Below-knee cast immobilization and the risk of venous thrombosis: results from a large population-based case-control study

Dissecting the rationale for thromboprophylaxis in challenging surgical cases

Pulmonary embolism (PE) is a leading preventable cause of death in surgical patients, and rates of fatal PE are increasing. Individual assessment, to balance the risks of thrombosis and bleeding, is the key to providing appropriate prophylaxis. The risk assessment process includes use of evidence-based guidelines, literature published since the latest guidelines, large registries, and risk scoring systems together with clinical experience and judgment. Risk assessment is a dynamic process and needs to be updated both during the hospital stay and just prior to discharge since clinical events may change the level of risk. The final assessment may identify patients who require ongoing anticoagulant prophylaxis after discharge. The Caprini risk score is widely used in surgical patients and is a composite of the number of risk factors and their relative weights. The Caprini risk score set point for risk levels requiring anticoagulant prophylaxis varies depending on the type of surgical procedure, surgical population, and number of risk factors. Mandatory implementation of evidence-based care pathways is helpful in lowering PE-related mortality. This review presents several challenging cases, emphasizing the importance of employing all available assessment tools, including dynamic assessment of risk during hospitalization. Finally, the limitations of evidence-based guidelines in complex scenarios and the need to employ all available tools to properly protect very high-risk patients are emphasized.

Haemostatic, Inflammatory, and Haematological Biomarkers Among Orthopaedic Patients With Prolonged Immobilization and the Risk of Hypercoagulable States

Background Venous thromboembolism (VTE) is a common and potentially life-threatening complication in patients with lower limb traumatic fractures. Orthopaedic patients who experience trauma in the lower limbs with prolonged immobilization may experience a hypercoagulable state, which could eventually lead to the development of VTE. Therefore, this study aims to evaluate the changes in hypercoagulable markers, including haemostatic, inflammatory, and haematological biomarkers in orthopaedic trauma patients with prolonged immobilization. Materials/method This prospective cohort study was conducted at Hospital Universiti Sains Malaysia from August 2020 to March 2022. Every patient with fractures in the lower limbs was screened for eligibility, and patients who required immobilization for more than five days without receiving anticoagulant prophylaxis were recruited for this study. The laboratory tests, including D-dimer, fibrinogen, prothrombin time (PT), activated partial thromboplastin time (aPTT), erythrocyte sedimentation rate (ESR), and platelet count, were serially measured on day one and day five of hospitalization. The biomarkers were analyzed using a paired t-test, with a p-value <0.05 as a significant result. Results A total of 54 patients with fractures in the lower limbs, ages ranging from 12 to 50 years old, were involved in this study. The paired t-test analysis demonstrated that several biomarkers showed a significant increase in mean difference between day one and day five of immobilization, which included fibrinogen, ESR, and platelet count. The mean differences for each biomarker with fibrinogen were 0.66 g/L (p<0.001, 95% CI of mean difference: -1.04, -0.27), ESR increased by 17.98mm/hr (p<0.001, 95% CI of mean difference: -24.69, -11.27), and platelet count increased by 128.59×109/L (p<0.001, 95% CI of mean difference: -166.55, -90.64) on day five of immobilization. D-dimer was elevated in all patients on both post-trauma days; however, no significant difference was observed in this biomarker between day one and day five of immobilization. Conclusion In conclusion, our study found that fibrinogen, ESR, and platelet count levels were significantly increased in orthopaedic trauma patients with prolonged immobilization. The increase in these biomarkers indicates the body's reaction to tissue injury after trauma, which may contribute to the hypercoagulable states. Further research with a larger sample size is warranted to assess the viability of these biomarkers as potential diagnostic indicators for the development of VTE related to hypercoagulability.

The silent killer: Previously undetected pulmonary emboli that result in death after discharge

INTRODUCTION

Pulmonary embolism (PE) is a recognized cause of death in hospitalized trauma patients, yet less is known about PE after discharge.

PATIENTS & METHODS

All post-discharge, autopsy-demonstrated, fatal PE resulting from trauma within a large US county over six years were analyzed. Counts, percentages, mean values, SD, and IQR were calculated for all variables.

RESULTS

1848 trauma deaths were reviewed, of which 85% had an autopsy. Eighty-five patients died from PE after discharge from their initial injury. 53% were initially treated at non-trauma centers, and 9% did not seek medical assistance. 75% were injured by falling, and most injuries occurred in the lower extremities. 86% had an ISS <16, but 87% needed assistance or were bed-bound after injury, despite 75% having no mobility limitations before the injury. 53% died within one month of injury, and 91% within the first year. Before death, only 11% were prescribed chemical thromboprophylaxis or an antiplatelet agent, and only 8% were diagnosed with venous thromboembolism before death.

CONCLUSIONS

Fatal PE after discharge typically occurred following activity-limiting lower extremity injuries with an ISS<16.

The efficacy and safety of low-molecular-weight heparin in patients undergoing knee arthroscopic surgery and anterior cruciate ligament reconstruction

Purpose

To inveatigate how effective LMWH was at preventing venous thromboembolism (VTE), major bleeding events, and minor bleeding events after simple knee arthroscopic surgery and anterior cruciate ligament reconstruction (ACLR).

Methods

We conducted a comprehensive search of PubMed, EMBASE, Cochrane Library, and the CNKI database for potentially eligible articles. The outcomes were evaluated in terms of odds ratio (OR) and the associated 95% confidence intervals (CIs). Meta-analysis was performed using the Stata software and subgroup analyses were performed based on the surgical setting including ACLR and simple knee arthroscopic surgery.

Results

A total of eight studies with 2249 patients and 1794 controls were included in this meta-analysis. In patients undergoing simple knee arthroscopic surgery, LMWH prophylaxis did not bring a significant reduction in the risk of symptomatic deep venous thrombosis (DVT), symptomatic pulmonary embolism (PE), symptomatic VTE, and did not increase the risk of major bleeding events, but did have a higher risk of minor bleeding events (OR = 1.95, 95% CI 1.34-2.84, P = 0.000) and a lower risk of asymptomatic DVT (OR = 0.14, 95% CI 0.04-0.53, P = 0.004) in comparison with non-LMWH prophylaxis. In patients undergoing ACLR, LMWH prophylaxis did not bring a significant reduction in the risk of symptomatic DVT, symptomatic PE, symptomatic VTE, and did not increase the risk of major bleeding events and minor bleeding events, but did have a lower risk of asymptomatic DVT (OR = 0.43, 95% CI 0.23-0.78, P = 0.006).

Conclusion

When compared to a control group, this meta-analysis found that LMWH had little potential benefit in preventing major VTE (symptomatic VTE, symptomatic DVT, and symptomatic PE) after simple knee arthroscopy and ACLR. As a result, LMWH should not be considered routinely in patients undergoing knee arthroscopic surgery.

The influence of lower-leg injury and knee arthroscopy on natural anticoagulants and fibrinolysis

BACKGROUND

Patients with lower-leg injuries and those undergoing knee arthroscopy are at increased risk of developing venous thromboembolism. The mechanism is unknown, including the influence of lower-leg injury and knee arthroscopy on natural anticoagulant factors and fibrinolysis.

OBJECTIVES

To study the effect of lower-leg injury and knee arthroscopy on plasma levels of anticoagulant and fibrinolytic factors.

METHODS

We applied the following 2 designs to investigate this effect: a cross-sectional study for lower-leg trauma and a before-and-after study for knee arthroscopy. Plasma samples of POT-CAST- and POT-KAST-randomized clinical trial participants (collected shortly after lower-leg trauma or before or after arthroscopy) were analyzed for clot lysis time and levels of antithrombin, tissue factor pathway inhibitor, protein C, free protein S, plasminogen, tissue plasminogen activator, plasminogen activator inhibitor 1, antiplasmin, thrombin activatable fibrinolysis inhibitor, plasmin-antiplasmin, and D-dimer. For the effect of lower-leg injury, samples of 289 patients were compared with preoperative samples of 293 arthroscopy patients, acting as controls using linear regression and adjusting for age, sex, body mass index, comorbidities, and diurnal variation. For the effect of knee arthroscopy, mean changes were calculated for 277 patients using linear mixed models adjusted for diurnal variation. Parameters other than CLT and D-dimer were measured in smaller subsets.

RESULTS

In lower-leg injury patients, most parameters were stable, whereas D-dimer increased. After arthroscopy, most parameters decreased (especially clot lysis time, D-dimer, plasminogen, and anticoagulant factors), whereas tissue plasminogen activator and thrombin activatable fibrinolysis inhibitor slightly increased.

CONCLUSION

In contrast to lower-leg injury, knee arthroscopy was associated with decreased natural anticoagulant factor levels. Neither lower-leg injury nor knee arthroscopy affected in vivo fibrinolysis.

Haemostasis and Inflammatory Parameters as Potential Diagnostic Biomarkers for VTE in Trauma-Immobilized Patients

Venous thromboembolism (VTE), which encompasses deep venous thrombosis (DVT) and pulmonary embolism (PE), is a major public health concern due to its high incidences of morbidity and mortality. Patients who have experienced trauma with prolonged immobilization are at an increased risk of developing VTE. Plasma D-dimer levels have been known to be elevated in trauma patients, and they were closely correlated with the number of fractures. In other words, plasma D-dimer levels cannot be used as the only indicator of VTE in trauma cases. Given the limitations, further study is needed to explore other potential biomarkers for diagnosing VTE. To date, various established and novel VTE biomarkers have been studied in terms of their potential for predicting VTE, diagnostic performance, and improving clinical therapy for VTE. Therefore, this review aims to provide information regarding classic and essential haemostasis (including prothrombin time (PT), activated partial thromboplastin time (aPTT), D-dimer, fibrinogen, thrombin generation, protein C, protein S, antithrombin, tissue factor pathway inhibitor, and platelet count) and inflammatory biomarkers (C-reactive protein, erythrocyte sedimentation rate, and soluble P-selectin) as potential diagnostic biomarkers that can predict the risk of VTE development among trauma patients with prolonged immobilization. Thus, further advancement in risk stratification using these biomarkers would allow for a better diagnosis of patients with VTE, especially in areas with limited resources.

Perioperative Thromboprophylaxis Is Associated With Lower Risk of Venous Thromboembolism After Knee Arthroscopy

PURPOSE

To determine the rate of symptomatic venous thromboembolism (VTE) among patients undergoing arthroscopic knee procedures, risk factors associated with postoperative VTE, and current perioperative thromboprophylaxis prescription patterns associated with this population in the United States.

METHODS

Medical records for patients ≥18 years of age were queried from the Mariner database using Current Procedural Terminology codes for knee arthroscopy performed in the United States from 2010 to 2020 in this cross-sectional study. Patients who received thromboprophylaxis and those diagnosed with VTE, including deep-vein thrombosis or pulmonary embolism, within 90 days of surgery were identified using International Classification of Diseases and National Drug Codes. Two multivariable logistic regression models were used to identify VTE risk factors and likelihood of perioperative thromboprophylaxis. Covariates included procedure type, age, oral contraceptive pill (OCP) use, and medical comorbidities.

RESULTS

A total of 718,289 patients met inclusion criteria and 7,618 patients (1.06%) experienced VTE, including deep-vein thrombosis (n = 6,394, 0.9%) and/or pulmonary embolism (n = 2,211, 0.3%). A total of 10,769 patients (1.5%) filled perioperative thromboprophylaxis, including aspirin (n = 5,353, 0.7%), low-molecular-weight heparin (n = 4,563, 0.6%), and oral factor Xa inhibitors (n = 947, 0.1%). Perioperative thromboprophylaxis was associated with decreased odds of experiencing VTE (adjusted odds ratio [aOR] 0.65, 95% confidence interval [CI] 0.51-0.80). Procedure types categorized as moderate-to-greater risk were associated with increased odds of VTE (aOR 1.42, 95% CI 1.34-1.50). OCP use (aOR 1.63, 95% CI 1.38-1.91), obesity (aOR 1.17, 95% CI 1.11-1.24), renal disease (aOR 1.33, 95% CI 1.18-1.50) and congestive heart failure (aOR 1.30, 95% CI 1.13-1.50) were associated with increased odds of VTE.

CONCLUSIONS

While the overall rate of symptomatic VTE following knee arthroscopy remains low, procedure types that are more complex and generally require restrictive rehabilitation protocols, OCP use, obesity, renal disease, and congestive heart failure are associated with increased odds of postoperative VTE. Conversely, the use of perioperative thromboprophylaxis is associated with significantly lower VTE risk.

LEVEL OF EVIDENCE

III, retrospective comparative prognostic trial.

Effect of lower‐leg trauma and knee arthroscopy on procoagulant phospholipid‐dependent activity

Background

Lower-leg injury and knee arthroscopy are both associated with venous thromboembolism (VTE). The mechanism of VTE in both situations is unknown, including the role of procoagulant microparticles. This may provide useful information for individualizing thromboprophylactic treatment in both patient groups.

Objective

We aimed to study the effect of (1) lower-leg trauma and (2) knee arthroscopy on procoagulant phospholipid-dependent (PPL) activity plasma levels.

Methods

POT-(K)CAST trial participants who did not develop VTE were randomly selected for the current study. Plasma was collected shortly after lower-leg trauma or before and after knee arthroscopy. For aim 1, samples of 67 patients with lower-leg injury were compared with control samples (preoperative samples of 74 patients undergoing arthroscopy). Linear regression was used to obtain mean ratios (natural logarithm retransformed data), adjusted for age, sex, body mass index, infections, and comorbidities. For aim 2, pre- and postoperative samples of 49 patients undergoing arthroscopy were compared using paired t tests. PPL activity was measured using modified activated factor X-dependent PPL clotting assay.

Results

For aim 1, PPL activity levels were almost threefold higher in patients with lower-leg injury compared with controls, that is, mean ratio, 2.82 (95% confidence interval [CI], 1.98-4.03). For aim 2, postoperative PPL activity levels did not change significantly, that is, mean change, -0.72 mU/mL (95% CI, -2.03 to 0.59).

Conclusion

Lower-leg trauma was associated with increased plasma levels of PPL activity, in contrast to knee arthroscopy. Lower-leg trauma triggers the release of procoagulant microparticles.

Targeted proteomics for evaluating risk of venous thrombosis following traumatic lower-leg injury or knee arthroscopy

INTRODUCTION

Patients with lower-leg cast immobilization and patients undergoing knee arthroscopy have an increased risk of venous thrombosis (VT). Guidelines are ambiguous about thromboprophylaxis use, and individual risk factors for developing VT are often ignored. To assist in VT risk stratification and guide thromboprophylaxis use, various prediction models have been developed. These models depend largely on clinical factors and provide reasonably good C-statistics of around 70%. We explored using protein levels in blood plasma measured by multiplexed quantitative targeted proteomics to predict VT. Our aim was to assess whether a VT risk prediction model based on absolute plasma protein quantification is possible.

METHODS

We used internal standards to quantify proteins in less than 10 μl plasma. We measured 270 proteins in samples from patients scheduled for knee arthroscopy or with lower-leg cast immobilization. The two prospective POT-(K)CAST trails allow complementary views of VT signature in blood, namely pre and post trauma, respectively. From approximately 3000 patients, 31 patients developed VT who were included and matched with double the number of controls.

RESULTS

Top discriminating proteins between cases and controls included APOC3, APOC4, APOC2, ATRN, F13B, and F2 in knee arthroscopy patients and APOE, SERPINF2, B2M, F13B, AFM, and C1QC in patients with lower-leg cast. A logistic regression model with cross-validation resulted in C-statistics of 88.1% (95% CI: 85.7-90.6%) and 79.6% (95% CI: 77.2-82.0%) for knee arthroscopy and cast immobilization groups respectively.

CONCLUSIONS

Promising C-statistics merit further exploration of the value of proteomic tests for predicting VT risk upon additional validation.

Deep Venous Thrombosis With Symptomatic Bilateral Pulmonary Embolism After Using an Infrapatellar Strap for Patellofemoral Pain in an Athletic Cardiothoracic Surgeon

ABSTRACT

Knee braces and patellar straps are frequently prescribed devices for treatment of patellofemoral pain syndrome. In this report, we describe the occurrence of localized deep venous thrombosis (DVT) after use of an infrapatellar strap. Until now, external mechanical compression has not been recognized as a cause of DVT. In young and athletic patients presenting with DVT, after exclusion of the most prominent risk factors, untraditional causes should be considered to mistakenly label a DVT as unprovoked.

Development of the Plymouth VTE Risk Score for patients treated with lower limb immobilisation in a cast or boot

There is approximately a 2% risk of clinically significant VTE following temporary lower limb immobilisation after injury with an ankle immobilising plaster cast or boot. There is evidence that thromboprophylaxis for lower limb immobilised patients reduces the risk of VTE by approximately 50% but there is no international consensus as to which patients should receive thromboprophylaxis. The Plymouth VTE Risk Score was developed to identify patients at particular risk of VTE, in order to offer chemical prophylaxis to reduce their VTE risk. The score showed high completion rates, reliability and consistency. Using the Plymouth VTE Risk Score Version 3 (2014), we found an incidence of clinical VTE of 0.36% with 37.6% of patients being advised to have thromboprophylaxis. This is a lower VTE incidence than in most other studies of this patient group, which is of the order of 2 to 3%. The optimal RAM to use in clinical practice is yet to be defined, further clinical research is needed to accurately stratify patient risk and to define optimal risk treatment levels. We suggest research should focus on comparative clinical studies of risk assessment models.

Risque thromboembolique veineux chez les patients traumatisés d’un membre inférieur nécessitant une immobilisation : vers une approche individualisée

Un traumatisme d’un membre inférieur nécessitant une immobilisation est une situation à risque de développement de maladie thromboembolique veineuse (MTEV). Cependant, les recommandations et les pratiques varient notablement d’un pays à un autre et d’un centre à un autre. Cette revue narrative a pour objectifs de décrire l’épidémiologie, la prévention et les algorithmes de prédiction de la MTEV chez les patients traumatisés d’un membre inférieur nécessitant une immobilisation. L’incidence de la MTEV varie selon les études du fait de la grande hétérogénéité des patients inclus (de l’entorse de cheville à une lésion chirurgicale) et du fait des différents critères d’évaluation utilisés. L’incidence des événements thromboemboliques veineux symptomatiques est estimée à 2,0 % (intervalle de confiance à 95 % : 1,3 à 2,7). L’efficacité de la thromboprophylaxie a été démontrée dans des méta-analyses récentes. Cependant, la confiance à accorder à ces résultats est médiocre, car de nombreux essais présentaient des faiblesses méthodologiques. L’étude la plus importante et la plus récente ne montre pas de bénéfice de la prévention par héparine de bas poids moléculaire sur les événements symptomatiques dans une population non ciblée. Ces résultats suggèrent d’adopter une démarche personnalisée en réservant la prophylaxie aux patients à risque. Plusieurs scores existent pour évaluer le risque thromboembolique individuel. La prise en compte des caractéristiques du patient, du traumatisme et de l’immobilisation permet d’identifier un large sous-groupe de patients chez qui la prévention ne semble pas utile et un sous-groupe de patients à haut risque où la prévention devrait être prescrite, voire renforcée. En conclusion, lors d’un traumatisme d’un membre inférieur nécessitant une immobilisation, l’indication d’une thromboprophylaxie devrait être guidée par l’évaluation individuelle du risque thrombotique.

Venous Thromboembolism in Patients Discharged From the Emergency Department With Ankle Fractures: A Population-Based Cohort Study

STUDY OBJECTIVE

Temporary lower limb immobilization may be a risk for venous thromboembolism. The purpose of this study was to examine the 90-day incidence of venous thromboembolism among patients discharged from an emergency department (ED) with ankle fractures requiring temporary immobilization. Secondary objectives were to examine individual factors associated with venous thromboembolism in this population and to compare the risk of venous thromboembolism in patients with ankle fractures against a priori-selected control groups.

METHODS

This was a retrospective cohort study using province-wide health datasets from Ontario, Canada. We included patients aged 16 years and older discharged from an ED between 2013 and 2018 with closed ankle fractures requiring temporary immobilization. We estimated 90-day incidence of venous thromboembolism after ankle fracture. A Cox proportional hazards model was used to evaluate risk factors associated with venous thromboembolism, censoring at 90 days or death. Patients with ankle fractures were then propensity score matched to 2 control groups: patients discharged with injuries not requiring lower limb immobilization (ie, finger wounds and wrist fractures) to compare relative hazard of venous thromboembolism.

RESULTS

There were 86,081 eligible patients with ankle fractures. Incidence of venous thromboembolism within 90 days was 1.3%. Factors associated with venous thromboembolism were older age (hazard ratio [HR]: 1.18; 95% confidence interval [CI]: 1.00 to 1.39), venous thromboembolism or superficial venous thrombosis history (HR: 5.18; 95% CI: 4.33 to 6.20), recent hospital admission (HR: 1.33; 95% CI: 1.05 to 1.68), recent nonankle fracture surgery (HR: 1.58; 95% CI: 1.30 to 1.93), and subsequent surgery for ankle fracture (HR: 1.80; 95% CI: 1.48 to 2.20). In the matched cohort, patients with ankle fractures had an increased hazard of venous thromboembolism compared to matched controls with finger wounds (HR: 6.31; 95% CI: 5.30 to 7.52) and wrist fractures (HR: 5.68; 95% CI: 4.71 to 6.85).

CONCLUSION

The 90-day incidence of venous thromboembolism among patients discharged from the ED with ankle fractures requiring immobilization was 1.3%. These patients had a 5.7- to 6.3-fold increased hazard compared to matched controls. Certain patients immobilized for ankle fractures are at higher risk of venous thromboembolism, and this should be recognized by emergency physicians.

Perioperative Management of Orthopaedic Patients with Hematologic Disorders: A Critical Analysis Review

Perioperative management of orthopaedic patients with a hematologic disorder is a complex endeavor that requires a multidisciplinary team-based approach. A team composed of an experienced orthopaedic surgeon, an anesthesiologist, and a hematologist is necessary to achieve optimal outcomes. Patients with hemophilia and other complex hematologic disorders should be managed at, or in consultation with a hematologist at, a comprehensive hemophilia center. Bleeding disorders and inherited thrombophilia present unique challenges for the perioperative management of orthopaedic surgery. Comprehensive preoperative planning and familiarity with treatment guidelines can help to minimize these risks. Knowledge of the disease processes outlined in this article will provide orthopaedic surgeons with the requisite background knowledge that is needed to initiate safe and effective treatment strategies involving this high-risk patient population.

Thromboembolic risk stratification by TRiP(cast) score to rationalise thromboprophylaxis in patients with lower leg trauma requiring immobilisation: a study protocol of the casting stepped-wedge cluster randomised trial

INTRODUCTION

Patients with lower limb trauma requiring orthopaedic immobilisation may be at risk of venous thromboembolism but opinions differ about who may benefit from thromboprophylactic anticoagulant treatment.The aim of this CASTING study is to demonstrate the safety of thromboprophylaxis based on the Thrombosis Risk Prediction for patients with cast immobilisation (TRiP(cast) score with regards to the 3-month incidence of symptomatic venous thromboembolism events in low-risk patients not receiving thromboprophylaxis, as well as the usefulness of this strategy on the rate of patients receiving anticoagulant treatment in comparison to current practice.

METHODS AND ANALYSIS

CASTING will be a stepped-wedge cluster randomised controlled clinical trial, performed in 15 emergency departments in France and Belgium. With their informed consent, outpatients admitted to one of the participating emergency departments for a lower limb trauma requiring orthopaedic immobilisation without surgery will be included. All centres will begin the trial with the 'observational period' and, every 2 weeks, 1 centre will be randomly assigned to switch to the 'interventional period' and to apply the TRiP(cast) score, in which only patients with a score ≥7 will receive thromboprophylactic anticoagulant treatment. The primary endpoint is the rate of clinical thromboembolic events within 90 days following the inclusion of low-risk patients not receiving thromboprophylaxis.

ETHICS AND DISSEMINATION

The protocol has been approved by the Comité de Protection des Personnes Sud I (Ethics Review ID-RCB: 2019-A01829-48) for France and the Comité d'éthique hôpital-facultaire Saint Luc (N° B403201941338) for Belgium. It is carried out in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. The findings of this study will be disseminated in peer-reviewed journals and at scientific conferences.

TRIAL REGISTRATION NUMBER

NCT04064489.

Oral contraceptives and hormone replacement therapy: How strong a risk factor for venous thromboembolism?

Exogenous hormone therapies, such as combined oral contraceptives (COC) and hormone replacement therapy (HRT), cause blood hypercoagulability and are a risk factor for venous thromboembolism (VTE). There is controversy on how strong this "provoking" risk factor is, and how other risk factors may synergise VTE risk. We aim to review the latest literature on the risk of initial and recurrent VTE with COC and HRT use to provide guidance for decision-making about duration of anticoagulation, and guide future research efforts.

High risk of venous thromboembolism after orthopedic surgery in patients with thrombophilia

OBJECTIVE

This study aimed at evaluating the effect of thrombophilia on the risk of venous thromboembolism (VTE) in patients undergoing any type of orthopedic surgery.

BACKGROUND

Patients undergoing orthopedic surgery are at high risk for VTE. Although patients with thrombophilia have an increased risk of VTE, it is currently unclear whether there is a synergetic effect in patients with thrombophilia who undergo orthopedic surgery.

METHODS

Data from a large population-based case-control study (the Multiple Environmental and Genetic Assessment [MEGA] of risk factors for venous thrombosis study) were used. Odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for age, sex, and body mass index (BMI) (ORadj) were calculated for patients undergoing any orthopedic intervention.

RESULTS

Of 4721 cases and 5638 controls, 263 cases and 94 controls underwent orthopedic surgery. Patients who had any orthopedic intervention in the year before the index date were at higher risk of VTE (ORadj 3.7; 95% CI, 2.9-4.8) than those who did not undergo any orthopedic surgery. There was an additionally increased risk in patients with factor V Leiden (OR 17.5, 95% CI, 4.1-73.6), non-O blood group (OR 11.2; 95% CI, 3.4-34.0), or elevated plasma levels of factor VIII (OR 18.6; 95% CI, 7.4-46.9) all relative to patients without these defects, not undergoing orthopedic surgery.

CONCLUSIONS

Patients with factor V Leiden, high levels of factor VIII, or blood group non-O were found to have a high risk of VTE after orthopedic surgery. Identification of these patients may enable individualized thromboprophylactic treatment to efficiently reduce VTE risk.

Risk of Venous Thromboembolism in Transgender People Undergoing Hormone Feminizing Therapy: A Prevalence Meta-Analysis and Meta-Regression Study

BACKGROUND

Although venous thromboembolism (VTE) is a recognized side effect of some formulations of estrogen therapy, its impact in transgender people remains uncertain. The aim of this study was to define pooled prevalence estimate and correlates of VTE in Assigned Males at Birth (AMAB) trans people undergoing gender affirming hormone therapy.

METHODS

A thorough search of MEDLINE, COCHRANE LIBRARY, SCOPUS and WEB OF SCIENCE databases was carried out to identify suitable studies. Quality of the articles was scored using the Assessment Tool for Prevalence Studies. Data were combined using random effects models and the between-study heterogeneity was assessed by the Cochrane's Q and I².

RESULTS

The eighteen studies included gave information about 11,542 AMAB undergoing gender affirming hormone therapy. The pooled prevalence of VTE was 2% (95%CI:1-3%), with a large heterogeneity (I² = 89.18%, P<0.0001). Trim-and-fill adjustment for publication bias produced a negligible effect on the pooled estimate. At the meta-regression analysis, a higher prevalence of VTE was significantly associated with an older age (S=0.0063; 95%CI:0.0022,0.0104, P=0.0027) and a longer length of estrogen therapy (S=0.0011; 95%CI:0.0006,0.0016, P<0.0001). When, according to the meta-regression results, the analysis was restricted to series with a mean age ≥37.5 years, the prevalence estimate for VTE increased up to 3% (95%CI:0-5%), but with persistence of a large heterogeneity (I² = 88,2%, P<0.0001); studies on younger participants (<37.5 years) collectively produced a pooled VTE prevalence estimate of 0% (95%CI:0-2%) with no heterogeneity (I² = 0%, P=0.97). Prevalence estimate for VTE in series with a mean length of estrogen therapy ≥53 months was 1% (95%CI:0-3%), with persistent significant heterogeneity (I² = 84,8%, P=0.0006); studies on participants subjected to a shorter length of estrogen therapy (<53 months), collectively produced a pooled VTE prevalence estimate of 0% (95%CI:0-3%) with no heterogeneity (I² = 0%, P=0.76).

CONCLUSIONS

The overall rate of VTE in AMAB trans people undergoing gender affirming hormone therapy was 2%. In AMAB population with <37.5 years undergoing estrogen therapy for less than 53 months, the risk of VTE appears to be negligible. Further studies are warranted to assess whether different types and administration routes of estrogen therapy could decrease the VTE risk in AMAB trans people over 37.5 years subjected to long-term therapy.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk/PROSPERO/], identifier [CRD42021229916].

Prophylaxis of Venous Thromboembolism in Ankle and Foot Surgeries

Venous thromboembolism (VTE) is among the most feared complications by orthopedists both for due to its potentially lethal outcome and the uncertainties related to its prevention. Despite the vast literature on VTE prevention in major orthopedic surgeries, little is known about it in ankle and foot procedures. In orthopedics, adequate thromboprophylaxis requires a careful assessment of the thrombotic and hemorrhagic risks based on the procedure to be performed, as well as and knowledge on anticoagulant agents. The presentis review has the goal of assessing the risk of developingdiscusses VTE risk assessment, the modalities of thromboprophylaxis modalities, and the drugs used, with an emphasis on foot and ankle surgeries.

Clinical risk assessment model to predict venous thromboembolism risk after immobilization for lower-limb trauma

BACKGROUND

Patients with lower-limb trauma requiring immobilization have an increased risk of venous thromboembolism (VTE). While thromboprophylaxis for all patients seems not effective, targeted thromboprophylaxis in high risk patients may be an appropriate alternative. Therefore, we aimed to develop and validate a risk assessment model for VTE risk: the TRiP(cast) score (Thrombosis Risk Prediction following cast immobilization).

METHODS

In this prediction model study, for development, data were used from the MEGA study (case-control study into the etiology of VTE) and for validation, data from the POT-CAST trial (randomized trial on the effectiveness of thromboprophylaxis following cast immobilization) were used. Model discrimination was calculated by estimating the Area Under the Curve (AUC). For model calibration, observed and predicted risks were assessed.

FINDINGS

The TRiP(cast) score includes 14 items; one item for trauma severity (or type), one for type of immobilization and 12 items related to patients' characteristics. Validation analyses showed an AUC of 0.74 (95%CI 0.61-0.87) in the complete dataset (n = 1250) and 0.72 (95%CI 0.60-0.84) in the imputed data set (n = 1435). The calibration plot shows the degree of agreement between the observed and predicted risks (intercept 0.0016 and slope 0.933). Using a cut-off score of 7 points in the POT-CAST trial (incidence 1.6%), the sensitivity, specificity, positive and negative predictive values were 76.1%, 51.2%, 2.5%, and 99.2%, respectively.

INTERPRETATION

The TRiP(cast) score provides a helpful tool in daily clinical practice to accurately stratify patients in high versus low-risk categories in order to guide thromboprophylaxis prescribing. To accommodate implementation in clinical practice a mobile phone application has been developed.

FUNDING

ZonMW VIMP grant:17110200011.

Incidence of Deep Venous Thrombosis Associated With Proximal Hamstring Rupture

Background:

Rates of deep venous thrombosis (DVT) have been studied for most common orthopaedic injuries. However, rates and risk factors have not been published for proximal hamstring injuries.

Purpose:

To determine the incidence of symptomatic DVT associated with proximal hamstring rupture and associations with prophylactic anticoagulation.

Study Design:

Case series; Level of evidence, 4.

Methods:

Inclusion criteria included all complete and, in a separate cohort, partial proximal hamstring ruptures treated by the senior author from 2007 through 2018 with at least 8 weeks of follow-up. Tendinopathy without tear was excluded. No DVT screening was performed. Charts of patients with symptomatic DVT were reviewed for the treatment method, the presence of imaging-confirmed DVT or pulmonary embolism, and risk factors for DVT. No patients received postinjury DVT prophylaxis. Surgical patients were routinely instructed to take aspirin (325 mg bid) or apixaban (2.5 mg bid) for 4 weeks. Patients with risk factors for DVT received enoxaparin (40 mg daily) for 2 weeks followed by aspirin (325 mg bid) for 2 weeks.

Results:

A total of 144 complete proximal hamstring ruptures were included: 132 treated operatively and 12 treated nonoperatively. There were 10 DVTs associated with the injury, for an overall rate of 6.9%. Five of the DVTs were diagnosed preoperatively in patients who had not received DVT prophylaxis; the other 5 were diagnosed postoperatively in patients on DVT prophylaxis. Six of the 10 DVTs had identifiable risk factors. All patients with postoperatively diagnosed DVTs were on prophylactic aspirin or enoxaparin. In the partial proximal hamstring rupture cohort of 114 ruptures, there were no DVTs.

Conclusion:

There is a high incidence of DVT associated with complete proximal hamstring ruptures (6.9%) despite many patients receiving DVT prophylaxis. This is substantially higher than that in other lower extremity injuries. Clinicians should have a high index of suspicion for DVT after these injuries, and postinjury DVT prophylaxis may be warranted.

Different strategies for pharmacological thromboprophylaxis for lower-limb immobilisation after injury: systematic review and economic evaluation

BACKGROUND

Thromboprophylaxis can reduce the risk of venous thromboembolism (VTE) during lower-limb immobilisation, but it is unclear whether or not this translates into meaningful health benefit, justifies the risk of bleeding or is cost-effective. Risk assessment models (RAMs) could select higher-risk individuals for thromboprophylaxis.

OBJECTIVES

To determine the clinical effectiveness and cost-effectiveness of different strategies for providing thromboprophylaxis to people with lower-limb immobilisation caused by injury and to identify priorities for future research.

DATA SOURCES

Ten electronic databases and research registers (MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Database of Abstracts of Review of Effects, the Cochrane Central Register of Controlled Trials, Health Technology Assessment database, NHS Economic Evaluation Database, Science Citation Index Expanded, ClinicalTrials.gov and the International Clinical Trials Registry Platform) were searched from inception to May 2017, and this was supplemented by hand-searching reference lists and contacting experts in the field.

REVIEW METHODS

Systematic reviews were undertaken to determine the effectiveness of pharmacological thromboprophylaxis in lower-limb immobilisation and to identify any study of risk factors or RAMs for VTE in lower-limb immobilisation. Study quality was assessed using appropriate tools. A network meta-analysis was undertaken for each outcome in the effectiveness review and the results of risk-prediction studies were presented descriptively. A modified Delphi survey was undertaken to identify risk predictors supported by expert consensus. Decision-analytic modelling was used to estimate the incremental cost per quality-adjusted life-year (QALY) gained of different thromboprophylaxis strategies from the perspectives of the NHS and Personal Social Services.

RESULTS

Data from 6857 participants across 13 trials were included in the meta-analysis. Thromboprophylaxis with low-molecular-weight heparin reduced the risk of any VTE [odds ratio (OR) 0.52, 95% credible interval (CrI) 0.37 to 0.71], clinically detected deep-vein thrombosis (DVT) (OR 0.40, 95% CrI 0.12 to 0.99) and pulmonary embolism (PE) (OR 0.17, 95% CrI 0.01 to 0.88). Thromboprophylaxis with fondaparinux (Arixtra®, Aspen Pharma Trading Ltd, Dublin, Ireland) reduced the risk of any VTE (OR 0.13, 95% CrI 0.05 to 0.30) and clinically detected DVT (OR 0.10, 95% CrI 0.01 to 0.94), but the effect on PE was inconclusive (OR 0.47, 95% CrI 0.01 to 9.54). Estimates of the risk of major bleeding with thromboprophylaxis were inconclusive owing to the small numbers of events. Fifteen studies of risk factors were identified, but only age (ORs 1.05 to 3.48), and injury type were consistently associated with VTE. Six studies of RAMs were identified, but only two reported prognostic accuracy data for VTE, based on small numbers of patients. Expert consensus was achieved for 13 risk predictors in lower-limb immobilisation due to injury. Modelling showed that thromboprophylaxis for all is effective (0.015 QALY gain, 95% CrI 0.004 to 0.029 QALYs) with a cost-effectiveness of £13,524 per QALY, compared with thromboprophylaxis for none. If risk-based strategies are included, it is potentially more cost-effective to limit thromboprophylaxis to patients with a Leiden thrombosis risk in plaster (cast) [L-TRiP(cast)] score of ≥ 9 (£20,000 per QALY threshold) or ≥ 8 (£30,000 per QALY threshold). An optimal threshold on the L-TRiP(cast) receiver operating characteristic curve would have sensitivity of 84-89% and specificity of 46-55%.

LIMITATIONS

Estimates of RAM prognostic accuracy are based on weak evidence. People at risk of bleeding were excluded from trials and, by implication, from modelling.

CONCLUSIONS

Thromboprophylaxis for lower-limb immobilisation due to injury is clinically effective and cost-effective compared with no thromboprophylaxis. Risk-based thromboprophylaxis is potentially optimal but the prognostic accuracy of existing RAMs is uncertain.

FUTURE WORK

Research is required to determine whether or not an appropriate RAM can accurately select higher-risk patients for thromboprophylaxis.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017058688.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Physical activity and risk of venous thromboembolism: systematic review and meta-analysis of prospective cohort studies

The inverse association between physical activity and arterial thrombotic disease is well established. Evidence on the association between physical activity and venous thromboembolism (VTE) is divergent. We conducted a systematic review and meta-analysis of published observational prospective cohort studies evaluating the associations of physical activity with VTE risk. MEDLINE, Embase, Web of Science, and manual search of relevant bibliographies were systematically searched until 26 February 2019. Extracted relative risks (RRs) with 95% confidence intervals (CIs) for the maximum versus minimal amount of physical activity groups were pooled using random effects meta-analysis. Twelve articles based on 14 unique prospective cohort studies comprising of 1,286,295 participants and 23,753 VTE events were eligible. The pooled fully-adjusted RR (95% CI) of VTE comparing the most physically active versus the least physically active groups was 0.87 (0.79–0.95). In pooled analysis of 10 studies (288,043 participants and 7069 VTE events) that reported risk estimates not adjusted for body mass index (BMI), the RR (95% CI) of VTE was 0.81 (0.70–0.93). The associations did not vary by geographical location, age, sex, BMI, and methodological quality of studies. There was no evidence of publication bias among contributing studies. Pooled observational prospective cohort studies support an association between regular physical activity and low incidence of VTE. The relationship does not appear to be mediated or confounded by BMI.

A comparison of two interventions in the treatment of severe ankle sprains and lateral malleolar avulsion fractures

AIM

Stable ankle injuries are highly prevalent in the UK. Prevention of complications and reoccurrence is essential. The literature shows that plaster of Paris and AirLoc brace are clinically effective treatments for such injuries. However, there is no research measuring patients' satisfaction with these treatments. This study compared options in the treatment of severe ankle sprains and distal fibular avulsion fractures from patients' perspectives. The aim was to determine patients' preferred treatment between below knee plaster cast and AirLoc brace in the management of stable ankle injuries.

METHOD

A total of 39 patients who presented at an urban hospital with stable ankle injuries were recruited into a randomised controlled trial. Patient satisfaction levels were measured by questionnaire one week into treatment. The null hypothesis was 'there is no significant difference in satisfaction levels between the two devices'.

FINDINGS

There were statistically significant higher patient satisfaction levels in the AirLoc group compared to the plaster cast group. After analysis by the unrelated t -test, the null hypothesis was rejected. Comfort, daily activities, sleep, work and social life were the main contributing factors. Additionally, 67% of the AirLoc group compared to 46% of the plaster cast group were able to return to work. The number needed to treat for one additional AirLoc patient to return to work was 4.8 (five patients).

CONCLUSION

Patients' preferred treatment is the AirLoc brace. The inquiry method could be used to provide patient-centred care in other fields.

Sauna bathing reduces the risk of venous thromboembolism: a prospective cohort study

Emerging evidence suggests there is an inverse and independent association between sauna bathing and arterial thrombotic disease. However, the potential association between sauna bathing and venous thromboembolism (VTE) has not yet been investigated. We aimed to assess the prospective association between frequency of sauna bathing and the risk of VTE. Baseline sauna bathing habits were assessed in 2242 men aged 42-61 years without a history of VTE in the Kuopio Ischemic Heart Disease prospective cohort. Cox proportional hazards models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for VTE. During a median follow-up of 24.9 years, 146 (6.5%) incident VTE events were recorded. In age-adjusted analyses, the HRs 95% (CIs) of VTE were 0.67 (0.47-0.96) and 0.95 (0.53-1.70) for participants who had 2-3 and ≥ 4 sauna sessions per week respectively compared with participants who had ≤ 1 sauna session per week. After further adjustment for several established risk factors including lifestyle factors, the corresponding HRs (95% CIs) were 0.67 (0.46-0.96) and 0.92 (0.51-1.68) respectively. Having sauna baths was associated with a reduced risk of VTE in a middle-aged male Caucasian population. Further studies in other populations and age groups are required to confirm these findings.

Venous thromboembolism risk stratification for patients with lower limb trauma and cast or brace immobilization

BACKGROUND

Thromboprophylaxis for patients with non-surgical isolated lower-limb trauma requiring immobilization is a matter of debate. Our aim was to develop and validate a clinical risk- stratification model based on Trauma, Immobilization and Patients' characteristics (the TIP score).

METHODS

The TIP score criteria and the cut-off were selected by a consensus of international experts (n = 27) using the Delphi method. Retrospective validation was performed in a population-based case-control study (MEGA study). The potential score's impact in anticoagulant treatment was assessed in a prospective single-center observational cohort study.

FINDINGS

After four successive rounds, 30 items constituting the TIP score were selected: thirteen items for trauma, three for immobilization and 14 for patient characteristics were selected, each rated on a scale of 1 to 3. In the validation database, the TIP score had an AUC of 0·77 (95% CI 0.70 to 0.85). Using the cut-off proposed by the experts (≥5) and assuming a prevalence of 1·8%, the TIP scores had a sensitivity, specificity and negative predictive values of 89·9%, 30·7% and 99·4% respectively. In the prospective cohort, 84·2% (165/196) of all the patients concerned who presented at the emergency department had a low VTE risk not requiring thromboprophylaxis according to their TIP scores. The 3-month rate of symptomatic VTE was 1/196 [95% CI 0.1-2.8] this patient was in the sub-group TIP score ≥5.

CONCLUSION

For patients with non-surgical lower-limb trauma and orthopedic immobilization, the TIP score allows an individual VTE risk-assessment and shows promising results in guiding thromboprophylaxis.

Effect of prothrombotic genotypes on the risk of venous thromboembolism in patients with and without ischemic stroke. The Tromsø Study

Essentials Prothrombotic genotypes may agument the risk of venous thromboembolism (VTE) after ischemic stroke. We studied this effect in a case-cohort study using a genetic risk score. In stroke patients, a one-category increase in the genetic risk score was associated with a 50% higher relative risk of VTE. The risk of VTE in stroke patients increased with an increasing number of risk alleles. SUMMARY: Background Patients with ischemic stroke have a transiently increased risk of subsequent venous thromboembolism (VTE). Prothrombotic genotypes may augment VTE risk under conditions of high thrombosis risk related to stroke. Aims To investigate the effect of prothrombotic genotypes in patients with ischemic stroke on the risk of VTE in a population-based case-cohort study. Methods Cases with incident VTE (n = 664) and a randomly selected age-weighted subcohort (n = 1817) were sampled from three surveys of the Tromsø Study (1994-2008). Participants were genotyped for ABO (rs8176719), F5 (rs6025), F2 (rs1799963), FGG (rs2066865) and F11 (rs2036914) single-nucleotide polymorphisms (SNPs). Cox regression models were used to calculate hazard ratios (HRs) for incident VTE according to individual SNPs and categories of risk alleles (5-SNP score; 0-1, 2, 3-4 and ≥ 5) in participants with and without ischemic stroke. Results There were 192 patients with incident stroke, of whom 43 developed VTE during a median of 15.2 years of follow-up. The risk alleles of individual SNPs augmented the elevated VTE risk brought about by ischemic stroke. In stroke patients, a one-category increase in the genetic risk score was associated with a 50% higher relative risk of overall VTE (HR 1.5, 95% confidence interval [CI] 1.3-1.8) and an 80% higher relative risk of provoked VTE (HR 1.8, 95% CI 1.5-2.1). Stroke patients with ≥ 5 risk alleles had a 12-fold (HR 11.7, 95% CI 4.1-33.3) higher relative risk of VTE than stroke-free participants with 0-1 risk alleles. Conclusions Prothrombotic genotypes increased the risk of VTE in stroke patients, and the risk increased with an increasing number of risk alleles.

Physical activity and risk of first-time venous thromboembolism

BACKGROUND

Physical activity may have a protective effect against venous thromboembolism (VTE). The aim of this study was to investigate the association between leisure time physical activity, occupational physical activity, and the risk of VTE in men and women separately.

METHODS

The population-based, prospective Venous thromboEmbolism In Northern Sweden (VEINS) cohort study included 108,025 participants of health examinations between 1985 and 2014. Physical activity data were collected by questionnaire. Participants were followed from health examination to first-time VTE event, death, emigration or the end of the study. All VTE events were validated by reviewing medical records and radiology reports.

RESULTS

During 1,496,669 person-years, 2054 participants experienced VTE. Women who performed leisure time physical activity at least once a week had a lower risk of first-time VTE (hazard ratio (HR) 0.83; 95% confidence interval (CI) 0.71-0.98 after adjustments) compared with women with less or no physical activity. Furthermore, women with high occupational physical activity also had a lower risk of VTE (HR 0.85; 95% CI 0.74-0.98). In men, there was no consistent association between either measure of physical activity and the risk of VTE.

CONCLUSION

We found an association between increased physical activity and a lower risk of first-time VTE in women.

Individual risk factors predictive of venous thromboembolism in patients with temporary lower limb immobilization due to injury: a systematic review

Essentials Thromboprophylaxis after lower limb injury is often based on complex risk stratification. Our systematic review identified variables predicting venous thromboembolism (VTE) in this group. Age and injury type were commonly reported to increase the odds of VTE (odds ratio 1.5-3.48). We found limited evidence to support the use of other risk factors within prediction models. SUMMARY: Background Patients immobilized after lower limb injury are at risk of venous thromboembolism (VTE). There is international variation in the use of thromboprophylaxis for such patients. Risk-based strategies have been adopted to aid decision making in many settings. The accuracy of these strategies is unclear. Objectives A systematic review was undertaken to identify all individual patient-identifiable risk factors linked to any VTE outcome following lower limb immobilization. Methods Several electronic databases were searched from inception to May 2017. Any studies that included a measurement of VTE as a patient outcome in adults requiring temporary immobilization (e.g. leg cast or brace in an ambulatory setting) for an isolated lower limb injury and reported risk factor variables were included. Descriptive statistics and thematic analysis were used to synthesize the evidence. Results Our database search returned 4771 citations, of which 15 studies reporting outcome data on 80 678 patients were eligible for analysis. Risk-factor associations were reported through regression analyses, non-parametric tests and descriptive statistics. All studies were assessed as at moderate or serious risk of bias using the ROBINS-I risk of bias tool. Advancing age and injury type were the only individual risk factors demonstrating a reproducible association with increased symptomatic and/or asymptomatic VTE rates. Several risk factors currently used in scoring tools did not appear to be robustly evaluated for subsequent association with VTE within these studies. Conclusions Clinicians should be aware of the limited evidence to support individual risk factors in guiding thromboprophylaxis use for this patient cohort.

Symptomatic venous thromboembolism after non-operatively treated foot or ankle injury

The purpose was to assess the incidence and risk factors associated with symptomatic venous thromboembolism in patients undergoing below knee immobilization for non-operative foot or ankle injury. We included all foot and ankle patients between January 2005 and May 2016 who underwent non-operative management using below knee immobilization with cast, splint, brace, and/or boot. The primary outcome was the development of a venous thromboembolism within 90 days of immobilization initiation. Of 6,088 patients, twenty-three (0.38%) developed a venous thromboembolism. Risk factors for venous thromboembolism were age>50 years, unremovable immobilization, Achilles tendon rupture, Modified Charlson Comorbidity Index>2, patients on chemoprophylaxis, varicose veins, history of venous thromboembolism, known hypercoagulability disorder, and rheumatoid arthritis. Routine thromboprophylaxis after below-knee immobilization for non-operative foot or ankle injury may be beneficial in these specific subpopulations. These data can facilitate more substantive shared decision-making between providers and patients with respect to use of thromboprophylaxis. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

High risk of recurrent venous thrombosis in patients with lower-leg cast immobilization

Essentials The risk of recurrent venous thrombosis (VT) after leg-cast in patients with prior VT is unknown. In a nested case-control study within the MEGA follow-up study we aimed to estimate this risk. Patients with a history of VT who require lower-leg cast have a 4.5-fold risk for recurrence. This relative risk translates to an absolute risk for recurrent VT of about 3.2% within 3 months. SUMMARY: Background Patients with lower-leg cast immobilization have a substantially increased risk of developing a first venous thrombosis (VT), whereas the risk in patients with a history of VT is as yet unknown. Aims To estimate the risk of recurrent VT after lower-leg cast immobilization in patients with a history of VT. Methods A case-control study nested within a cohort of 4597 patients with a first VT who were followed over time for recurrence from 1999 to 2010 (MEGA follow-up study). Participants completed a questionnaire on risk factors for recurrent thrombosis, including having a cast in the first 3 months before a recurrence (cases) or a random 3-month period during follow-up for participants without recurrence (controls). In total, 2723/4597 (59%) participants returned the questionnaire. Odds ratios (ORs), adjusted for age and sex, were calculated to compare risks of recurrence between subjects with and without a cast. Results A total of 2525/2723 participants (93%) filled out information on cast immobilization and were included in the analysis (451 cases; 2074 controls). Twenty (1.0%) controls and 10 (2.2%) cases reported having had a lower-leg cast in the 3 months before the control or recurrence date (adjusted OR, 2.4; 95% confidence Interval [CI], 1.1-5.3). We cross-checked the data with these patients' medical records. Cast application within 3 months was verified in seven (0.3%) controls vs. six (1.3%) cases, leading to an adjusted OR of 4.5 (95% CI, 1.5-14.0) and corresponding cumulative incidence of 3.2%. Conclusions Lower-leg cast immobilization increases the risk of recurrent VT in the 3 months after its application in patients with a history of VT.

Cardiovascular resistance to thrombosis in 13-lined ground squirrels

13-lined ground squirrels (Ictidomys tridecemlineatus) enter hibernation as a survival strategy during extreme environmental conditions. Typical ground squirrel hibernation is characterized by prolonged periods of torpor with significantly reduced heart rate, blood pressure, and blood flow, interrupted every few weeks by brief interbout arousals (IBA) during which blood flow fluctuates dramatically. These physiological conditions should increase the risk of stasis-induced blood clots and myocardial ischemia. However, ground squirrels have adapted to survive repeated bouts of torpor and IBA without forming lethal blood clots or sustaining lethal ischemic myocardial damage. The purpose of this study was to determine if ground squirrels are resistant to thrombosis and myocardial ischemia during hibernation. Blood markers of coagulation, fibrinolysis, thrombosis, and ischemia, as well as histological markers of myocardial ischemia were measured throughout the annual hibernation cycle. Hibernating ground squirrels were also treated with isoprenaline to induce myocardial ischemia. Thrombin-antithrombin complex levels were significantly reduced (p < 0.05) during hibernation, while D-dimer level remained unchanged throughout the annual cycle, both consistent with an antithrombotic state. During torpor, the ground squirrels were in a hyperfibrinolytic state with an elevated ratio of tissue plasminogen activator complexed with plasminogen activator inhibitor to total plasminogen activator inhibitor (p < 0.05). Histological markers of myocardial ischemia were reversibly elevated during hibernation with no increase in markers of myocardial cell death in the blood. These data suggest that ground squirrels do not form major blood clots during hibernation through suppression of coagulation and a hyperfibrinolytic state. These animals also demonstrate myocardial resistance to ischemia.

Sex hormones and venous thromboembolism - from contraception to hormone replacement therapy

The use of sex hormones such as combined oral contraceptives (COC) or hormone replacement therapy (HRT) increases the risk for venous thromboembolism (VTE) considerably, especially in patients with an increased intrinsic risk for thromboembolic complications. Despite public and media attention and increasing scientific evidence, prescription patterns seem to be hard to change. It is well recognized that the patient's baseline risk is the most relevant factor in the absolute risk for developing VTE. The relative risk increase associated with sex hormones, depends on the type and dosage of hormones, the route of application (oral, vaginal, transdermal), and for COC, on the specific combination of oestrogen and gestagen components. Consequently, a careful decision for or against any specific type of hormone treatment needs to be based on an assessment of the patient's risk profile (disposition) as well as on the treatment-associated risks and benefits (exposition). This review discusses the most common sex hormone treatments in contraception and HRT, the relevance for VTE risk patients, and strategies to counsel patients with regard to hormone use according to their risk profiles. Keywords: Oral contraceptives, hormonal contraception, hormone replacement therapy, venous thromboembolism.

Pulmonary embolism

Pulmonary embolism (PE) is caused by emboli, which have originated from venous thrombi, travelling to and occluding the arteries of the lung. PE is the most dangerous form of venous thromboembolism, and undiagnosed or untreated PE can be fatal. Acute PE is associated with right ventricular dysfunction, which can lead to arrhythmia, haemodynamic collapse and shock. Furthermore, individuals who survive PE can develop post-PE syndrome, which is characterized by chronic thrombotic remains in the pulmonary arteries, persistent right ventricular dysfunction, decreased quality of life and/or chronic functional limitations. Several important improvements have been made in the diagnostic and therapeutic management of acute PE in recent years, such as the introduction of a simplified diagnostic algorithm for suspected PE as well as phase III trials demonstrating the value of direct oral anticoagulants in acute and extended treatment of venous thromboembolism. Future research should aim to address novel treatment options (for example, fibrinolysis enhancers) and improved methods for predicting long-term complications and defining optimal anticoagulant therapy parameters in individual patients, and to gain a greater understanding of post-PE syndrome.

Latest Innovations in the Treatment of Venous Disease

Venous disease is more common than peripheral arterial disease. Pathophysiologically, venous disease can be associated with obstruction, reflux, or both. A common feature in chronic venous disease is ambulatory venous hypertension. Inflammatory and pro-thrombotic mechanisms can be activated. The current therapies, including compression, ablation, and recanalization are discussed.

Repair of Chronic Achilles Ruptures Has a High Incidence of Venous Thromboembolism

BACKGROUND

Despite the low incidence of deep vein thrombosis (DVT) in foot and ankle surgery, some authors report a high incidence of symptomatic DVT following Achilles tendon rupture. The purpose of this study was to identify DVT risk factors inherent to Achilles tendon repair to determine which patients may benefit from prophylaxis.

METHODS

One hundred and thirteen patient charts were reviewed following elective and nonelective Achilles tendon repair. For elective repair of insertional or noninsertional Achilles tendinopathy, parameters examined included lateral versus prone positioning and the presence versus absence of a flexor hallucis longus transfer. For nonelective repair, acute Achilles tendon ruptures were compared to chronic Achilles tendon ruptures.

RESULTS

Of 113 Achilles tendon repairs, 3 venous thromboembolism (VTE) events (2.65%) occurred including 2 pulmonary emboli (1.77%). Seventeen of these repairs were chronic Achilles tendon ruptures, and all 3 VTE events (17.6%) occurred within this subgroup. Elevated body mass index was associated with VTE in patients with chronic Achilles ruptures although this did not reach significance ( P = .064). No VTE events were reported after repair of 28 acute tendon ruptures or after 68 elective repairs of tendinopathy. Two patients with misdiagnosed partial Achilles tendon tears were excluded because they experienced a VTE event 3 weeks and 5 weeks after injury, prior to surgery.

CONCLUSION

In our retrospective review, chronic Achilles ruptures had a statistically significant higher incidence of VTE compared with acute Achilles ruptures ( P = .048) or elective repair ( P = .0069). Pharmaceutical anticoagulation may be considered for repair of chronic ruptures. Repair of acute ruptures and elective repair may not warrant routine prophylaxis due to a lower incidence of VTE.

LEVELS OF EVIDENCE

Prognostic, Level III: Case Control Study.

Thromboprophylaxis after Knee Arthroscopy and Lower-Leg Casting

BACKGROUND

The use of thromboprophylaxis to prevent clinically apparent venous thromboembolism after knee arthroscopy or casting of the lower leg is disputed. We compared the incidence of symptomatic venous thromboembolism after these procedures between patients who received anticoagulant therapy and those who received no anticoagulant therapy.

METHODS

We conducted two parallel, pragmatic, multicenter, randomized, controlled, open-label trials with blinded outcome evaluation: the POT-KAST trial, which included patients undergoing knee arthroscopy, and the POT-CAST trial, which included patients treated with casting of the lower leg. Patients were assigned to receive either a prophylactic dose of low-molecular-weight heparin (for the 8 days after arthroscopy in the POT-KAST trial or during the full period of immobilization due to casting in the POT-CAST trial) or no anticoagulant therapy. The primary outcomes were the cumulative incidences of symptomatic venous thromboembolism and major bleeding within 3 months after the procedure.

RESULTS

In the POT-KAST trial, 1543 patients underwent randomization, of whom 1451 were included in the intention-to-treat population. Venous thromboembolism occurred in 5 of the 731 patients (0.7%) in the treatment group and in 3 of the 720 patients (0.4%) in the control group (relative risk, 1.6; 95% confidence interval [CI], 0.4 to 6.8; absolute difference in risk, 0.3 percentage points; 95% CI, -0.6 to 1.2). Major bleeding occurred in 1 patient (0.1%) in the treatment group and in 1 (0.1%) in the control group (absolute difference in risk, 0 percentage points; 95% CI, -0.6 to 0.7). In the POT-CAST trial, 1519 patients underwent randomization, of whom 1435 were included in the intention-to-treat population. Venous thromboembolism occurred in 10 of the 719 patients (1.4%) in the treatment group and in 13 of the 716 patients (1.8%) in the control group (relative risk, 0.8; 95% CI, 0.3 to 1.7; absolute difference in risk, -0.4 percentage points; 95% CI, -1.8 to 1.0). No major bleeding events occurred. In both trials, the most common adverse event was infection.

CONCLUSIONS

The results of our trials showed that prophylaxis with low-molecular-weight heparin for the 8 days after knee arthroscopy or during the full period of immobilization due to casting was not effective for the prevention of symptomatic venous thromboembolism. (Funded by the Netherlands Organization for Health Research and Development; POT-KAST and POT-CAST ClinicalTrials.gov numbers, NCT01542723 and NCT01542762 , respectively.).

Venous Thrombosis Risk after Cast Immobilization of the Lower Extremity: Derivation and Validation of a Clinical Prediction Score, L-TRiP(cast), in Three Population-Based Case-Control Studies

BACKGROUND

Guidelines and clinical practice vary considerably with respect to thrombosis prophylaxis during plaster cast immobilization of the lower extremity. Identifying patients at high risk for the development of venous thromboembolism (VTE) would provide a basis for considering individual thromboprophylaxis use and planning treatment studies. The aims of this study were (1) to investigate the predictive value of genetic and environmental risk factors, levels of coagulation factors, and other biomarkers for the occurrence of VTE after cast immobilization of the lower extremity and (2) to develop a clinical prediction tool for the prediction of VTE in plaster cast patients.

METHODS AND FINDINGS

We used data from a large population-based case-control study (MEGA study, 4,446 cases with VTE, 6,118 controls without) designed to identify risk factors for a first VTE. Cases were recruited from six anticoagulation clinics in the Netherlands between 1999 and 2004; controls were their partners or individuals identified via random digit dialing. Identification of predictor variables to be included in the model was based on reported associations in the literature or on a relative risk (odds ratio) > 1.2 and p ≤ 0.25 in the univariate analysis of all participants. Using multivariate logistic regression, a full prediction model was created. In addition to the full model (all variables), a restricted model (minimum number of predictors with a maximum predictive value) and a clinical model (environmental risk factors only, no blood draw or assays required) were created. To determine the discriminatory power in patients with cast immobilization (n = 230), the area under the curve (AUC) was calculated by means of a receiver operating characteristic. Validation was performed in two other case-control studies of the etiology of VTE: (1) the THE-VTE study, a two-center, population-based case-control study (conducted in Leiden, the Netherlands, and Cambridge, United Kingdom) with 784 cases and 523 controls included between March 2003 and December 2008 and (2) the Milan study, a population-based case-control study with 2,117 cases and 2,088 controls selected between December 1993 and December 2010 at the Thrombosis Center, Fondazione IRCCS Ca' Granda-Ospedale Maggiore Policlinico, Milan, Italy. The full model consisted of 32 predictors, including three genetic factors and six biomarkers. For this model, an AUC of 0.85 (95% CI 0.77-0.92) was found in individuals with plaster cast immobilization of the lower extremity. The AUC for the restricted model (containing 11 predictors, including two genetic factors and one biomarker) was 0.84 (95% CI 0.77-0.92). The clinical model (consisting of 14 environmental predictors) resulted in an AUC of 0.77 (95% CI 0.66-0.87). The clinical model was converted into a risk score, the L-TRiP(cast) score (Leiden-Thrombosis Risk Prediction for patients with cast immobilization score), which showed an AUC of 0.76 (95% CI 0.66-0.86). Validation in the THE-VTE study data resulted in an AUC of 0.77 (95% CI 0.58-0.96) for the L-TRiP(cast) score. Validation in the Milan study resulted in an AUC of 0.93 (95% CI 0.86-1.00) for the full model, an AUC of 0.92 (95% CI 0.76-0.87) for the restricted model, and an AUC of 0.96 (95% CI 0.92-0.99) for the clinical model. The L-TRiP(cast) score resulted in an AUC of 0.95 (95% CI 0.91-0.99). Major limitations of this study were that information on thromboprophylaxis was not available for patients who had plaster cast immobilization of the lower extremity and that blood was drawn 3 mo after the thrombotic event.

CONCLUSIONS

These results show that information on environmental risk factors, coagulation factors, and genetic determinants in patients with plaster casts leads to high accuracy in the prediction of VTE risk. In daily practice, the clinical model may be the preferred model as its factors are most easy to determine, while the model still has good predictive performance. These results may provide guidance for thromboprophylaxis and form the basis for a management study.

Prevalence of Acute Deep Vein Thrombosis in Patients with Ankle and Foot Fractures Treated with Nonoperative Management-A Pilot Study

The prevalence of deep vein thrombosis (DVT) among patients with ankle and foot fractures in Australia treated nonsurgically is unknown. Indications for thromboprophylaxis screening and management are unclear. The primary outcome was the prevalence rate of DVT among nonsurgically managed ankle and foot fracture patients. Patients were enrolled into a prospective cross-sectional pilot study at an outpatient hospital fracture clinic. DVT risk factors and symptoms were recorded at time of recruitment followed by referral for compression duplex ultrasonography. Independent t-test and Fisher exact test were used to assess the significance of these variables with DVT. A total of 72 patients were included in the final analysis. Overall, 11% (8/72) of patients had DVT-seven distal DVTs and one proximal DVT. Four were symptomatic including the patient with a proximal thrombus. In comparison, the majority of patients were asymptomatic of DVT (63/72). A significant risk factor found to be associated with DVT was age ≥ 45 (p = 0.013) years, and a lack of symptoms (p = 0.006) was associated with no DVT. This pilot study is the first in Australia to investigate the prevalence of DVT in this specific subgroup of patients. We found a prevalence of 11% of DVT in a small group of patients with age ≥ 45 years, being the only significant associated risk factor. Future larger scale prospective studies are warranted to confirm these results.