Symptoms and clinical relevance: A dilemma for clinical trials on prevention of venous thromboembolism

Perioperative Prevention of Venous Thromboembolism in Abdominal Surgery Patients Based on the Caprini or the Padua Risk Score-A Single Centre Prospective Observational Study

Surgical patients should receive perioperative thromboprophylaxis based on risk assessment, and the Caprini score is validated for this purpose. Whether the Padua score, originally devised for medical patients, can be useful in surgical patients remains to be fully clarified. This study aimed to evaluate perioperative thromboprophylaxis based on the Caprini or the Padua score in elective abdominal surgery. A total of 223 patients undergoing elective abdominal surgery for malignant or benign disease were prospectively evaluated. The patients were divided into two groups in which thromboprophylaxis was prescribed according to either the Caprini score (n = 122) or the Padua score (n = 101). Patients with high-risk scores in both groups received nadroparin. The alternate risk score in each group was calculated for evaluation purposes only. During a 3-month follow-up, we assessed patients for symptomatic venous thromboembolism (VTE), bleeding, or mortality. In the Caprini score group, 87 patients (71%) had a high risk for VTE (≥5 points), while 38 patients (38%) had a high risk for VTE (≥4 points) in the Padua score group; p < 0.00001. The overall correlation between the Caprini and Padua scores was moderate (r= 0.619), with 85 patients having high Caprini and discordant Padua scores. Ten patients died during follow-up (4.5%), and five developed non-fatal symptomatic VTE (2.2%). Among the five major bleeding incidents recorded (1.8%), two cases were possibly associated with pharmacological thromboprophylaxis. The incidence of adverse outcomes did not differ between the two groups. The odds ratio for adverse outcomes was significantly higher with a high Caprini or Padua risk score, malignant disease, age ≥65 years, and active smoking. We found no significant differences in adverse outcomes between abdominal surgical patients who received perioperative thromboprophylaxis based on either the Caprini or the Padua risk score. However, a discordant Padua score was noted in almost 40% of patients who had a high Caprini score, suggesting that the latter may be more sensitive than the Padua score in surgical patients.

A modeling approach to derive baseline risk estimates for GRADE recommendations:Concepts, development, and results of its application to the American Society of Hematology 2019 guidelines on prevention of venous thromboembolism in surgical hospitalized patients

OBJECTIVE

The goal of this study was to develop an approach that can be used where baseline risk estimates that are directly applicable to prioritized patient-important outcomes are not available from published studies.

STUDY DESIGN

The McMaster University GRADE Centre and the ASH guideline panel for the prevention of VTE in surgical patients developed a modeling approach based on explicit assumptions about the distribution of symptoms, anatomical location, and severity of VTE events.

RESULTS

We applied the approach to derive modeled estimates of baseline risk. These estimates were used to calculated absolute measures of anticipated effects that informed the discussion of the evidence and the formulation of 30 guideline recommendations.

CONCLUSIONS

Our approach can assist guideline developers facing a lack of information about baseline risk estimates that directly apply to outcomes of interest. The use of modeled estimates increases transparency in the process and makes the baseline risk used by guideline experts explicit during their decision-making.

Thromboembolism in Heart Failure Patients in Sinus Rhythm: Epidemiology, Pathophysiology, Clinical Trials, and Future Direction

Despite advances in medical and device therapy, patients with heart failure remain at high risk for morbidity and mortality. Experimental and clinical studies have shown an association between heart failure and a hypercoagulable state, and that patients with heart failure experience an increased incidence of stroke and other thromboembolic events, regardless of whether they are in atrial fibrillation. Although oral anticoagulation is recommended when atrial fibrillation is present, the benefits of this therapy in patients with heart failure in sinus rhythm are uncertain. Older randomized controlled trials comparing warfarin with antiplatelet therapy were, for the most part, underpowered and failed to show convincing benefits of warfarin therapy in this population. Several recent studies that assessed the effects of low-dose direct-acting oral anticoagulant therapy in patients with coronary artery disease in sinus rhythm either included or specifically targeted patients with heart failure. Post hoc analysis of their results showed that this treatment strategy was associated with improved outcomes in patients with acute coronary syndrome or stable coronary artery disease and also a significant reduction in thromboembolic events, including ischemic stroke. This review presents the rationale for anticoagulant therapy in patients with heart failure in sinus rhythm, discusses gaps in our knowledge base, offers suggestions for when anticoagulation might be considered, and identifies potential directions for future research.

Association Between Asymptomatic Proximal Deep Vein Thrombosis and Mortality in Acutely Ill Medical Patients

Background Asymptomatic proximal deep vein thrombosis (DVT) is an end point frequently used to evaluate the efficacy of anticoagulant thromboprophylaxis in medical patients. Recently, the clinical relevance of asymptomatic DVT has been challenged. Methods and Results The objective of this study was to evaluate the relationship between asymptomatic proximal DVT and all-cause mortality (ACM) using a cohort analysis of a randomized trial for the prevention of venous thromboembolism (VTE) in acutely ill medical patients. Patients who received at least 1 dose of study drug and had an adequate compression ultrasound examination of the legs on either day 10 or day 35 were categorized into 1 of 3 cohorts: no VTE, asymptomatic proximal DVT, or symptomatic DVT. Cox proportional hazards model, with adjustment for significant independent predictors of mortality, were used to compare the incidences of ACM. Of the 7036 patients, 6776 had no VTE, 236 had asymptomatic DVT, and 24 had symptomatic VTE. The incidence of ACM was 4.8% in patients without VTE. Both asymptomatic proximal DVT (mortality, 11.4%; hazard ratio [HR], 2.31; 95% CI, 1.52-3.51; P<0.0001) and symptomatic VTE (mortality, 29.2%; HR, 9.42; 95% CI, 4.18-21.20; P<0.0001) were independently associated with significant increases in ACM. The analysis was post hoc, and ultrasound results were not available for all patients. Adjustment for baseline variables significantly associated with ACM may not fully compensate for differences. Conclusions Asymptomatic proximal DVT is associated with higher ACM than no VTE and remains a relevant end point to evaluate the efficacy of anticoagulant thromboprophylaxis in medical patients. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00571649.

Mandatory contrast-enhanced venography to detect deep-vein thrombosis (DVT) in studies of DVT prophylaxis: upsides and downsides

The introduction of venography into patient care was a major advance because it was the first accurate method for the diagnosis of DVT. Compression ultrasound has since become the preferred test for patients with suspected DVT because, unlike venography, it is simple, non-invasive and widely available. Venography has facilitated the development and approval of new anticoagulants and remains widely used as an efficacy outcome in trials of venous thromboembolism prevention. Most thrombi detected by screening venography are, however, small and unimportant for patients. In order to calculate the trade-off between an asymptomatic thrombus and a bleed we require an estimate of the number of asymptomatic thrombi that must be prevented to avoid a patient-important thrombus. A credible estimate of this ratio is not available. Therefore when used as a measure of efficacy in trials of thromboprophylaxis, venography has limitations for comparing the relative effects of alternative antithrombotic agents on outcomes important to patients.

Non-vitamin K antagonist oral anticoagulants and heart failure

Thromboembolism contributes to morbidity and mortality in patients with heart failure (HF), and atrial fibrillation (AF) is one of the main factors promoting this complication. As they share many risk factors, HF and AF frequently coexist, and patients with both conditions are at a particularly high risk of thromboembolism. Non-vitamin K antagonist oral anticoagulants (NOACs) are direct antagonists of thrombin (dabigatran) and factor Xa (rivaroxaban, apixaban and edoxaban), and were designed to overcome the limitations of vitamin K antagonists. Compared with warfarin in non-valvular AF, NOACs demonstrated non-inferiority with better safety, most particularly for intracranial haemorrhages. Therefore, the European Society of Cardiology guidelines recommend NOACs for most patients with non-valvular AF. Subgroups of patients with both AF and HF from the pivotal studies investigating the safety and efficacy of NOACs have been analysed and, for each NOAC, results were similar to those of the total analysis population. A recent meta-analysis of these subgroups has confirmed the better efficacy and safety of NOACs in patients with AF and HF - particularly the 41% decrease in the incidence of intracranial haemorrhages. The prothrombotic state associated with HF suggests that patients with HF in sinus rhythm could also benefit from treatment with NOACs. However, in the absence of clinical trial data supporting this indication, current guidelines do not recommend anticoagulant treatment of patients with HF in sinus rhythm. In conclusion, recent analyses of pivotal studies support the use of NOACs in accordance with their indications in HF patients with non-valvular AF.