Safety and efficacy of new oral anticoagulants and low-molecular-weight heparins compared with aspirin in patients undergoing total knee and hip replacements

Prevention of venous thromboembolism with aspirin following knee surgery: A systematic review and meta-analysis

Venous thromboembolism (VTE) is a well-known complication following orthopaedic surgery. The incidence of this complication has decreased substantially since the introduction of routine thromboprophylaxis. However, concerns have been raised about increased bleeding complications caused by aggressive thromboprophylaxis.Attention has grown for aspirin as a safer thromboprophylactic agent following orthopaedic surgery.A systematic review using MEDLINE, Embase and Web of Science databases was undertaken to compare the effectiveness of aspirin prophylaxis following knee surgery with the current standard prophylactic agents (low molecular weight heparin [LMWH], vitamin K antagonists and factor Xa inhibitors).No significant difference in effectiveness of VTE prevention was found between aspirin, LMWH and warfarin. Factor Xa inhibitors were more effective, but increased bleeding complications were reported.As evidence is limited and of low quality with substantial heterogeneity, further research with high-quality, adequately powered trials is needed. Cite this article: EFORT Open Rev 2021;6:892-904. DOI: 10.1302/2058-5241.6.200120.

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.

Non-Inferiority of Aspirin for Venous Thromboembolism Prophylaxis After Hip Arthroplasty in a Statewide Registry

BACKGROUND

Uncertainty remains surrounding the use of aspirin as a sole chemoprophylactic agent to reduce the risk of venous thromboembolism (deep vein thrombosis or pulmonary embolism) and bleeding after primary total hip arthroplasty.

METHODS

We performed a non-inferiority analysis of a retrospective cohort of patients undergoing total hip arthroplasty from April 1, 2013 to December 31, 2018. Cases were retrieved from the Michigan Arthroplasty Registry Collaborative Quality Initiative database and performed by 355 surgeons at 61 hospitals throughout Michigan. Surgical setting ranged from small community hospitals to large academic and non-academic centers. The primary outcomes were post-operative venous thromboembolism event or death and bleeding event.

RESULTS

Of the 59,747 patients included, 32,878 (55.03%) were female, and the mean age was 64.5. A total of 462 (0.77%) composite venous thromboembolism events occurred. There were 221 (0.71%) and 129 (0.80%) venous thromboembolism events in patients receiving aspirin only and anticoagulants only, respectively. Aspirin was non-inferior to anticoagulants for composite venous thromboembolism events (odds ratio 0.99, 95% confidence interval 0.79-1.26, P < .001). Bleeding events occurred in 767 (1.28%) patients, with 304 (0.97%) and 281 (1.74%) bleeding events in patients receiving aspirin only and anticoagulants only, respectively. Aspirin was non-inferior to anticoagulants for bleeding events (odds ratio 0.62, 95% confidence interval 0.52-0.74, P < .001).

CONCLUSION

Aspirin is not inferior to other anticoagulants as pharmacologic venous thromboembolism prophylaxis with regards to post-operative risk of venous thromboembolism or bleeding. Sole use of aspirin for venous thromboembolism prophylaxis after total hip arthroplasty should be considered in the appropriate patient.

The Association Between Clopidogrel and Gastrointestinal Bleeding After Primary Total Joint Arthroplasty

Background

Anticoagulation after total joint arthroplasty has been demonstrated to reduce venous thromboembolism. However, anticoagulation can lead to adverse bleeding events. The purpose of this study was to assess if an association exists between specific anticoagulation modalities, such as clopidogrel, and postoperative gastrointestinal (GI) bleeding.

Methods

A prospective cohort of Medicare patients undergoing total joint arthroplasty from 2017 to 2019 (3535 patients) was retrospectively reviewed. The baseline characteristics and anticoagulation methods were compared between the “GI bleed” cohort and the “non-GI bleed cohort.” Independent t-tests were conducted for continuous variables, while chi-squared analysis was conducted for dichotomous variables.

Results

Thirteen patients (0.42%) sustained a postoperative complication of a GI bleed. The mean age for patients sustaining a GI bleed was 69.23 years compared with 72.30 years for the non-GI bleed cohort (P = .11). Six patients who sustained a GI bleed (46%) were on an anticoagulation therapy other than aspirin, and this trended toward significance (P = .09). Five patients who sustained a GI bleed (38%) were on clopidogrel (P < .01). Seven percent of patients on clopidogrel sustained a postoperative GI bleed (P < .01). None of the patients who sustained a postoperative GI bleed had a history of peptic ulcer disease.

Conclusion

Patients on clopidogrel in the acute perioperative period demonstrated a strong association with the complication of postoperative GI bleeding. Arthroplasty surgeons should be aware of this association to educate and monitor patients on clopidogrel therapy and to work as part of interdisciplinary teams to assess the risks vs benefits of perioperative clopidogrel.

PREVENTion of CLots in Orthopaedic Trauma (PREVENT CLOT): a randomised pragmatic trial protocol comparing aspirin versus low-molecular-weight heparin for blood clot prevention in orthopaedic trauma patients

INTRODUCTION

Patients who sustain orthopaedic trauma are at an increased risk of venous thromboembolism (VTE), including fatal pulmonary embolism (PE). Current guidelines recommend low-molecular-weight heparin (LMWH) for VTE prophylaxis in orthopaedic trauma patients. However, emerging literature in total joint arthroplasty patients suggests the potential clinical benefits of VTE prophylaxis with aspirin. The primary aim of this trial is to compare aspirin with LMWH as a thromboprophylaxis in fracture patients.

METHODS AND ANALYSIS

PREVENT CLOT is a multicentre, randomised, pragmatic trial that aims to enrol 12 200 adult patients admitted to 1 of 21 participating centres with an operative extremity fracture, or any pelvis or acetabular fracture. The primary outcome is all-cause mortality. We will evaluate non-inferiority by testing whether the intention-to-treat difference in the probability of dying within 90 days of randomisation between aspirin and LMWH is less than our non-inferiority margin of 0.75%. Secondary efficacy outcomes include cause-specific mortality, non-fatal PE and deep vein thrombosis. Safety outcomes include bleeding complications, wound complications and deep surgical site infections.

ETHICS AND DISSEMINATION

The PREVENT CLOT trial has been approved by the ethics board at the coordinating centre (Johns Hopkins Bloomberg School of Public Health) and all participating sites. Recruitment began in April 2017 and will continue through 2021. As both study medications are currently in clinical use for VTE prophylaxis for orthopaedic trauma patients, the findings of this trial can be easily adopted into clinical practice. The results of this large, patient-centred pragmatic trial will help guide treatment choices to prevent VTE in fracture patients.

TRIAL REGISTRATION NUMBER

NCT02984384.

Comparable efficacy of 100 mg aspirin twice daily and rivaroxaban for venous thromboembolism prophylaxis following primary total hip arthroplasty: a randomized controlled trial

Background:

Aspirin has demonstrated safety and efficacy for venous thromboembolism (VTE) prophylaxis following total hip arthroplasty (THA); however, inconsistent dose regimens have been reported in the literature. This study aimed to evaluate and compare the safety and efficacy of 100 mg aspirin twice daily with rivaroxaban in VTE prophylaxis following THA.

Methods:

Patients undergoing elective unilateral primary THA between January 2019 and January 2020 were prospectively enrolled in the study and randomly allocated to receive 5 weeks of VTE prophylaxis with either oral enteric-coated aspirin (100 mg twice daily) or rivaroxaban (10 mg once daily). Medication safety and efficacy were comprehensively evaluated through symptomatic VTE incidence, deep vein thrombosis (DVT) on Doppler ultrasonography, total blood loss (TBL), laboratory bloodwork, Harris hip score (HHS), post-operative recovery, and the incidence of other complications.

Results:

We included 70 patients in this study; 34 and 36 were allocated to receive aspirin and rivaroxaban prophylaxis, respectively. No cases of symptomatic VTE occurred in this study. The DVT rate on Doppler ultrasonography in the aspirin group was not significantly different from that in the rivaroxaban group (8.8% vs. 8.3%, χ² = 0.01, P = 0.91), confirming the non-inferiority of aspirin for DVT prophylaxis (χ² = 2.29, P = 0.01). The calculated TBL in the aspirin group (944.9 mL [658.5–1137.8 mL]) was similar to that in the rivaroxaban group (978.3 mL [747.4–1740.6mL]) (χ² = 1.55, P = 0.12). However, there were no significant inter-group differences in HHS at post-operative day (POD) 30 (Aspirin: 81.0 [78.8–83.0], Rivaroxaban: 81.0 [79.3–83.0], χ² = 0.43, P = 0.67) and POD 90 (Aspirin: 90.0 [89.0–92.0], Rivaroxaban: 91.5 [88.3–92.8], χ² = 0.77, P = 0.44), the incidence of bleeding events (2.9% vs. 8.3%, χ² = 0.96, P = 0.33), or gastrointestinal complications (2.9% vs. 5.6%, χ² = 1.13, P = 0.29).

Conclusion:

In terms of safety and efficacy, the prophylactic use of 100 mg aspirin twice daily was not statistically different from that of rivaroxaban in preventing VTE and reducing the risk of blood loss following elective primary THA. This supports the use of aspirin chemoprophylaxis following THA as a less expensive and more widely available option for future THAs.

Trial Registration:

Chictr.org, ChiCTR18000202894; http://www.chictr.org.cn/showproj.aspx?proj=33284

Low molecular weight heparin and aspirin for prevention of deep vein thrombosisafter orthopaedic surgery: a systematic review and meta-analysis

To comprehensively evaluate the clinical effects of low molecular weight heparin (LMWH) and aspirin for deep vein thrombosis (DVT) patients after orthopaedic surgery. Studies comparing LMWH and aspirin were retrieved in multiple databases. Review Manager 5.0 was adopted for meta-analysis, sensitivity analysis and bias analysis. Finally, 4460 patients in 6 studies were included, and the eligibility criteria were finally met. The meta-analysis suggested that there was significant difference between LMWH and aspirin groups in DVT (RR = 0.58, 95%CI [0.39, 0.88], P = 0.01; P for heterogeneity = 0.45, I² = 0%). Postoperative bleeding between the two groups showed no difference (RR = 2.20, 95%CI [0.48, 10.09], P = 0.31; P for heterogeneity = 0.79, I² = 0%) This study shows that LMWH is a more effective therapy than aspirin for patients with DVT after orthopaedic surgery.

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.

Stratifying Venous Thromboembolism Risk in Arthroplasty: Do High-Risk Patients Exist?

BACKGROUND

While there are many possible complications associated with total joint arthroplasty (TJA), venous thromboembolism (VTE) is both frequent and potentially severe. Despite this importance, there are inconsistent recommendations for prophylaxis based on patient risk factors.

METHODS

A predictive model was constructed to compare low-molecular-weight heparin(LMWH) and aspirin (ASA) for prevention of VTE-associated complications following TJA.The model used risks from prior prophylaxis studies to estimate the risk of developing a symptomatic deep vein thrombosis, pulmonary embolism, thrombocytopenia, and operative or nonoperative site bleeding. We also evaluated the progression to 4 possible final health states: postphlebitis syndrome, intracranial hemorrhage, death, or baseline health. Within published ranges, we selected assumptions that were favorable to LMWH such that these analyses represent a best case scenario for LMWH or an alternative more aggressive low-molecular-weight heparin alternative (LMWHA). Events and outcomes were assigned quality-adjusted life-year (QALY) losses according to prior studies to determine the effect on patients' outcomes for ASA and LMWHA prophylaxis.

RESULTS

Assessing VTE risk populations from 0.2% to 2% with life expectancies ranging from 5 to 40 years postoperatively, patients with a risk ratio less than 3.7 showed increased expected QALY with ASA compared to LMWHA. For patients with a baseline VTE risk of 1% and a 15 year life expectancy, a risk ratio of 13.4 was needed to identify patients that would benefit from LMWHA. With life expectancy increased to 30 years, the risk ratio needed to idetify these patients was 7.4.

CONCLUSION

Patients undergoing TJA should receive ASA chemoprophylaxis in nearly all situations, unless the patient has a significantly increased VTE risk compared to the baseline population and a long life expectancy.

Risk of Major Gastrointestinal Bleeding With New vs Conventional Oral Anticoagulants: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

There is controversy over whether use of non-vitamin K antagonist oral anticoagulants (NOACs) associates with increased risk of major gastrointestinal bleeding (GIB) compared with conventional therapies (such as vitamin K antagonists or anti-platelet agents). We performed a systematic review and meta-analysis of data from randomized controlled trials and high-quality real-world studies.

METHODS

We performed a systematic search of the MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov Website databases (through Oct 12, 2018) for randomized controlled trials and high-quality real-world studies that reported major GIB events in patients given NOACs or conventional therapy. Relative risks (RRs) for randomized controlled trials and adjusted hazard ratios (aHRs) for real-world studies were calculated separately using random-effects models.

RESULTS

We analyzed data from 43 randomized controlled trials (183,752 patients) and 41 real-world studies (1,879,428 patients). The pooled major rates of GIB for patients on NOACs (1.19%) vs conventional treatment (0.92%) did not differ significantly (RR from randomized controlled trials, 1.09; 95% CI, 0.91-1.31 and aHR from real-world studies, 1.02; 95% CI, 0.94-1.10; P_interaction=.52). Rivaroxaban, but not other NOACs, was associated with an increased risk for major GIB (RR from randomized controlled trials, 1.39; 95% CI, 1.17-1.65 and aHR from real-world studies, 1.14; 95% CI, 1.04-1.23; P_interaction = .06). Analyses of subgroups, such as patients with different indications, dosage, or follow-up time, did not significantly affect results. Meta-regression analysis failed to detect any potential confounding to impact the primacy outcome.

CONCLUSIONS

In a systematic review and meta-analysis of data from randomized controlled trials and real-world studies, we confirmed that there is no significant difference in risk of major GIB between patients receiving NOACs vs conventional treatment. Rivaroxaban users had a 39% increase in risk for major GIB.

Review of Therapeutic Options for the Prevention of VTE in Total Joint Arthroplasty

Hip and knee arthroplasty patients are at high risk of perioperative venous thromboembolic events (VTE). VTE has been well studied in this population and it is recommended that total joint arthroplasty recipients receive chemoprophylactic anticoagulation due to risk factors inherent to the surgical intervention. There are few concise resources for the orthopedic surgeon that summarize data regarding post-operative anticoagulation in the context of currently available therapeutic options and perioperative standards of practice. The periodic reexamination of literature is essential as conclusions drawn from studies predating perioperative protocols that include early mobilization and sequential compression devices as standards of practice in total joint arthroplasty are no longer generalizable to modern-day practice. We reviewed a large number of recently published research studies related to post-operative anticoagulation in total joint arthroplasty populations that received a high Level of Evidence grade. Current literature supports the use of oral aspirin regimens in place of more aggressive anticoagulants, particularly among low risk patients. Oral aspirin regimens appear to have the additional benefit of lower rates of bleeding and wound complications. Less consensus exists among high risk patients and more potent anticoagulants may be indicated. However, available evidence does not demonstrate clear superiority among current options, all of which may place patients at a higher risk of bleeding and wound complications. In this situation, chemoprophylactic selection should reflect specific patient needs and characteristics.

Gastrointestinal Complications Warranting Invasive Interventions Following Total Joint Arthroplasty

BACKGROUND

Gastrointestinal (GI) complications following total joint arthroplasty (TJA) are uncommon but can be associated with substantial morbidity and mortality. The current literature on GI complications that warrant invasive procedures after TJA is lacking. This study reviews the incidence and outcomes of GI complications after TJA that went on to require invasive procedures.

METHODS

All TJA patients at our institution between January 2012 and May 2018 who had GI complications requiring an invasive procedure within 30 days of TJA were identified and retrospectively chart reviewed. Descriptive statistics were used to evaluate these patients.

RESULTS

Of 19,090 TJAs in a 6-year period, 34 patients (0.18%) required invasive procedures for GI complications within 30 days of the index surgery. Twenty-two (64%) of the required procedures were endoscopy for suspected GI bleeding. Within this cohort, aspirin was the most common thromboprophylaxis used (63.6% of patients) and smoking was more prevalent (9.1% current smokers) (P = .28). Of the remaining 12 GI procedures required, 75% were exploratory laparotomies, 44.4% of which were performed for obstruction. Three (33.3%) of the exploratory laparotomy patients died during the study period.

CONCLUSION

GI complications necessitating surgical intervention after TJA are rare. Suspected GI bleeding is the most common indication for intervention and is typically managed endoscopically. Other complications, such as GI obstruction, often require more extensive intervention and open procedures. Though rare, GI complications following TJA can lead to detrimental outcomes, significant patient morbidity, and occasionally mortality; therefore, a heightened awareness of these complications is warranted.

Clinical, clinicopathologic, and gastrointestinal changes from administration of clopidogrel, prednisone, or combination in healthy dogs: A double-blind randomized trial

Background

Dogs with immune‐mediated disease often receive glucocorticoids with clopidogrel, but ulcerogenic effects of current protocols are unknown.

Hypothesis/Objectives

To compare gastrointestinal endoscopic findings among dogs administered clopidogrel, prednisone, and combination treatment.

Animals

Twenty‐four healthy research dogs.

Methods

Double‐blinded, placebo‐controlled randomized trial. Dogs received placebo, clopidogrel (2–3 mg/kg q24h), prednisone (2 mg/kg q24h), or prednisone with clopidogrel PO for 28 days. Attitude, food intake, vomiting, and fecal score were determined daily. Clinicopathologic testing was performed at baseline and on day 28. Gastrointestinal hemorrhages, erosions, and ulcers were numerated by 2 blinded investigators for endoscopies performed on days 0, 14, and 28, and endoscopic mucosal lesion scores were calculated. Results were compared using mixed model, split‐plot repeated measures ANOVAs and generalized estimating equation proportional odds models as appropriate. P < .05 was considered significant.

Results

Clinical signs of gastrointestinal bleeding were not noted. Endoscopic mucosal lesion scores differed significantly by group (F[3, 20] = 12.8, P < .001) and time (F[2, 40] = 8.3, P < .001). Posthoc analysis revealed higher lesion scores in the prednisone‐receiving groups (P ≤ .006 for each) and on day 14 (P ≤ .007 for each). Ulcers were identified in 4 dogs administered prednisone and 3 dogs administered prednisone/clopidogrel. Odds of having endoscopic mucosal lesion scores ≥4 were 7‐times higher for dogs in prednisone (95%CI 1.1, 43.0; P = .037) and prednisone‐clopidogrel (95%CI 1.1, 43.4; P = .037) groups than those in the placebo group.

Conclusions and Clinical Importance

Gastrointestinal bleeding and ulceration occur commonly in healthy dogs administered prednisone or prednisone/clopidogrel treatment, but not clopidogrel monotherapy. Though lesions are severe in many cases, they are not accompanied by clinical signs.

Clinical, clinicopathologic, and gastrointestinal changes from aspirin, prednisone, or combination treatment in healthy research dogs: A double-blind randomized trial

Background

Dogs with immune‐mediated disease are often coadministered glucocorticoids and aspirin, but ulcerogenic effects of current protocols are unknown.

Objectives

To compare gastrointestinal changes among dogs administered aspirin, prednisone, and combination treatment.

Animals

Twenty‐four healthy research dogs.

Methods

Double‐blinded, placebo‐controlled randomized trial of dogs administered placebo, aspirin (2 mg/kg q24h), prednisone (2 mg/kg q24h), or combination treatment PO for 28 days. Clinical signs were recorded daily, with laboratory work performed at baseline and day 28. Gastrointestinal mucosal hemorrhages, erosions, and ulcers were numerated for endoscopic studies performed on days 0, 14, and 28; endoscopic mucosal lesion scores were calculated. Results were compared using mixed model repeated‐measures analyses of variance and generalized estimating equation proportional odds models. P < .05 was considered significant.

Results

Gastric mucosal lesion scores differed by treatment‐by‐time (F[6, 40] = 4.4, P = .002), treatment (F[3, 20] = 7.1, P = .002), and time (F[2, 40] = 18.9, P < .001). Post hoc analysis revealed increased scores in the aspirin (day 14 only), prednisone, and prednisone/aspirin groups during treatment. Ulcers were identified on 14 studies, representing 10 dogs. Dogs receiving prednisone and prednisone/aspirin had 11.1 times (95% CI, 1.7‐73.6) and 31.5 times (95% CI, 3.5‐288.0) higher odds, respectively, of having endoscopic mucosal lesion scores ≥4 than dogs receiving placebo (P ≤ .01).

Conclusions and Clinical Importance

Gastrointestinal bleeding occurs commonly in dogs administered aspirin, prednisone, or prednisone/aspirin treatment, with higher lesion scores for dogs receiving combination treatment. Even severe lesions are not accompanied by clinical signs.

Clinical Effectiveness of Aspirin as Multimodal Thromboprophylaxis in Primary Total Hip and Knee Arthroplasty: A Review of 6078 Cases

BACKGROUND

Venous thromboembolism is a serious complication after total hip and knee arthroplasty. There is still no consensus regarding the best mode of thromboprophylaxis after lower limb arthroplasty. The aim of this study was to ascertain the efficacy, safety profile, and rate of adverse thromboembolic events of aspirin as extended out-of-hospital pharmacological anticoagulation for elective primary total hip and knee arthroplasty patients and whether these rates were comparable with published data for low-molecular-weight heparin (LMWH).

METHODS

Data were extracted from a prospective hospital-acquired thromboembolism database. The period of study was from January 1, 2013 to December 31, 2016, and a total of 6078 patients were treated with aspirin as extended thromboprophylaxis after primary total hip and knee arthroplasty.

RESULTS

The primary outcome measure of deep vein thrombosis and pulmonary embolism within 90 days postoperatively was 1.11%. The secondary outcome rates of wound infection, bleeding complications, readmission rate, and mortality were comparable to published results after LMWH use.

CONCLUSION

The results of this study clearly show that aspirin, as part of a multimodal thromboprophylactic regime, is an effective and safe regime in preventing venous thromboembolism with respect to risk of deep vein thrombosis or pulmonary embolism when compared to LMWH. It is a cheaper alternative to LMWH and has associated potential cost savings.

The Role of Aspirin and Unfractionated Heparin Combination Therapy Immediately After Total Hip and Knee Arthroplasty

Aspirin and unfractionated heparin (UH) are accepted options for venous thromboembolism (VTE) prophylaxis after total joint arthroplasty (TJA). The use of aspirin in addition to UH in preventing VTE after TJA has yet to be studied. The primary objective of this study was to determine VTE rates in patients receiving aspirin monotherapy and those receiving aspirin and UH combination therapy immediately following TJA. A TJA database from a single hospital system was retrospectively reviewed to identify all patients who underwent primary hip or knee arthroplasty from 2013 to 2016. Patients were divided into 3 groups based on postoperative VTE chemoprophylaxis: aspirin only, aspirin with 1 dose of UH, and aspirin with multiple doses of UH. There were 5350 patients included: 1024 aspirin only, 1695 aspirin plus 1 dose of UH, and 2631 aspirin plus multiple doses of UH. Deep venous thrombosis and pulmonary embolus rates did not vary significantly between groups (deep venous thrombosis: 1.1%, 0.9%, and 1.2%, respectively, P=.701; pulmonary embolus: 0.3%, 0.3%, and 0.2%, respectively, P=.894). Transfusion rates were significantly greater with 1 dose of UH (1.8%) and multiple doses of UH (4.3%) compared with aspirin only (0.9%) (P<.001). Additionally, the postoperative hemoglobin decreased significantly more postoperatively with the use of UH (P<.001). Aspirin and UH combination therapy did not decrease VTE incidence compared with aspirin monotherapy. Additionally, there was greater perioperative blood loss and an increased rate of blood transfusion in patients receiving UH. On the basis of these findings, the authors do not recommend UH as an additional mode of VTE prophylaxis when prescribing aspirin after elective TJA. [Orthopedics. 2018; 41(3):171-176.].

Haemostatic agent etamsylate in vitro and in vivo antagonizes anti-coagulant activity of heparin

Etamsylate is indicated for several anti-hemorrhagic indications in human and veterinary medicine. However, etamsylate has been shown to be effective only in specific hemorrhagic situations. Furthermore, mechanism of action of etamsylate is not known but recent research has shown its ability to inhibit heparin binding to several growth factors. We have evaluated the ability of etamsylate to interfere with the activities of heparin. Effects of etamsylate on vasodilatory activity of heparin were evaluated in rat aortic segments. Influence of etamsylate on anticoagulant activity of heparin was evaluated in vitro by determining prothrombin (PT) time and activated partial thromboplastin time (aPTT) in dog blood and in vivo by determining the interference of systemic and topical etamsylate on heparin-induced extension in bleeding time (BT) in rats. Despite failing to inhibit heparin-induced vasodilation of rat aorta, etamsylate significantly reduced the increase in aPTT caused by heparin (+30.4 ± 6.7% vs. +15.0 ± 2.8% for etamsylate at 100 µM, P < 0.05). Etamsylate also antagonized the anticoagulant effects driven by heparin in vivo since prevented the heparin-induced increase in BT when systemically (i.p.) administered (+94.6 ± 7.5% vs. +57.9 ± 9.2% at 10 mg/kg, P < 0.05, vs. +22.2 ± 16.8% at 30 mg/kg, P < 0.01). Additionally, topically applied etamsylate (125 mg/ml) significantly reduced heparin-induced BT increase (+102.5 ± 3.2% vs. +54.0 ± 5.8%, P < 0.01). These evidences show a pharmacological interference by etamsylate on heparin activities antagonizing pro-hemorrhagic effects of heparin in vitro and in vivo without inhibiting its vasodilatory properties. This ability could help to explain pharmacological effects of etamsylate and proposes its role for reversing pro-hemorrhagic states.

Aspirin for thromboprophylaxis in major orthopedic surgery: old drug, new tricks?

Major orthopedic surgery, mainly entailing hip fracture surgery, hip and knee arthroplasty, is associated with significant morbidity and mortality, which are especially attributable to the high risk of postoperative VTE. Such a considerable risk is mainly due to a procoagulant state sustained by several important mechanisms, including massive release of procoagulants from tissue and bone damage, blood vessel injury, reduced venous emptying, perioperative immobilization and cement polymerization, among others. The risk of VTE during and after major orthopedic surgery approximates 50-80% in patients with no thromboprophylaxis, and persists for up 3 to 6 months after surgery. The anticoagulant or antithrombotic armamentarium entails several anticoagulants such as heparin, coumarins, fondaparinux, and the recently developed DOACs inhibiting either activated factor Xa (i.e., rivaroxaban, apixaban, edoxaban) or thrombin (i.e., dabigatran), as well as aspirin, i.e., the oldest antiplatelet drug to be ever discovered and used in clinical practice. The current guidelines are not in complete agreement regarding the choice of the ideal thromboprophylaxis, since some consider aspirin, and some discourage it. Recent evidence seems to support the use of aspirin in selected situations and in selected protocols. Therefore, we believe that consideration should be made about increasing the use of this old but still effective drug for perioperative prophylaxis of VTE, especially in patients for whom the administration of DOACs may be challenging.