Preventing venous thromboembolism in medical patients

What Constitutes High Risk for Venous Thromboembolism? Comparing Approaches to Determining an Appropriate Threshold

Background

Guidelines recommend pharmacological venous thromboembolism (VTE) prophylaxis only for high-risk patients, but the probability of VTE considered "high-risk" is not specified. Our objective was to define an appropriate probability threshold (or range) for VTE risk stratification and corresponding prophylaxis in medical inpatients.

Methods

Patients were adults admitted to any of 10 Cleveland Clinic Health System hospitals between December 2020 and August 2021 (N = 41,036). Hospital medicine physicians and internal medicine residents from included hospitals were surveyed between June and November 2023 (N = 214). We compared five approaches to determining a threshold: decision analysis, maximizing the sensitivity and specificity of a logistic regression model, deriving a probability from a point-based model, surveying physicians' understanding of VTE risk, and deriving a probability from physician behavior. For each approach, we determined the probability threshold above which a patient would be considered high-risk for VTE. We applied each threshold to the Cleveland Clinic VTE risk assessment model (CCM) and calculated the percentage of the 41,036 patients in our cohort who would be considered eligible for prophylaxis due to their high-risk status. We compared these hypothetical prophylaxis rates with physicians' observed prophylaxis rates.

Results

The different approaches yielded thresholds ranging from 0.3% to 5.4%, corresponding inversely with hypothetical prophylaxis rates of 0.2% to 75%. Multiple thresholds clustered between 0.52% to 0.55%, suggesting an average hypothetical prophylaxis rate of approximately 30%, whereas physicians' observed prophylaxis rates ranged from 48% to 76%.

Conclusions

Multiple approaches to determining a probability threshold for VTE prophylaxis converged to suggest an optimal threshold of approximately 0.5%. Other approaches yielded extreme thresholds that are unrealistic for clinical practice. Physicians prescribed prophylaxis much more frequently than the suggested rate of 30%, indicating opportunity to reduce unnecessary prophylaxis. To aid in these efforts, guidelines should explicitly quantify high-risk.

Evaluation of the Padua Prediction Score ability to predict venous thromboembolism in Israeli non-surgical hospitalized patients using electronic medical records

Venous thromboembolism (VTE) is considered a leading safety concern during hospitalization. The Padua Predication Score (PPS) is a risk model conceived to predict VTE among non-surgical hospitalized patients. The study aim was to evaluate the PPS ability to predict VTE in Israeli non-surgical hospitalized patients using data from electronic medical records. A single center, large-scale, historic cohort study of hospitalized non-surgical patients was conducted. Outcomes included clinically diagnosed symptomatic VTE events, bleeding events, and mortality during hospitalization and up to 90 days thereafter, and readmission up to 90 days after discharge. 5117 patient records were analyzed after screening and validation. 1120 (22%) patients were defined per PPS as high-risk, of which 277 (24.7%) were prophylactically treated. The low-risk group included 3997 (78%) patients. Prevalence of symptomatic VTE was low. Overall, 14 (0.27%) VTE events were diagnosed: 3 cases in the high-risk group (0.27%) and 11 (0.28%) in the low-risk group, with no significant difference, p = 0.768. Prophylactic treatment among the high-risk patients did not significantly improve VTE incidence: 1/277 (0.36%) treated vs. 2/843 (0.24%), p = 0.343. There was no significant difference between the study groups regarding the rates of bleeding, unexplained mortality or readmission. PPS was not found to be an efficient tool for identification of non-surgical hospitalized patients with high risk for clinically significant VTE.

[Pharmacological Thromboprophylaxis in Acutely Ill Hospitalized Medical Patients]

Venous thromboembolic events (VTE) occur in approximately 50% of cases during or following hospitalization; VTE are a major cause of morbidity and mortality. Thromboprophylaxis for 6 to 14 days with heparins or fondaparinux has been demonstrated to be effective in VTE prevention in patients hospitalized for acute medical illnesses and reduced mobility. Nevertheless, the level of recommendation has been gradually downgraded as the benefit has been mainly demonstrated on the basis of systematic imaging diagnosed events. Direct oral anticoagulants have been assessed only as an extended prophylaxis, and are currently not recommended in medical thromboprophylaxis. Assessing the risk of VTE and bleeding in medical patients is complex. VTE and bleeding risk assessment scores were constructed but have not been validated. In order to improve the adequacy of prescriptions for thromboprophylaxis, the impact of different interventions has been the subject of several studies but these yielded varying results. The aim of this review is to analyze the indications for thromboprophylaxis in a medical setting with the latest available data.

Anticoagulation in Venous Thromboembolism Prophylaxis in Medically Ill Patients: Potential Impact of NOACs

While substantial evidence supports the use of standard-duration injectable anticoagulants for venous thromboembolism (VTE) prophylaxis, consensus is mixed about which agents may be preferred in acutely ill patients with ongoing need of VTE prophylaxis past the first 10-day duration of hospital stay and post-discharge. Non-vitamin K antagonist oral anticoagulants (NOACs) provide Factor Xa inhibition to prevent the thrombin generation essential in thromboembolism development, but evidence for the efficacy and safety of most NOACs is conflicting regarding extended-duration prophylaxis. Enoxaparin, a preferred injectable anticoagulant in standard-duration VTE prophylaxis, has shown an increased risk of major bleeding events when used in extended-duration prophylaxis, which outweighs its benefit. Rivaroxaban has demonstrated efficacy in extended-duration prophylaxis, but both rivaroxaban and apixaban have shown increased risks of major bleeding. Betrixaban remains the only NOAC approved in the USA for extended-duration VTE prophylaxis, and it demonstrates efficacy, with fewer adverse effects than other NOACs. This review evaluates the appropriateness of different NOAC agents compared with current therapies for the extended-duration VTE prophylaxis setting in medically ill populations.

Impact of once-daily versus twice-daily dosing frequency on adherence to chronic medications among patients with venous thromboembolism

Background

Multiple daily dosing may be negatively associated with patient medication adherence; however, adherence-related data are lacking in a patient population with venous thromboembolism (VTE).

Objective

To assess the adherence rates between once-daily (OD) and twice-daily (BID) dosing regimens of chronic medications in patients with VTE.

Methods

We analyzed the PharMetrics Integrated Claims database (claims of commercial insurers in the US) from 1 January 2004, through 31 December 2009. Adult patients with continuous insurance coverage, newly initiated on diabetes mellitus or hypertension medication, and having at least one VTE diagnosis were included. Adherence to OD and BID therapies was calculated by using two measures: medication possession ratio (MPR) and proportion of days covered (PDC). Adherence was defined as an MPR or PDC ≥0.8. Multivariate logistic regressions were conducted to compare the probability of adherence between the OD and BID groups adjusting for baseline confounders.

Results

A total of 4,867 OD and 1,069 BID patients were identified. Mean duration of exposure to therapy for OD and BID patients was 386 and 356 days (p = 0.011), respectively. Based on MPR, 69 % of OD and 62 % of BID patients were adherent (p < 0.001). For PDC at 12 months, the proportion of adherent patients for the OD and BID groups was 45 and 36 % (p < 0.001), respectively. Adjusted odds ratios (95 % CI) of adherence for the OD relative to BID group were 1.61 (1.37–1.89) based on MPR (p < 0.001) and 1.46 (1.16–1.83) based on PDC at 12 months (p = 0.001).

Conclusions

This study demonstrates that VTE patients treated with chronic medications on OD dosing regimens were associated with an approximately 39–61 % higher likelihood of adherence compared with subjects on BID dosing regimens.

Electronic supplementary material

The online version of this article (doi:10.1007/s40271-013-0020-5) contains supplementary material, which is available to authorized users.

Retrospective analysis of a novel regimen for the prevention of venous thromboembolism in nephrotic syndrome

BACKGROUND AND OBJECTIVES

Venous thromboembolism (VTE) occurs in 7%-40% of nephrotic patients. The risk of VTE depends on the severity and underlying cause of nephrotic syndrome. This study investigated the use of low-dose prophylactic anticoagulation to prevent VTE in patients with nephrotic syndrome caused by primary glomerulonephritis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Since 2006, all patients presenting with nephrotic syndrome to Imperial College Kidney and Transplant Centre have been considered for treatment with a novel anticoagulation prophylaxis regimen. All cases of nephrotic syndrome secondary to primary membranous nephropathy, minimal-change disease, and FSGS over a 5-year period were retrospectively reviewed. Patients with serum albumin<2.0 g/dl received prophylactic-dose low-molecular-weight heparin or low-dose warfarin; patients with albumin levels of 2.0-3.0 g/dl received aspirin, 75 mg once daily. All thrombotic events and bleeding complications were recorded.

RESULTS

A total of 143 patients received the prophylactic anticoagulation regimen. Median follow-up was 154 weeks (range, 30-298 weeks). The cohort had features associated with a high risk of developing VTE; 40% of the cohort had an underlying diagnosis of membranous nephropathy, and the initial median serum albumin was 1.5 g/dl (range, 0.5-2.9 g/dl). No VTE occurred in patients established on prophylaxis for at least 1 week. VTE was diagnosed in 2 of 143 patients (1.39%) within the first week after presentation and starting prophylaxis. In both cases, it is unclear whether the thrombus had developed before or after the start of prophylaxis. One of 143 (0.69%) patients receiving prophylaxis was admitted urgently with gastrointestinal hemorrhage. Two of 143 patients (1.40%) had elective blood transfusions and procedures to manage occult gastrointestinal bleeding. No other bleeding events occurred in patients receiving prophylaxis.

CONCLUSIONS

This regimen of prophylactic antiplatelet or anticoagulant therapy appears effective in preventing VTE in nephrotic syndrome, with relatively few hemorrhagic complications.

Advances in oral anticoagulation treatment: the safety and efficacy of rivaroxaban in the prevention and treatment of thromboembolism

Arterial and venous thromboembolic diseases are a clinical and economic burden worldwide. In addition to traditional agents such as vitamin K antagonists and heparins, newer oral agents – such as the factor Xa inhibitors rivaroxaban, apixaban, and edoxaban, and the direct thrombin inhibitor dabigatran – have been shown to be effective across several indications. Rivaroxaban has been shown to have predictable pharmacokinetic and pharmacodynamic properties, including a rapid onset of action. In addition, there is no requirement for routine coagulation monitoring; and no dose adjustment is necessary for age alone, sex, or body weight. Rivaroxaban has successfully met primary efficacy and safety endpoints in large, randomized phase III trials across several indications, including: prevention of venous thromboembolism in orthopedic patients undergoing elective hip or knee replacement surgery; treatment of deep vein thrombosis and secondary prevention of deep vein thrombosis and pulmonary embolism; stroke prevention in patients with atrial fibrillation; and secondary prevention of acute coronary syndrome. Rivaroxaban and the other newer oral anticoagulants are likely to improve outcomes in the prevention and treatment of thromboembolic events, and will offer patients and physicians alternative treatment options.

Risk of venous thromboembolism in patients nursed at home or in long-term care residential facilities

Background. This study investigated the prevalence of and impact of risk factors for deep venous thrombosis (DVT) in patients with chronic diseases, bedridden or with greatly limited mobility, cared for at home or in long-term residential facilities. Methods. We enrolled 221 chronically ill patients, all over 18 years old, markedly or totally immobile, at home or in long-term care facilities. They were screened at the bedside by simplified compression ultrasound. Results. The prevalence of asymptomatic proximal DVT was 18% (95% CI 13–24%); there were no cases of symptomatic DVT or pulmonary embolism. The best model with at most four risk factors included: previous VTE, time of onset of reduced mobility, long-term residential care as opposed to home care and causes of reduced mobility. The risk of DVT for patients with reduced mobility due to cognitive impairment was about half that of patients with cognitive impairment/dementia. Conclusions. This is a first estimate of the prevalence of DVT among bedridden or low-mobility patients. Some of the risk factors that came to light, such as home care as opposed to long-term residential care and cognitive deficit as causes of reduced mobility, are not among those usually observed in acutely ill patients.

Financial implications and maternal impact of national recommendations for thromboprophylaxis: a retrospective cross-sectional analysis

BACKGROUND

Thromboembolism was a leading direct cause of maternal death in the UK in the last Saving Mothers' Lives report. National guidance proposes that all women should be risk assessed in pregnancy and after delivery.

METHODS

An audit was designed to assess the financial implication for our service. One hundred consecutive live and stillbirths were identified using the maternity database; 97 case records were obtained. Risk factors were identified and individual scores were calculated, together with the proportion that would have extended measures (low-molecular-weight heparin [LMWH], antiembolic stockings).

RESULTS

The series appeared to be representative of the UK pregnant population in terms of age, parity, body mass index, smoking and caesarean rate. Antenatally, 2.1% had a Royal College of Obstetricians and Gynaecologists (RCOG) risk score of three or more and would have been advised to have LMWH throughout pregnancy and the puerperium. Postnatally, 40.1% had an RCOG score of two or more and would have required enoxaparin for one to six weeks. The annual cost of stockings, LMWH and sharps bins approximate to GB£44,847 for every one thousand deliveries, GB£2.6 million for each life saved. About 10% of normal-weight postnatal women who achieved a vaginal birth had a risk score prompting thromboprophylaxis for at least seven days.

CONCLUSIONS

These data suggest that the current guidance might represent overmedicalization of pregnancy and that the criteria for thromboprophylaxis should be refined further.

Extended-duration rivaroxaban thromboprophylaxis in acutely ill medical patients: MAGELLAN study protocol

Patients with acute medical illnesses are at increased risk of venous thromboembolism (VTE), a significant cause of morbidity and mortality. Thromboprophylaxis is recommended in these patients but questions remain regarding the optimal duration of therapy. The aim of this study is to determine whether oral rivaroxaban is non-inferior to standard-duration (approximately 10 days) subcutaneous (s.c.) enoxaparin for the prevention of VTE in acutely ill medical patients, and whether extended-duration (approximately 5 weeks) rivaroxaban is superior to standard-duration enoxaparin. Patients aged 40 years or older and hospitalized for various acute medical illnesses with risk factors for VTE randomly receive either s.c. enoxaparin 40 mg once daily (od) for 10 ± 4 days or oral rivaroxaban 10 mg od for 35 ± 4 days. The primary efficacy outcomes are the composite of asymptomatic proximal deep vein thrombosis (DVT), symptomatic DVT, symptomatic non-fatal pulmonary embolism (PE), and VTE-related death up to day 10 + 4 and up to day 35 + 4. The primary safety outcome is the composite of treatment-emergent major bleeding and clinically relevant non-major bleeding. As of July 2010, 8,101 patients from 52 countries have been randomized. These patients have a broad range of medical conditions: approximately one-third were diagnosed with acute heart failure, just under one-third were diagnosed with acute infectious disease, and just under one-quarter were diagnosed with acute respiratory insufficiency. MAGELLAN will determine the efficacy, safety, and pharmacological profile of oral rivaroxaban for the prevention of VTE in a diverse population of medically ill patients and the potential of extended-duration therapy to reduce incidence of VTE.

Hotline update of clinical trials and registries presented at the American College of Cardiology Congress 2011

This article provides information and commentaries on trials which were presented at the Hotline and Clinical Trial Update Sessions during the Late Breaking Clinical Trial Sessions at the 60th annual meeting of the American College of Cardiology in New Orleans, USA, from 2nd April to 5th April 2011. This article gives an overview on a number of novel clinical trials in the field of cardiovascular medicine, which were presented. The comprehensive summaries have been generated from the oral presentation and the webcasts of the American College of Cardiology, similar as previously reported (Gensch et al. Clin Res Cardiol 100:1-9, 2011; Lenski et al. Clin Res Cardiol 99:679-692, 2010) and should provide the readers with the most comprehensive information of relevant publications. The data were presented by leading experts in the field with relevant positions in the trials.

Enoxaparin, effective dosage for intensive care patients: double-blinded, randomised clinical trial

Introduction

Intensive care unit (ICU) patients are predisposed to thromboembolism. Routine prophylactic anticoagulation is widely recommended. Low-molecular-weight heparins, such as enoxaparin, are increasingly used because of predictable pharmacokinetics. This study aims to determine the subcutaneous (SC) dose of enoxaparin that would give the best anti-factor Xa levels in ICU patients.

Methods

The 72 patients admitted to a mixed ICU at Odense University Hospital (OUH) in Denmark were randomised into four groups to receive 40, 50, 60, or 70 mg SC enoxaparin for a period of 24 hours. Anti-factor Xa activity (aFXa) was measured before, and at 4, 12, and 24 hours after administration. An AFXa level between 0.1 to 0.3 IU/ml was considered evidence of effective antithrombotic activity.

Results

Median peak (4 hours after administration), aFXa levels increased significantly with an increase in enoxaparin dose, from 0.13 IU/ml at 40 mg, to 0.14 IU/ml at 50 mg, 0.27 IU/ml at 60 mg, and 0.29 IU/ml at 70 mg (P = 0.002). At 12 hours after administration, median aFXa levels were still within therapeutic range for those patients who received 60 mg (P = 0.02).

Conclusions

Our study confirmed that a standard dose of 40 mg enoxaparin yielded subtherapeutic levels of aFXa in critically ill patients. Higher doses resulted in better peak aFXa levels, with a ceiling effect observed at 60 mg. The present study seems to suggest inadequate dosage as one of the possible mechanisms for the higher failure rate of enoxaparin in ICU patients.

Trial Registration

ISRCTN03037804

Prophylaxis of travel-related thrombosis in women

Travel-related thrombosis occurs in 1/6,000 individuals who fly long-haul flights. The risk is increased significantly in passengers with thrombophilia and during hormonal therapy. Pregnancy is a hypercoagulable state with 5-10-fold increase in VTE risk. Mechanisms for hypercoagulation on air are related to cabin atmospheric conditions, with immobility and flight duration playing a major role. Prophylactic measures include frequent exercise in all passengers, elastic stockings and LMWH in travelers at high risk.

An evaluation of practice pattern for venous thromboembolism prevention in Lebanese hospitals

BACKGROUND

Venous thromboembolism (VTE) is a major cause of death among hospitalized patients. Many VTE prophylaxis guidelines have been developed, including the American College of Chest Physicians (ACCP). VTE prophylaxis is required in specific patients; however, its practice is not always optimal, and often depends on the hospitals' protocols. In Lebanon, information about the appropriateness of VTE prophylaxis in health care centers is lacking.

OBJECTIVE

The primary objective of this study was to evaluate the pattern of VTE prophylaxis application, including agents, doses, duration of treatment, and route of administration, in Lebanese health care centers.

METHODS

A Lebanese multi-center, prospective, chart review study was conducted over 4 months. Data on demographics, VTE prophylaxis medication, dose, route, duration, and associated risk factors were collected by pharmacy students. The appropriateness of VTE prophylaxis was determined as per ACCP guidelines. Patients receiving VTE treatment were excluded from the study. Institutional review board (IRB) approval was obtained from each hospital center.

RESULTS

A total of 840 patients were included. Both gender groups were equally represented in the sample and the mean age was 59 +/- 19.53 years. The majority (639/840, 76.1%) of the sample were at high risk for deep venous thrombosis (DVT), and inappropriate VTE prophylaxis was reported in 35% of the low-risk group, in 70% of the moderate-risk group, and in 39% of the high-risk group (P < 0.0001). Comparing proper VTE prophylaxis practice between intensive care unit (ICU) and non-ICU patients, there was no statistical difference observed in teaching hospitals (67.2% vs. 65.5%, P = 0.312). However, in non-teaching hospitals, appropriate VTE prophylaxis practice was more prevalent in ICU than non-ICU patients (65.9% vs. 51.2%, P = 0.004). The average duration of VTE prophylaxis was less than 10 days. Missing data was a major limitation for this study, where, for instance, the duration of prophylaxis could not be accurately abstracted in half of the sample. Another limitation was the absence of laboratory results needed for clinical assessment of the regimen used.

CONCLUSION

This study reflected the importance of assessing VTE prophylaxis in Lebanese hospitals, thus, the need for implementing established guidelines to improve the overall patient safety.

[Risk of venous thromboembolism in acute medical illnesses. Part 2: Situations at risk in ambulatory, hospital and internal medicine settings]

PURPOSE

The increased risk of thromboembolism in acute medical illnesses (AMI) is difficult to assess because of the diversity of medical conditions. The first part of this review of the literature was dedicated to methods of risk analysis based on our current pathophysiological knowledge. This second part describes more specifically the risk of venous thrombosis linked to AMI in hospital, ambulatory and internal medicine settings.

CURRENT KNOWLEDGE AND KEY POINTS

The incidence of venous thromboembolism is higher in hospital than in ambulatory setting, albeit the latter remains significant. Stroke and affections leading to intensive care management represent conditions at great risk. Several mechanisms leading to a prothrombotic state have been identified, explaining the increased risk observed during relapses of pathologies specifically treated in internal medicine such as lupus erythematosus, Wegener granulomatosis, inflammatory bowel diseases and Behcet's disease.

FUTURE PROSPECTS AND PROJECTS

Next to the pathophysiological understanding of venous thrombosis, the assessment of the specific thrombogenic burden of an AMI is an additive tool to screen medical patients at high risk. This systematic review of the literature shows uncertainties towards some risk factors as bedrest or acute inflammatory response. Taking into account the methodological difficulties inherent to prospective and epidemiological studies, a meta-analysis focusing on these factors would be useful to refine prevention guidelines for venous thromboembolism in medical setting.

Safety and feasibility of subcutaneous low molecular weight heparin for cerebral venous sinus thrombosis

Background and Purpose

The effect of low molecular weight heparin (LMWH) in the management of cerebral venous thrombosis (CVT) remains unclear. The present study was performed to determine the safety and feasibility of subcutaneous LMWH, with particular attention to hemorrhagic conversions.

Methods

LMWH (nadroparin, 7,500 ICU, every 12 hours) was administered subcutaneously for 14 days to 12 patients diagnosed with CVT. Initial clinical manifestations, etiologies and the clinical courses after LMWH treatment were also evaluated. Possible hemorrhagic side effects, including aggravation of the initial hemorrhage and/or newly developed-hemorrhagic conversions were monitored by image analysis.

Results

Headaches and convulsive movements were frequent presenting symptoms for CVT. Clinical improvement was usually observed within 2 to 8 days after LMWH. Symptom stabilization was observed within 4 to 60 days. Neither clinical aggravations, nor newly developed parenchymal lesions were observed during LMWH maintenance. Associated parenchymal lesions were observed in 9 of the 12 patients, 5 of which manifested with hemorrhagic conversion, as detected by image analysis. However, no clinical and radiologic aggravation was noted in these 5 patients.

Conclusions

Our results suggest that LMWH may be safe and feasible in the management of CVT.

Venous Thromboembolism in the ICU and Reversal of Bleeding on Anticoagulants

Venous thromboembolic disease is a very common complication in the ICU. This article reviews incidence, prevention, and therapy related to venous thromboembolism, including both deep venous thrombosis and pulmonary embolism. Special diagnostic and treatment considerations in the ICU setting are highlighted. The increased use of antithrombotic agents has led to an increased number of patients who experience bleeding complications on anticoagulant therapy. This review also addresses the methods of reversing various anticoagulants.