients after pelvic osteotomies is non-negligible. There is heterogeneity in the type of anticoagulant utilized; however, VTE prophylaxis is most commonly prescribed in older adolescents and female patients. Guidelines for medical prevention of deep venous thrombosis and pulmonary embolism in the pediatric population are warranted after hip preservation surgery.

LEVEL OF EVIDENCE

Level IV, case series.

Unicompartmental knee arthroplasty and revision total knee arthroplasty have a lower risk of venous thromboembolism disease at 30 days than primary total knee arthroplasty

Background

While multiple studies have demonstrated a lower venous thromboembolism disease (VTED) risk for unicompartmental knee arthroplasty (UKA) compared to primary total knee arthroplasty (TKA), recent reports have shown that revision TKA also had a lower VTED risk compared to primary TKA, an unexpected finding because of its theoretical increased risk. Given the paucity of up-to-date comparative studies, our goal was to perform a high-powered VTED risk comparison study of UKA and revision TKA to primary TKA using recent data.

Methods

The National Surgical Quality Improvement Program (NSQIP) database was queried between 2011 and 2018, and we identified 213,234 patients for inclusion: 191,810 primary TKA, 9294 UKA, and 12,130 revision TKA. Demographics, medical comorbidities, and possible VTE risk factors were collected. Thirty-day outcomes, including deep vein thrombosis (DVT), pulmonary embolism (PE), and all-cause VTED were compared between knee arthroplasty types.

Results

On multivariate analysis, UKA was significantly associated with lower rates of DVT [OR 0.44 (0.31–0.61); P < 0.001], PE [OR 0.42 (0.28–0.65); P < 0.001], and all-cause VTED [OR 0.42 (0.32–0.55); P < 0.001] when compared to primary TKA. Revision TKA was significantly associated with lower rates of PE [OR 0.62 (0.47–0.83); P = 0.002], and all-cause VTED [OR 0.82 (0.70–0.98); P = 0.029] when compared to primary TKA.

Conclusions

Utilizing recent data from a nationwide patient cohort and controlling for confounding variables, our results showed that both revision TKA and UKA had a lower risk of VTED compared to primary TKA, corroborating the results of recent investigations. Additional prospective investigations are needed to explain this unexpected result.

Venous thromboprophylaxis after total hip arthroplasty: aspirin, warfarin, enoxaparin, or factor Xa inhibitors?

INTRODUCTION

Debate over the ideal agent for venous thromboembolism (VTE) prophylaxis after total hip arthroplasty (THA) has led to changes in prescribing trends of commonly used agents. We investigate variation in utilisation and the differences in VTE incidence and bleeding risk in primary THA after administration of aspirin, warfarin, enoxaparin, or factor Xa inhibitors.

METHODS

8829 patients were age/sex matched from a large database of primary THAs performed between 2007 and 2016. Utilisation was calculated using compound annual growth rate. Incidence of postoperative deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding-related complications, postoperative anaemia, and transfusion were identified at 2 weeks, 30 days, 6 weeks, and 90 days.

RESULTS

Aspirin use increased by 33%, enoxaparin by 7%, and factor Xa inhibitors by 31%. Warfarin use decreased by 1%. Factor Xa inhibitors (1.7%) and aspirin (1.7%) had the lowest incidence of DVT followed by enoxaparin (2.6%), and warfarin (3.7%) at 90 days. Factor Xa inhibitors (12%) and aspirin (12%) had the lowest incidence of blood transfusion followed by warfarin (15%) and enoxaparin (17%) at 90 days. There was no difference in incidence of blood transfusion or bleeding-related complications nor any detectable difference in symptomatic PE incidence.

CONCLUSIONS

The utilisation of aspirin and factor Xa inhibitors increased over time. Aspirin and factor Xa inhibitors provided improved DVT prophylaxis with lower rates of postoperative anaemia compared to enoxaparin and warfarin.

Have Venous Thromboembolism Rates Decreased in Total Hip and Knee Arthroplasty?

BACKGROUND

Venous thromboembolism (VTE) is a major cause of morbidity, mortality, and healthcare costs in arthroplasty patients. In an effort to reduce VTEs, numerous strategies and guidelines have been implemented, but their impact remains unclear. The purpose of this study is to compare annual trends in 30-day VTE, deep vein thrombosis (DVT), pulmonary embolism (PE), and all-cause mortality in (1) total hip arthroplasty (THA) and (2) total knee arthroplasty (TKA).

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database identified 363,530 patients who received a TKA or THA from 2008 to 2016. Bivariate analysis was performed to assess the association between the year in which surgery was performed and demographics and comorbidities. Bimodal multivariate logistic regression models for THA and TKA were developed for 2009-2016 using 2008 as a reference.

RESULTS

Overall incidence of VTE, DVT, PE, and mortality for THA were 0.6%, 0.4%, 0.3%, and 0.2%, respectively. Based off of multivariate regression VTE, DVT, PE, and mortality rates have shown no significant (P > .05) change from 2008 to 2016 in THA patients. Overall incidence of VTE, DVT, PE, and mortality for TKA were 1.4%, 0.9%, 0.6%, and 0.1%, respectively. Multivariate regression revealed reductions when compared to 2008 for VTEs and DVTs from 2009 to 2016 (P < .05) for TKA patients. A significant reduction in PEs (P = .002) was discovered for 2016, while no significant change was observed in mortality (P > .05).

CONCLUSION

Approximately 1 in 71 patient undergoing TKA, and 1 in 167 undergoing THA developed a VTE within 30 days after surgery. Our study demonstrated that VTE incidence rates have decreased in TKA, while remaining stable in THA over the past 8 years. Further research to determine the optimal prophylaxis algorithm that would allow for a personalized, efficacious, and safe thromboprophylaxis regimen is needed.

LEVEL OF EVIDENCE

III.

Association of Aspirin With Prevention of Venous Thromboembolism in Patients After Total Knee Arthroplasty Compared With Other Anticoagulants: A Noninferiority Analysis

Importance

There has been significant debate in the surgical and medical communities regarding the appropriateness of using aspirin alone for venous thromboembolism (VTE) prophylaxis following total knee arthroplasty (TKA).

Objective

To determine the acceptability of aspirin alone vs anticoagulant prophylaxis for reducing the risk of postoperative VTE in patients undergoing TKA.

Design, Setting, and Participants

Noninferiority study of a retrospective cohort of TKA cases submitted to the Michigan Arthroplasty Registry Collaborative Quality Initiative at 29 member hospitals, ranging from small community hospitals to large academic and nonacademic medical centers in Michigan. The study included 41 537 patients who underwent primary TKA between April 1, 2013, and October 31, 2015. Clinical events were monitored for 90 days after surgery. Data were analyzed between September and October 2016.

Exposures

The method of pharmacologic prophylaxis: neither aspirin nor anticoagulants for 668 patients (1.6%), aspirin only for 12 831 patients (30.9%), anticoagulant only (eg, low-molecular-weight heparin, warfarin, and Xa inhibitors) for 22 620 patients (54.5%), and both aspirin/anticoagulant for 5418 patients (13.0%). Most patients were also using intermittent pneumatic compression stockings.

Main Outcome and Measures

The primary composite outcome was the first occurrence of VTE or death. The noninferiority margin was specified as 0.3. The secondary outcome was bleeding events.

Results

Of the 41 537 patients, 14 966 were men (36%), and the mean age was 65.8 years. A VTE event occurred in 573 of 41 537 patients (1.38%); 32 of 668 (4.79%) who received no pharmacologic prophylaxis, 149 of 12 831 (1.16%) treated with aspirin alone, 321 of 22 620 (1.42%) with anticoagulation alone, and 71 of 5418 (1.31%) prescribed both aspirin and anticoagulation. Aspirin only was noninferior for the composite VTE outcome compared with those receiving other chemoprophylaxis (adjusted odds ratio, 0.85; 95% CI, 0.68-1.07, P for inferiority = .007). Bleeding occurred in 457 of 41 537 patients (1.10%), 10 of 668 (1.50%) without prophylaxis, 116 of 12 831 (0.90%) in the aspirin group, 258 of 22 620 (1.14%) with anticoagulation, and 73 of 5418 (1.35%) of those receiving both. Aspirin alone was also noninferior for bleeding complications (adjusted odds ratio, 0.80; 95% CI, 0.63-1.00, P for inferiority <.001).

Conclusions and Relevance

In this study of patients undergoing TKA, aspirin was not inferior to other anticoagulants in the postoperative rate of VTE or death. Aspirin alone may provide similar protection from postoperative VTE compared with other anticoagulation treatments.

Venous Thromboembolism Rates Did Not Decrease in Lower Extremity Revision Total Joint Arthroplasty From 2008 to 2016

BACKGROUND

In revision total knee arthroplasty (rTKA) and revision total hip arthroplasty (rTHA), venous thromboembolism (VTE) has been reported to be a relatively common and potentially serious complication. To mitigate this risk, strategies such as rapid recovery programs and thromboprophylaxis guidelines have been utilized. This study sought to identify the annual incidence and recent trends of VTE (defined as the presence of deep vein thrombosis [DVT] and/or pulmonary embolism [PE] in the same patient), DVT, PE, and mortality in the 30-day period after rTKA and rTHA.

METHODS

We identified 30,406 rTKA and rTHA patients from 2008 to 2016 using the National Surgical Quality Improvement Program database. Thirty-day incidences for VTE, DVT, PE, and mortality for each year and the overall study period were calculated. Bivariate and multivariate regressions were performed using patient demographics and comorbidities to assess trends in the outcomes of interest.

RESULTS

The overall incidences of 30-day VTE, DVT, PE, and mortality for rTKA were 1.2%, 0.9%, 0.4%, and 0.5%. Bivariate analysis revealed no significant change over the study period for VTE (P = .137), DVT (P = .406), PE (P = .121; 99% confidence interval 0.112-0.129), and mortality (P = .463). The incidences over the study period of VTE, DVT, PE, and mortality in rTHA were 1.0%, 0.7%, 0.4%, and 0.7%. Bivariate analysis revealed no changes in VTE (P = .393), DVT (P = .376), and PE (P = .602). However, bivariate analysis revealed significant decrease in mortality (P = .010) over the study period.

CONCLUSION

Within 30 days of surgery, approximately 1 in 83 rTKA patients and 1 in 100 rTHA patients experienced a VTE. Furthermore, the rates of VTE remained largely unchanged from 2008 to 2016. Further research regarding the optimal individualized prophylaxis algorithm in rTKA and rTHA is warranted to prevent this complication. This study represents the first investigation of thromboembolic events in rTHA and rTKA.

Aspirin Compared with Anticoagulation to Prevent Venous Thromboembolism After Knee or Hip Arthroplasty: a Large Retrospective Cohort Study

BACKGROUND

Although guidelines now allow the use of aspirin as an alternative to anticoagulants for venous thromboembolism prophylaxis after knee or hip arthroplasty, there is limited data on contemporary use and outcomes with aspirin.

OBJECTIVE

To describe the use of pharmacologic thromboprophylaxis and to assess venous thromboembolic risk with aspirin compared with anticoagulation after knee or hip arthroplasty.

DESIGN

Retrospective cohort study using data from the US MedAssets database.

PATIENTS

Adults with a principal discharge diagnosis of knee or hip arthroplasty between January 1, 2013, and December 31, 2014.

MAIN MEASURES

We identified charges for medications used for thromboprophylaxis within 7 days after the index surgery from billing records. The primary outcome was postoperative venous thromboembolism identified by International Classification of Diseases, 9th edition codes, from the index hospitalization, rehospitalization within 30 days, or during an outpatient visit within 90 days postoperatively. We compared postoperative thromboembolic risk in patients receiving aspirin-only and those receiving anticoagulants using propensity score-adjusted multivariable logistic regression models.

KEY RESULTS

We identified 74,234 patients with knee arthroplasty and 36,192 with hip arthroplasty who received pharmacologic thromboprophylaxis. Aspirin-only was used in 27.9% of all patients, while 24.2% and 24.1% received warfarin or enoxaparin as prophylactic monotherapy, respectively. Postoperative venous thromboembolism occurred in 495 (0.67%) patients undergoing knee arthroplasty and 145 (0.40%) undergoing hip arthroplasty. Aspirin-only was not related to increased odds of postoperative venous thromboembolism compared with anticoagulants in multivariable adjusted analyses (odds ratio [OR] 0.70; 95% confidence interval [CI], 0.56-0.87, and OR 0.93; 95% CI, 0.62-1.38 for knee or hip arthroplasty, respectively).

CONCLUSIONS

More than a fourth of all patients received aspirin as the sole antithrombotic agent after knee or hip arthroplasty. Postoperative thromboprophylaxis with aspirin-only was not associated with a higher risk of postoperative venous thromboembolism compared with anticoagulants after hip or knee arthroplasty.

Venous thromboembolism in plastic surgery: the current state of evidence in risk assessment and chemoprophylactic options

The application of venous thromboembolism (VTE) prophylaxis has been the topic of intense debate in plastic surgery. The overall incidence of VTE is low in plastic surgery patients as compared to other surgical subspecialties but may be higher in the inpatient rather than outpatient plastic surgery populations. The Caprini Risk Assessment Model is the most highly studied and validated tool to assess VTE risk in plastic surgery patients. However, the Caprini model lacks procedure-specific risk assessment and patient-specific risk factor calculations. Due to these limitations, such as the low incidence and the heterogeneous nature of the specialty, trials lacked the power to capture proof of benefit, except in the highest-risk inpatient population. The emerging use of aspirin and novel oral anticoagulants may provide an alternative, as noninferiority in terms of efficacy and safety has been demonstrated in other fields. In this review, the authors intend to summarize the current state of evidence for prevention and explore the modalities available for prophylaxis, including novel oral anticoagulants.

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.

Methods of sample size calculation in descriptive retrospective burden of illness studies

Background

Observational burden of illness studies are used in pharmacoepidemiology to address a variety of objectives, including contextualizing the current treatment setting, identifying important treatment gaps, and providing estimates to parameterize economic models. Methodologies such as retrospective chart review may be utilized in settings for which existing datasets are not available or do not include sufficient clinical detail. While specifying the number of charts to be extracted and/or determining whether the number that can feasibly extracted will be clinically meaningful is an important study design consideration, there is a lack of rigorous methods available for sample size calculation in this setting. The objective of this study was to develop recommended sample size calculations for use in such studies.

Methods

Calculations for identifying the optimal feasible sample size calculations were derived, for studies characterizing treatment patterns and medical costs, based on the ability to comprehensively observe treatments and maximize precision of resulting 95% confidence intervals. For cost outcomes, if the standard deviation is not known, the coefficient of variation cv can be used as an alternative. A case study of a chart review of advanced melanoma (MELODY) was used to characterize plausible values for cv in a real-world example.

Results

Across sample sizes, any treatment given with greater than 1% frequency has a high likelihood of being observed. For a sample of size 200, and a treatment given to 5% of the population, the precision of a 95% confidence interval (CI) is expected to be ±0.03. For cost outcomes, for the median cv value observed in the MELODY study (0.72), a sample size of approximately 200 would be required to generate a 95% CI precise to within ±10% of the mean.

Conclusion

This study presents a formal guidance on sample size calculations for retrospective burden of illness studies. The approach presented here is methodologically rigorous and designed for practical application in real-world retrospective chart review studies.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0657-9) contains supplementary material, which is available to authorized users.

Clinical Impact of Coagulation and Fibrinolysis Markers for Predicting Postoperative Venous Thromboembolism in Total Joint Arthroplasty Patients

One common complication after joint arthroplasty is venous thromboembolism (VTE). Therefore, it is essential to measure the changes in coagulation and fibrinolysis in order to predict VTE among patients who underwent joint arthroplasty. This study aimed to identify potential useful biomarkers for prognosing to VTE. This was a prospective cohort study enrolling 83 patients who underwent joint arthroplasty. The levels of d-dimer, thrombin-antithrombin complex (TAT), plasmin-α2-antiplasmin complex (PIC), soluble thrombomodulin, and tissue plasminogen activator inhibitor complex were measured on day 0 (before surgery) and days 1, 3, and 6 after surgery. Ultrasound examination was used to diagnose VTE on preoperative day 0 and postoperative day 6. A total of 35 patients developed VTE after surgery. Patients with VTE exhibited significantly higher levels of d-dimer and TAT on postoperative days 3 and 6 (all P < .05). The area under curves (AUC) of receiver operating characteristic (ROC) were 0.65 and 0.68 and 0.68 and 0.74 for d-dimer and TAT levels on postoperative days 3 and 6, respectively. The level of TAT/PIC ratio on postoperative day 6 was significantly increased among patients with VTE compared to non-VTE patients (P < .0001). In addition, the AUC of ROC, cutoff level, sensitivity, specificity, positive-predictive value, and negative-predictive value of TAT/PIC ratio were 0.78, 4.03 ng/TU, 97.14%, 33.33%, 51.52%, and 94.12%, respectively. The high sensitivity and negative predictive value of TAT/PIC ratio make it a potential prognostic index for diagnosing VTE during the early phase of postoperative joint arthroplasty.

Aspirin Alone Is Not Enough to Prevent Deep Venous Thrombosis After Total Joint Arthroplasty

Thromboembolic events after total joint arthroplasty are potentially devastating complications. This study evaluated the efficacy of 4 different anticoagulants in preventing deep venous thrombosis and pulmonary embolism after total joint arthroplasty. The demographics and anticoagulant use (warfarin, enoxaparin, and aspirin with and without outpatient mechanical pumps) for patients who underwent primary unilateral total joint arthroplasties performed by a single surgeon from January 2013 to October 2014 were retrospectively reviewed. All patients underwent lower extremity ultrasound at the 3-week postoperative visit. A total of 613 primary unilateral total joint arthroplasties met the study inclusion criteria. There were 288 primary total knee arthroplasties and 325 primary total hip arthroplasties. The patients were 62.2% female, having a mean age of 67.6±10.6 years and a mean body mass index of 30.2±5.9 kg/m². There were 119 patients in group 1 (aspirin alone), 40 patients in group 2 (aspirin plus pumps), 246 patients in group 3 (warfarin), and 208 patients in group 4 (enoxaparin). The overall 3-week symptomatic and asymptomatic deep venous thrombosis and symptomatic pulmonary embolism rates in the entire cohort were 5.7% and 0.3%, respectively. The venous thromboembolism rate was significantly affected by the anticoagulant of choice (P<.01). Compared with aspirin alone, warfarin decreased the risk of venous thromboembolism (P<.01). Increasing age led to increased risk of venous thromboembolism (P=.05). This study indicated that aspirin chemoprophylaxis alone was not as efficacious as warfarin and enoxaparin in preventing asymptomatic and symptomatic venous thromboembolism found during routine postoperative surveillance with lower extremity ultrasound. Aspirin alone may be inadequate and should be augmented with an outpatient mechanical pump as part of multimodal prophylaxis. [Orthopedics. 2019; 42(1):48-55.].

A Systematic Review on the Use of Aspirin in the Prevention of Deep Vein Thrombosis in Major Elective Lower Limb Orthopedic Surgery: An Update from the Past 3 Years

Introduction  Currently there are no consensuses in the national guidance on thromboprophylaxis following major elective lower limb surgery. Emerging clinical evidence suggests that aspirin could be just as effective as anticoagulants with a lower cost. The aim of this study was to provide an update based on literature of the past 3 years for the use of aspirin as thromboprophylaxis after knee and hip arthroplasty.

Materials and Methods  MEDLINE/EMBASE search was performed with appropriate terms for original articles from 2014 to 2017.

Results  Eight articles were found. Five articles concluded that aspirin was an effective prophylactic. The collation of results on the deep vein thrombosis rate involved 43,012 patients who were prescribed aspirin, of which 283 (0.66%) suffered from symptomatic deep vein thromboses. Aspirin was noted for its good side effect profile and cost effectiveness. It was noted that anticoagulants had a higher rate of complications, including bleeding and wound-oozing.

Conclusion  Aspirin is an effective and safe prophylactic against deep vein thrombosis following major elective lower limb arthroplasty surgery.

Venous Thromboembolism Prophylaxis After TKA: Aspirin, Warfarin, Enoxaparin, or Factor Xa Inhibitors?

BACKGROUND

There is considerable debate regarding the ideal agent for venous thromboembolism (VTE) prophylaxis after TKA. Numerous studies and meta-analyses have yet to provide a clear answer and often omit one or more of the commonly used agents such as aspirin, warfarin, enoxaparin, and factor Xa inhibitors.

QUESTIONS/PURPOSES

Using a large database analysis, we asked: (1) What are the differences in VTE incidence in primary TKA after administration of aspirin, warfarin, enoxaparin, or factor Xa inhibitors? (2) What are the differences in bleeding risk among these four agents? (3) How has use of these agents changed with time?

METHODS

We queried a combined Humana and Medicare database between 2007 and Quarter 1 of 2016, and identified all primary TKAs performed using ICD-9 and Current Procedural Terminology codes. All patients who had any form of antiplatelet or anticoagulation prescribed within 1 year before TKA were excluded from our study cohort. We then identified patients who had either aspirin, warfarin, enoxaparin, or factor Xa inhibitors prescribed within 2 weeks of primary TKA. Each cohort was matched by age and sex. Elixhauser comorbidities and Charlson Comorbidity Index for each group were calculated. We identified 1016 patients with aspirin, and age- and sex-matched 6096 patients with enoxaparin, 6096 patients with warfarin, and 5080 patients with factor Xa inhibitors. Using ICD-9 codes, with the understanding that patients at greater risk may have had more-attentive surveillance, the incidence of postoperative deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding-related complications (bleeding requiring surgical intervention, hemorrhage, hematoma, hemarthrosis), postoperative anemia, and transfusion were identified at 2 weeks, 30 days, 6 weeks, and 90 days postoperatively. A four-way chi-squared test was used to determine statistical significance. Utilization was calculated using compound annual growth rate.

RESULTS

There was a difference in the incidence of DVT at 90 days (p < 0.01). Factor Xa inhibitors (2.9%) had the lowest incidence of DVT followed by aspirin (3.0%) and enoxaparin (3.5%), and warfarin (4.8%). There was a difference in the incidence of PE at 90 days (p < 0.01). Factor Xa inhibitors (0.9%) had the lowest incidence of PE followed by enoxaparin (1.1%), aspirin (1.2%), and warfarin (1.6%). There was a difference in the incidence of postoperative anemia at 90 days (p < 0.01). Aspirin (19%) had the lowest incidence of postoperative anemia followed by warfarin (22%), enoxaparin (23%), and factor Xa inhibitors (23%). There was a difference in the incidence of a blood transfusion at 90 days (p < 0.01). Aspirin (7%) had the lowest incidence of a blood transfusion followed by factor Xa inhibitors (9%), warfarin (12%), and enoxaparin (13%). There were no differences in bleeding-related complications (p = 0.81) between the groups. Aspirin use increased at a compound annual growth rate of 30%, enoxaparin at 3%, and factor Xa inhibitors at 43%, while warfarin use decreased at a compound annual growth rate of -3%.

CONCLUSIONS

Factor Xa inhibitors had the highest growth in utilization during our study period, followed by aspirin, when compared with enoxaparin and warfarin. When selected for the right patient, factor Xa inhibitors provided improved VTE prophylaxis compared with enoxaparin and warfarin, with a lower rate of blood transfusion. Aspirin provided comparable VTE prophylaxis compared with factor Xa inhibitors with improved VTE prophylaxis compared with enoxaparin and warfarin with the lowest risk of bleeding.

LEVEL OF EVIDENCE

Level III, therapeutic study.