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

In-line NIR coupled with machine learning to predict mechanical properties and dissolution profile of PLA-Aspirin

In the production of polymeric drug delivery devices, dissolution profile and mechanical properties of the drug loaded polymeric matrix are considered important Critical Quality Attributes (CQA) for quality assurance. However, currently the industry relies on offline testing methods which are destructive, slow, labour intensive, and costly. In this work, a real-time method for predicting these CQAs in a Hot Melt Extrusion (HME) process is explored using in-line NIR and temperature sensors together with Machine Learning (ML) algorithms. The mechanical and drug dissolution properties were found to vary significantly with changes in processing conditions, highlighting that real-time methods to accurately predict product properties are highly desirable for process monitoring and optimisation. Nonlinear ML methods including Random Forest (RF), K-Nearest Neighbours (KNN) and Recursive Feature Elimination with RF (RFE-RF) outperformed commonly used linear machine learning methods. For the prediction of tensile strength RFE-RF and KNN achieved R 2 values 98% and 99%, respectively. For the prediction of drug dissolution, two time points were considered with drug release at t = 6 h as a measure of the extent of burst release, and t = 96 h as a measure of sustained release. KNN and RFE-RF achieved R 2 values of 97% and 96%, respectively in predicting the drug release at t = 96 h. This work for the first time reports the prediction of drug dissolution and mechanical properties of drug loaded polymer product from in-line data collected during the HME process.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42252-024-00063-5.

Screening and Prophylaxis for Venous Thromboembolism in Pediatric Surgery: A Systematic Review

OBJECTIVE

The American Pediatric Surgical Association Outcomes and Evidence-Based Practice Committee conducted a systematic review to describe the epidemiology of venous thromboembolism (VTE) in pediatric surgical and trauma patients and develop recommendations for screening and prophylaxis.

METHODS

The Medline (Ovid), Embase, Cochrane, and Web of Science databases were queried from January 2000 through December 2021. Search terms addressed the following topics: incidence, ultrasound screening, and mechanical and pharmacologic prophylaxis. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were followed. Consensus recommendations were derived based on the best available literature.

RESULTS

One hundred twenty-four studies were included. The incidence of VTE in pediatric surgical populations is 0.29% (Range = 0.1%-0.48%) and directly correlates with surgery type, transfusion, prolonged anesthesia, malignancy, congenital heart disease, inflammatory bowel disease, infection, and female sex. The incidence of VTE in pediatric trauma populations is 0.25% (Range = 0.1%-0.8%) and directly correlates with injury severity, major surgery, central line placement, body mass index, spinal cord injury, and length-of-stay. Routine ultrasound screening for VTE is not recommended. Consider sequential compression devices in at-risk nonmobile, pediatric surgical patients when an appropriate sized device is available. Consider mechanical prophylaxis alone or with pharmacologic prophylaxis in adolescents >15 y and post-pubertal children <15 y with injury severity scores >25. When utilizing pharmacologic prophylaxis, low molecular weight heparin is superior to unfractionated heparin.

CONCLUSIONS

While VTE remains an infrequent complication in children, consideration of mechanical and pharmacologic prophylaxis is appropriate in certain populations.

TYPE OF STUDY

Systematic Review of level 2-4 studies.

LEVEL OF EVIDENCE

Level 3-4.

Immunothrombosis versus thrombo-inflammation: platelets in cerebrovascular complications

A State-of-the Art lecture titled "Thrombo-Neuroinflammatory Disease" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. First, we would like to advocate for discrimination between immunothrombosis and thrombo-inflammation, as immunothrombosis describes an overshooting inflammatory reaction that results in detrimental thrombotic activity. In contrast, thrombo-inflammation describes the interplay of platelets and coagulation with the immunovascular system, resulting in the recruitment of immune cells and loss of barrier function (hence, hallmarks of inflammation). Both processes can be observed in the brain, with cerebral venous thrombosis being a prime example of immunothrombosis, while infarct progression in response to ischemic stroke is a paradigmatic example of thrombo-inflammation. Here, we review the pathomechanisms underlying cerebral venous thrombosis and ischemic stroke from a platelet-centric perspective and discuss translational implications. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.

Acetylsalicylic Acid is Not Associated With Improved Clinical Outcomes After Microsurgical Breast Reconstruction

INTRODUCTION

Microvascular thrombosis with resultant flap loss remains a devastating complication in autologous breast reconstruction. While acetylsalicylic acid (ASA) for prevention of microvascular thrombosis is commonly administered postoperatively, clinical evidence supporting this practice remains insufficient. Here, we investigate the association of postoperative ASA administration with differences in clinical outcomes following microsurgical breast reconstruction.

METHODS

A prospectively maintained database was queried to identify patients who had undergone microsurgical breast reconstruction. Patients were categorized based on whether they had received postoperative ASA for 30 d (Group 1) or had not received ASA (Group 2). Patient demographics, reconstructive outcomes, complications, and transfusion requirements were retrieved.

RESULTS

One hundred thirty six patients with a mean age of 49.5 y and a mean body mass index of 28.5 kg/m² who had undergone a total of 216 microsurgical breast reconstructions were included. No significant differences were noted with regard to patient demographics with the exceptions of increased rates of neoadjuvant chemotherapy and delayed reconstruction in Group 1. There were no significant differences in the rates of postoperative complications including breast hematoma, mastectomy skin flap necrosis, partial flap necrosis, seroma, and deep venous thrombosis between patients who did or did not receive ASA postoperatively. Similarly, no difference was noted regarding postoperative blood transfusion rates (Group 1: 9.9% versus Group 2: 9.1%; P = 0.78). Finally, patients in Group 1 had significantly longer hospital stays (Q1 = 4, median = 4.5, Q3 = 5).

CONCLUSIONS

Postoperative ASA administration is not associated with improved postoperative clinical outcomes. The use of ASA routinely after autologous breast reconstruction does not appear to be a necessity in practice.

Platelets and Their Role in Hemostasis and Thrombosis-From Physiology to Pathophysiology and Therapeutic Implications

Hemostasis is a physiological process critical for survival. Meanwhile, thrombosis is amongst the leading causes of death worldwide, making antithrombotic therapy one of the most crucial aspects of modern medicine. Although antithrombotic therapy has progressed tremendously over the years, it remains far from ideal, and this is mainly due to the incomplete understanding of the exceptionally complex structural and functional properties of platelets. However, advances in biochemistry, molecular biology, and the advent of 'omics' continue to provide crucial information for our understanding of the complex structure and function of platelets, their interactions with the coagulation system, and their role in hemostasis and thrombosis. In this review, we provide a comprehensive view of the complex role that platelets play in hemostasis and thrombosis, and we discuss the major clinical implications of these fundamental blood components, with a focus on hemostatic platelet-related disorders and existing and emerging antithrombotic therapies. We also emphasize a number of questions that remain to be answered, and we identify hotspots for future research.

The Growth Factor Release from a Platelet-Rich Plasma Preparation Is Influenced by the Onset of Guttate Psoriasis: A Case Report

The involvement of platelets in immune and inflammatory processes is generally recognized; nevertheless, in psoriasis, their role is not clearly understood. We studied the in vitro growth factor release from a platelet-rich plasma preparation, the concentrated growth factors (CGF), in a case of a psoriasis subject three days before the onset of the papule. The CGF clots were incubated in a cell culture medium without growth supplements for 5 h and 1, 3, 6, 7, and 8 days, and the release kinetics of PDGF-AB, VEGF, TNF-α, and TGF-β1 were evaluated. The data, based on the results obtained during the case study, report a general increase in growth factor release in the psoriasis subject with respect to the healthy control, indicating an imbalance of growth factor production from blood cells. Although the results should be validated in the future, they show new aspects of this dermatological pathology, opening new possibilities both as the method of study, using CGF, and the involvement of platelets and growth factors in its development and maintenance.

Acute Atherosis Lesions at the Fetal-Maternal Border: Current Knowledge and Implications for Maternal Cardiovascular Health

Decidua basalis, the endometrium of pregnancy, is an important interface between maternal and fetal tissues, made up of both maternal and fetal cells. Acute atherosis is a uteroplacental spiral artery lesion. These patchy arterial wall lesions containing foam cells are predominantly found in the decidua basalis, at the tips of the maternal arteries, where they feed into the placental intervillous space. Acute atherosis is prevalent in preeclampsia and other obstetric syndromes such as fetal growth restriction. Causal factors and effects of acute atherosis remain uncertain. This is in part because decidua basalis is challenging to sample systematically and in large amounts following delivery. We summarize our decidua basalis vacuum suction method, which facilitates tissue-based studies of acute atherosis. We also describe our evidence-based research definition of acute atherosis. Here, we comprehensively review the existing literature on acute atherosis, its underlying mechanisms and possible short- and long-term effects. We propose that multiple pathways leading to decidual vascular inflammation may promote acute atherosis formation, with or without poor spiral artery remodeling and/or preeclampsia. These include maternal alloreactivity, ischemia-reperfusion injury, preexisting systemic inflammation, and microbial infection. The concept of acute atherosis as an inflammatory lesion is not novel. The lesions themselves have an inflammatory phenotype and resemble other arterial lesions of more extensively studied etiology. We discuss findings of concurrently dysregulated proteins involved in immune regulation and cardiovascular function in women with acute atherosis. We also propose a novel hypothesis linking cellular fetal microchimerism, which is prevalent in women with preeclampsia, with acute atherosis in pregnancy and future cardiovascular and neurovascular disease. Finally, women with a history of preeclampsia have an increased risk of premature cardiovascular disease. We review whether presence of acute atherosis may identify women at especially high risk for premature cardiovascular disease.

A risk-stratified approach to venous thromboembolism prophylaxis with aspirin or warfarin following total hip and knee arthroplasty: A cohort study

INTRODUCTION

Venous thromboembolism (VTE) and bleeding events following total knee and hip arthroplasty (TKA/THA) are associated with significant morbidity. Clinical guidelines recommend administration of pharmacologic VTE prophylaxis post-operatively, although controversy exists regarding optimal prophylactic strategies.

METHODS

We performed a retrospective cohort study in patients who underwent elective TKA/TKA in an academic medical center. Patients were stratified by surgery type (TKA/THA) and VTE risk determined by a novel risk stratification protocol and compared pre- and post-protocol implementation. Patients received warfarin pre-protocol and either aspirin or warfarin post-protocol for VTE prophylaxis. Natural language processing identified VTE events and ICD codes were used to identify bleeding events, with all events validated manually.

RESULTS

A total of 1379 surgeries were included for analysis, 839 TKAs and 540 THAs. Post-protocol implementation, 445 (94.1%) patients following TKA and 294 (97.4%) patients following THA received aspirin for VTE prophylaxis. A significant reduction in bleeding events (hazard ratio [HR] = 0.19, p = 0.048) was observed in low-risk THA patients treated with aspirin (post-protocol) compared patients treated with warfarin (pre-protocol). Bleeding events did not differ significantly between low-risk TKA patients treated with aspirin or warfarin. No significant differences in VTE events were observed following the protocol implementation.

CONCLUSIONS

The use of a novel risk stratification system to guide VTE prophylaxis selection between aspirin or warfarin following TKA and THA appears safe and effective. Among low-risk patients, aspirin use was associated with fewer bleeding events following THA, without an observed increase in VTE events.

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.

Contemporary Rates of Inferior Vena Cava Filter Thrombosis and Risk Factors

OBJECTIVE

Inferior vena cava thrombosis is an uncommon complication associated with inferior vena cava filters (IVCF), with literature citing rates ranging from 1% to 31%. Few observational studies describe risk factors associated with IVCF thrombosis, despite the significant clinical sequelae such as post-thrombotic syndrome, venous claudication, and venous ulceration. To better describe IVCF thrombosis and risk factors, data were queried from VQI-participating centers.

METHODS

IVCF data were obtained through the international VQI database from 2013 - 2019. Patients included in this analysis had two-year follow-up. Baseline demographics, medical comorbidities, medication, procedural, anatomical, and post-operative variables were assessed using Kaplan-Meier survival curves with log-rank tests, Student's t-tests, or Mann-Whitney U tests for IVCF thrombosis at two years. Cox regression analyses identified independent predictors of IVCF thrombosis. A subgroup analysis of those who presented with a venous thromboembolism (VTE) was also performed.

RESULTS

There were 62 US and Canadian VQI-participating centers, including 12,874 cases of IVCF placement. There 78 cases (1.3%) of IVCF thrombosis identified out of a total of 5,780 cases with two-year follow up. Those who experienced IVCF thrombosis had significantly lower rates of diabetes, coronary artery disease, pre-operative antiplatelet medications, pre-operative statins, as well as lower rates of discharge and follow up antiplatelet medications. On univariable analysis, cases of IVCF thrombosis also had higher rates of pulmonary emboli (PE) and VTE on admission, internal jugular venous access (versus femoral vein access), temporary IVCF use, follow up anticoagulation, follow up IVCF complication, follow up access site thrombosis, and rates of new or propagated DVT at follow up, and longer post-operative hospital stays. Multivariable analysis demonstrated independent predictors of IVCF thrombosis included new or propagated DVT at follow up (hazard ratio [HR]=16.3, 95% confident interval (CI) = 9.8 - 27.3, P<.001), no antiplatelet at follow up (HR=4.8, 95% CI= 1.9 - 12.5, P=.001), internal jugular venous access (HR=2.2, 95% CI=1.4 - 3.5, P=.001), VTE on admission (HR=2.7, 95% CI=1.4 - 5.1, P=.002), and temporary IVCF placement (HR=2.5, 95% CI = 1.1 - 5.6, P=.031). In an analysis of the subgroup of patients with VTE on admission, similar predictive factors were identified in a multivariable model, in addition, massive PE was also predictive of IVCF thrombosis in this subgroup.

CONCLUSION

The rate of IVCF thrombosis remained low in a contemporary international database. This study of over 5,000 patients with IVCFs suggests that antiplatelet therapy should be administered after IVCF placement to decreased risk of IVCF thrombosis.

A retrospective analysis of bleeding risk with rivaroxaban, enoxaparin, and aspirin following total joint arthroplasty or revision

STUDY OBJECTIVE

Rivaroxaban, enoxaparin, and aspirin are commonly used medications for thromboprophylaxis following lower extremity joint arthroplasty or revision. Previous research has demonstrated efficacy in preventing venous thromboembolism with each medication, however, the comparative risk of bleeding between them remains poorly understood. The aim of this study was to compare the odds of bleeding between rivaroxaban, enoxaparin, and aspirin following lower extremity joint arthroplasty or revision.

DESIGN

This is a 3-year retrospective cohort study.

SETTING

Data were obtained from 148 facilities across 55 states and territories of the United States.

PATIENTS

This study included 85,938 patients who underwent hip or knee arthroplasty or revision.

INTERVENTION

Patients received enoxaparin, rivaroxaban, or aspirin as monotherapy for thromboprophylaxis.

MEASUREMENTS

The primary outcome was all bleeding, classified as major or minor bleeding, occurring in the 40 days following surgery. The secondary outcome was venous thromboembolism.

MAIN RESULTS

Among 85,938 patients, 10,465 received rivaroxaban, 14,047 received enoxaparin, and 61,426 received aspirin. Bleeding occurred in 126 (1.20%) patients with rivaroxaban, 253 (1.80%) with enoxaparin, and 611 (0.99%) with aspirin. There was a significant increase in odds of bleeding in the enoxaparin compared to aspirin group odds ratio (OR) 1.18, 95% confidence interval (CI) 1.01-1.38, p = 0.042), and a trend toward increased odds of bleeding in rivaroxaban compared to aspirin group (OR 1.21, 95% CI 0.99-1.47, p = 0.058) and rivaroxaban compared to enoxaparin (OR 1.03, 95% CI 0.82-1.28, p = 0.827). Odds of venous thromboembolism were not statistically significant between all three study medications.

CONCLUSIONS

Among rivaroxaban, enoxaparin, and aspirin used for thromboprophylaxis in knee and hip arthroplasty or revision, aspirin had significantly decreased odds of bleeding complications compared to enoxaparin. Although not statistically significant, aspirin also had a trend toward decreased odds of bleeding complications compared to rivaroxaban. Our study results suggest that aspirin is a safer alternative for use in postoperative thromboprophylaxis following lower extremity joint arthroplasty or revision.

Platelets: Underestimated Regulators of Autoinflammation in Psoriasis

Platelets have long been known as mediators of hemostasis and, more recently, as mediators of thromboinflammation, although their physiopathological role has mostly been investigated in the context of disease of internal organs, such as liver and kidney, or systemic disorders. Of late, exciting recent data suggest that platelets may also play a role in inflammation at distal sites such as the skin: recent studies show that platelets, by engaging polymorphonuclear neutrophils (PMNs), contribute to local inflammation in the frequent skin disorder, psoriasis. In an experimental model, systemic depletion of platelets drastically attenuated skin inflammation by preventing PMN infiltration of the skin. A broader role of platelets in different types of skin inflammation is therefore likely, and in this paper, we specifically review recent advances in psoriasis. Special emphasis is given to the crosstalk with systemic platelet effects, which may be of interest in psoriasis-related cardiovascular comorbidities. Furthermore, we discuss the potential for platelet-centered interventions in the therapy for psoriasis.

Interplay between platelets and coagulation

Haemostasis stops bleeding at the site of vascular injury and maintains the integrity of blood vessels through clot formation. This regulated physiological process consists of complex interactions between endothelial cells, platelets, von Willebrand factor and coagulation factors. Haemostasis is initiated by a damaged vessel wall, followed with a rapid adhesion, activation and aggregation of platelets to the exposed subendothelial extracellular matrix. At the same time, coagulation factors aggregate on the procoagulant surface of activated platelets to consolidate the platelet plug by forming a mesh of cross-linked fibrin. Platelets and coagulation mutually influence each other and there are strong indications that, thanks to the interplay between platelets and coagulation, haemostasis is far more effective than the two processes separately. Clinically this is relevant because impaired interaction between platelets and coagulation may result in bleeding complications, while excessive platelet-coagulation interaction induces a high thrombotic risk. In this review, platelets, coagulation factors and the complex interaction between them will be discussed in detail.

Venous thromboembolism prevention protocol for adapting prophylaxis recommendations to the potential risk post total knee replacement: a randomized controlled trial

Background

Total knee replacement (TKR) is a major orthopedic surgery that is considered high risk for the development of venous thromboembolism (VTE).

Objective

The aim of this study is to evaluate the clinical outcomes that resulted from the use of a new proposed VTE risk stratification protocol for selecting a suitable extended VTE prophylaxis for post TKR surgery patients administered in conjunction with patient education programs.

Method

A randomized controlled trial was conducted in two medical centers in Saudi Arabia. A total of 242 patients were enrolled in the study, 121 patients in each group. The experimental group (A) was assessed by using the proposed VTE risk stratification protocol and also took part in patient education programs about TKR and its complications. The control group (B) was assessed by using the 2005 Caprini risk assessment tool and no education programs were given to this group. Both groups were followed for 35 days post operation.

Results

The mean age of the participants was 65.86 (SD 8.67) and the majority of them were female 137 (56.6%). The mean body mass index of the study sample was 32.46 (SD 5.51). There were no significant differences between the two groups except for surgery type; the proportion of bilateral TKR in group A was higher than in group B (69/121 (28.5%) vs. 40/121(16.5%), p<0.05). There were no confirmed pulmonary embolism cases in the study sample and diagnosis of deep-vein thrombosis was confirmed in 12/242 (5.0%) of patients: 1/121 (0.8%) in group A and 11/121 (9.1%) in group B (p<0.05). The readmission rate for all patients was 2.5% (6/242), all of whom were in group B (p<0.05).

Conclusion

The proposed VTE risk stratification protocol that was applied in conjunction with patient education programs reduced VTE complications and readmission events, post TKR surgery. Trial Registration: ClinicalTrials.gov: Identifier: NCT04031859.

Can the Caprini score predict thromboembolism and guide pharmacologic prophylaxis after primary joint arthroplasty?

Aims

Venous thromboembolism (VTE) has a 30-day mortality rate of between 10 and 30%. The Caprini score is a VTE risk assessment model, which assigns points to 20 past medical history and current health factors. We hypothesized that the Caprini score could predict VTE incidence and recommend prophylaxis following total joint arthroplasty.

Patients and methods

We performed a retrospective review of prospectively collected institutional data identifying Caprini scores on 2155 primary hip (n = 840) and knee (n = 1315) arthroplasties. Surgeons were blinded to Caprini scores when prescribing VTE prophylaxis. Patients were separated into prophylaxis groups receiving Aspirin (81 mg BID or 325 mg BID) or other (Rivaroxaban, Warfarin, Enoxaparin, Apixaban, Dabigatran, Heparin). Univariate, multivariate, and Cohen's effect size analyses assessed the predictive power of the Caprini score on VTE incidence.

Results

The mean Caprini score was 9.49 (5-25). A majority, 83% (1792) of patients were in the Aspirin group, and 17% (363) in the other group. Other prophylaxis patients had statistically significantly higher Caprini scores (10 vs. 9, p < 0.0001). Twenty-five (1.2%) patients developed VTE. Controlling for prophylaxis, higher Caprini scores increased VTE risk, but this wasn't statistically significant (p = 0.16). Multivariate analysis showed a non-significant effect for patients with BMIs >40 or Caprini scores ≥11 to predict VTE incidence in the Aspirin or other prophylaxis groups (p = 0.52 and p = 0.15 respectively). Cohen's effect size was small, comparing Caprini scores in patients who had and had not had a VTE in both Aspirin and other prophylaxis groups (Cohen's d = 0.25 and d = 0.16 respectively).

Conclusion

Surgeons rely on stronger pharmacologic prophylaxis for a select high risk group of their primary lower extremity total joint arthroplasty patients. When controlling for prophylaxis, the Caprini score had a small effect size and did not have the predictive power necessary to guide treatment.

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.

Aspirin for prevention of venous thromboembolism in recipients of major lower-limb orthopedic surgery: a systematic review of Level I evidence

INTRODUCTION

Major lower-limb orthopedic surgery recipients are at increased risk of venous thromboembolism (VTE). The optimal strategy for preventing VTE is a topic of ongoing debate. The use of aspirin has been implicated in reducing VTE events and is potentially advantageous compared to other agents in respect to cost, access, route of administration and reduced adverse effects such as bleeding.

EVIDENCE ACQUISITION

A systematic search for Level I evidence (systematic reviews and meta-analyses of randomised-controlled trials) was performed in April 2019 to evaluate the use of aspirin for primary and secondary VTE prophylaxis compared to alternative chemical and mechanical strategies. This search encompassed three electronic databases (Pubmed, Embase and the Cochrane Database of Systematic Reviews). All references of included studies were screened for additional studies. Data was compiled and compared to the recommendations and guidelines published by major institutions. Included studies were appraised with the aid of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist.

EVIDENCE SYNTHESIS

In total, 21 studies were included. Interventions and outcomes identified were heterogeneous across studies. Most statistical tests applied found no difference between aspirin and other interventions in regards to deep vein thrombosis, pulmonary embolism, bleeding and mortality outcomes.

CONCLUSIONS

Aspirin may be a viable alternative to established thromboprophylactic regimes for primary prevention of VTE, however in the setting of secondary prevention it is generally less efficacious. Future studies should have clearly identified and comparable outcome measures, with direct comparisons and assessment of intervention combination, dosing and treatment duration.

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.

The Effectiveness of Aspirin for Venous Thromboembolism Prophylaxis for Patients Undergoing Arthroscopic Rotator Cuff Repair

Venous thromboembolic disease (VTED) is a rare complication following arthroscopic rotator cuff repair (RCR). The American Academy of Orthopaedic Surgeons and the American College of Chest Physicians have no prophylaxis guidelines specific to shoulder arthroscopy, yet many surgeons prescribe aspirin following RCR. The purpose of this study was to evaluate the effectiveness of aspirin and mechanical prophylaxis compared with mechanical prophylaxis alone in preventing VTED following RCR. A total of 914 patients underwent RCR between January 2010 and January 2015. A retrospective case-control study was performed. The control group (n=484) consisted of patients treated with compression boots and early mobilization. The study group (n=430) used compression boots, early mobilization, and 81 mg/d of aspirin. The primary outcome was symptomatic VTED, including deep venous thrombosis (DVT) and pulmonary embolism (PE). A total of 7 VTED events occurred during the study period: 6 DVTs and 1 PE; 1 patient experienced both DVT and PE. The percentage of patients with VTED, DVT, and PE was 0.66%, 0.66%, and 0.11%, respectively. There was no significant difference for DVT or PE between the 2 groups. The incidence of DVT and PE was 0.62% and 0.00%, respectively, for the control group (no aspirin) and 0.70% and 0.23%, respectively, for the study group (aspirin). Aspirin does not lead to a clinically significant reduction in either DVT or PE rate in patients undergoing RCR. The authors conclude that the use of mechanical prophylaxis and early mobilization is a sufficient method of VTED prophylaxis in this low-risk population. [Orthopedics. 2019; 42(2):e187-e192.].

Comparative effectiveness of direct oral anticoagulants versus low-molecular weight heparins for the prevention of venous thromboembolism after total hip or knee replacement: A nationwide database cohort study

BACKGROUND

Venous thromboembolism (VTE) after total knee or hip replacement (TKR, THR) is usually prevented with low-molecular weight heparin (LMWH), and increasingly by direct oral anticoagulants (DOAC). The aim of the present study was to compare the benefit-risk and medical costs of DOAC vs. LMWH in a real-life setting.

METHODS

All patients with THR or TKR in France between Jan-1st 2013 and Sep-30th 2014, discharged to home, were identified and followed-up for 3 months in the French nationwide claims database, SNDS. DOAC users were 1:1 matched with LWMH users on gender, age and propensity score. Relative risks (RR) of hospitalized VTE, hospitalized bleeding and death were estimated using quasi-Poisson models. Medical costs were calculated according to the societal perspective, including total cost for outpatient claims and national DRG costs for hospitalisations.

RESULTS

Most DOAC users (≥ 98.8%) were matched to a LMWH patient. For the 63,238 matched THR patients, the 3-month absolute risk of VTE was 0.9‰ with DOAC and 2.5‰ with LMWH (RR = 0.35 [0.23 to 0.54]), of bleeding 1.8‰ and 2.1‰ (0.88 [0.62-1.25]), death 0.7‰ and 1.1‰ (0.68 [0.40-1.15]). For the 31,440 matched TKR patients, risks were 1.6‰ and 2.3‰ (0.69 [0.42-1.16]) for VTE, 2.4‰ and 3.8‰ (0.64 [0.43 to 0.97]) for bleeding, and 0.6‰ and 0.8‰ (0.69 [0.30-1.62]) for all-cause death. Mean medical costs were 28% and 21% lower with DOAC than LMWH for THR and TKR, respectively. This nationwide study found a very low risk of VTE, hospitalized bleeding and death after THR or TKR discharge in patients with VTE prevention in real-life setting, with better benefit-risk profiles of DOAC compared to LMWH, and associated cost savings.

Immune Factors in Deep Vein Thrombosis Initiation

Deep vein thrombosis (DVT) is a major origin of morbidity and mortality. While DVT has long been considered as blood coagulation disorder, several recent lines of evidence demonstrate that immune cells and inflammatory processes are involved in DVT initiation. Here, we discuss these mechanisms, in particular, the role of immune cells in endothelial activation, and the immune cascades leading to expression of adhesion receptors on endothelial cells. We analyze the specific recruitment and functional roles of different immune cells, such as mast cells and leukocytes, in DVT. Importantly, we also speculate how immune modulation could be used for DVT prevention with a lower risk of bleeding complications than conventional therapeutic approaches.