The Prevention of Venous Thromboembolism in Surgical Patients

Risk factors for patients with acute hospital-acquired symptomatic pulmonary thromboembolism

This study aimed to identify independent risk factors for acute hospital-acquired symptomatic pulmonary embolism (HA-SPE) by comparing the clinical data of HA-SPE and acute nonhospital-acquired symptomatic pulmonary embolism (NHA-SPE). A total of 292 patients were included in the analysis and divided into two groups: 191 patients had acute NHA-SPE, and 101 patients had acute HA-SPE. The average age of these 292 patients was 63.2 years, and the sample included 145 males. Multivariate analysis showed that malignant tumour (OR, 3.811; 95% CI [1.914-7.586], P = 0.000), recent surgery (OR, 7.310; 95% CI 3.392-15.755], P = 0.000), previous VTE (OR, 5.973; 95% CI 2.194 16.262], P = 0. 000), and the length of stay (LOS) (OR, 1.075; 95% CI [1.040-1.111], P = 0.000) were independent risk factors for acute HA-AEP. The c-statistic for this model was 0.758 (95% CI [0.698-0.800], P < 0.0001). The K-M curve showed that the hazard ratio (HR) of the HA group to the NHA group in all-cause mortality was 3.807 (95% CI [1.987, 7.295], P = 0.0061). Strengthening the prevention and control of patients with these risk factors may reduce the incidence of acute HA-SPE.

Comparison of Chemical and Mechanical Prophylaxis of Venous Thromboembolism in Non-surgical Mechanically Ventilated Patients

To compare the efficacy of mechanical and chemical prophylaxis in non-surgically mechanically ventilated patients in terms of reduction in mortality and length of hospital stay.

A total of 200 patients admitted to intensive care units (ICUs) were recruited retrospectively. Half participants received mechanical prophylaxis and half received chemical prophylaxis. Patients with medical diseases with age 18 years or above, both genders, Pakistani nationals, receiving mechanical ventilation for more than 48 hours or receiving subcutaneous low molecular weight (LMW) heparin or subcutaneous unfractionated heparin were included. Cases who undergone surgery and were then admitted to ICU, those who received both mechanical and chemical therapies, and patients who received anticoagulant treatment before admission to ICU were excluded from the study. The patient’s age, gender, length of stay in ICU, and mortality were recorded in each group. Chi-square test was used to compare categorical data and Student t-test for continuous variables.

The mean age was 55.51±8.37 years. The males were 108(54%) and females were 92(46%). The mortality rate was higher in the mechanical prophylaxis group (49%) than chemical (31%) statistically significantly (P=0.014). Similarly, the length of hospital stay was also higher in the mechanical prophylaxis group (7.27±0.897 days) than chemical (6.67±1.045) statistically (P<0.001).

Chemical prophylaxis can reduce mortality and length of hospital stay more effectively than mechanical prophylaxis in ICUs admitted patients.

A Machine Learning Approach to Predict Deep Venous Thrombosis Among Hospitalized Patients

Deep venous thrombosis (DVT) is associated with significant morbidity, mortality, and increased healthcare costs. Standard scoring systems for DVT risk stratification often provide insufficient stratification of hospitalized patients and are unable to accurately predict which inpatients are most likely to present with DVT. There is a continued need for tools which can predict DVT in hospitalized patients. We performed a retrospective study on a database collected from a large academic hospital, comprised of 99,237 total general ward or ICU patients, 2,378 of whom experienced a DVT during their hospital stay. Gradient boosted machine learning algorithms were developed to predict a patient's risk of developing DVT at 12- and 24-hour windows prior to onset. The primary outcome of interest was diagnosis of in-hospital DVT. The machine learning predictors obtained AUROCs of 0.83 and 0.85 for DVT risk prediction on hospitalized patients at 12- and 24-hour windows, respectively. At both 12 and 24 hours before DVT onset, the most important features for prediction of DVT were cancer history, VTE history, and internal normalized ratio (INR). Improved risk stratification may prevent unnecessary invasive testing in patients for whom DVT cannot be ruled out using existing methods. Improved risk stratification may also allow for more targeted use of prophylactic anticoagulants, as well as earlier diagnosis and treatment, preventing the development of pulmonary emboli and other sequelae of DVT.

Impaired contraction of blood clots precedes and predicts postoperative venous thromboembolism

Deep vein thrombosis (DVT) is a common but unpredictable complication of surgical interventions. To reveal an association between the blood clot contraction (retraction) and the incidence of postoperative venous thrombosis, 78 patients with brain tumors that were operated on were studied, of which 23 (29%) were diagnosed with postoperative DVT. A clot contraction assay, along with other hemostatic and hematologic tests, was performed 1–3 days before the surgery and on the 1st day and 5–7th days after the surgery. On the 1st postoperative day, clot contraction was significantly suppressed in patients who subsequently developed DVT, compared to the patients without DVT. Importantly, this difference was observed at least 5 days before DVT had developed. The weakening of contraction on the 1st postoperative day was more pronounced in the DVT patients with malignant versus benign brain tumors, atherosclerosis, hypertension, as well as in patients receiving steroids before and during the operation. These results indicate that impaired clot contraction in the postoperative period is associated with imminent DVT, suggesting that it is a prothrombotic risk factor and promotional mechanism. The clot contraction assay has a predictive value in assessing the threat of postoperative thrombosis in patients with benign and malignant brain tumors.

Association of Acute Venous Thromboembolism With In-Hospital Outcomes of Coronary Artery Bypass Graft Surgery

Background

While venous thromboembolism (VTE) prophylaxis is a strong recommendation after most surgeries, it is controversial in cardiac surgeries such as coronary artery bypass grafting (CABG), because of perceived low VTE incidence and increased bleeding risk. Prior studies may not have been adequately powered to study outcomes of VTE in this population. We sought to investigate the postoperative incidence and outcomes of CABG patients using a large national inpatient database.

Methods and Results

We utilized the 2013 to 2014 National Inpatient Sample to identify all patients >18 years of age who underwent CABG (without concomitant valvular procedures), and had VTE during the hospital stay. We then compared clinically relevant outcomes in patients with and without VTE. We identified 331 950 CABG procedures. Of these, 1.3% (n=4205) had VTE. Patients with VTE were more likely to be older (mean 67.2±10.4 years versus 65.2±10.4 years, P<0.001). VTE was associated with higher incidence of inpatient mortality (6.8% versus 1.7%; adjusted odds ratio 1.92 [95% CI 1.40–2.65]; P<0.001) and complications. VTE was also associated with higher cost (mean±SE $81 995±$923 versus $48 909±$55) and longer length of stay (mean±SE 17.06±0.16 days versus 8.52±0.01 days).

Conclusions

Our analysis of >330 000 CABG procedures suggests that while postoperative VTE after CABG is rare, it is associated with increased morbidity and mortality. Randomized controlled trials are needed to identify optimal strategies for VTE prophylaxis in these patients.

Interventions for implementation of thromboprophylaxis in hospitalized patients at risk for venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a leading cause of morbidity and mortality in hospitalized patients. While numerous randomized controlled trials (RCTs) have shown that the appropriate use of thromboprophylaxis in hospitalized patients at risk for VTE is safe, effective, and cost-effective, thromboprophylaxis remains underused or inappropriately used. Our previous review suggested that system-wide interventions, such as education, alerts, and multifaceted interventions were more effective at improving the prescribing of thromboprophylaxis than relying on individual providers' behaviors. However, 47 of the 55 included studies in our previous review were observational in design. Thus, an update to our systematic review, focused on the higher level of evidence of RCTs only, was warranted.

OBJECTIVES

To assess the effects of system-wide interventions designed to increase the implementation of thromboprophylaxis and decrease the incidence of VTE in hospitalized adult medical and surgical patients at risk for VTE, focusing on RCTs only.

SEARCH METHODS

Our research librarian conducted a systematic literature search of MEDLINE Ovid, and subsequently translated it to CENTRAL, PubMed, Embase Ovid, BIOSIS Previews Ovid, CINAHL, Web of Science, the Database of Abstracts of Reviews of Effects (DARE; in the Cochrane Library), NHS Economic Evaluation Database (EED; in the Cochrane Library), LILACS, and clinicaltrials.gov from inception to 7 January 2017. We also screened reference lists of relevant review articles. We identified 12,920 potentially relevant records.

SELECTION CRITERIA

We included all types of RCTs, with random or quasi-random methods of allocation of interventions, which either randomized individuals (e.g. parallel group, cross-over, or factorial design RCTs), or groups of individuals (cluster RCTs (CRTs)), which aimed to increase the use of prophylaxis or appropriate prophylaxis, or decrease the occurrence of VTE in hospitalized adult patients. We excluded observational studies, studies in which the intervention was simply distribution of published guidelines, and studies whose interventions were not clearly described. Studies could be in any language.

DATA COLLECTION AND ANALYSIS

We collected data on the following outcomes: the number of participants who received prophylaxis or appropriate prophylaxis (as defined by study authors), the occurrence of any VTE (symptomatic or asymptomatic), mortality, and safety outcomes, such as bleeding. We categorized the interventions into alerts (computer or human alerts), multifaceted interventions (combination of interventions that could include an alert component), educational interventions (e.g. grand rounds, courses), and preprinted orders (written predefined orders completed by the physician on paper or electronically). We meta-analyzed data across RCTs using a random-effects model. For CRTs, we pooled effect estimates (risk difference (RD) and risk ratio (RR), with 95% confidence interval (CI), adjusted for clustering, when possible. We pooled results if three or more trials were available for a particular intervention. We assessed the certainty of the evidence according to the GRADE approach.

MAIN RESULTS

From the 12,920 records identified by our search, we included 13 RCTs (N = 35,997 participants) in our qualitative analysis and 11 RCTs (N = 33,207 participants) in our meta-analyses.

PRIMARY OUTCOME

Alerts were associated with an increase in the proportion of participants who received prophylaxis (RD 21%, 95% CI 15% to 27%; three studies; 5057 participants; I² = 75%; low-certainty evidence). The substantial statistical heterogeneity may be in part explained by patient types, type of hospital, and type of alert. Subgroup analyses were not feasible due to the small number of studies included in the meta-analysis.Multifaceted interventions were associated with a small increase in the proportion of participants who received prophylaxis (cluster-adjusted RD 4%, 95% CI 2% to 6%; five studies; 9198 participants; I² = 0%; moderate-certainty evidence). Multifaceted interventions with an alert component were found to be more effective than multifaceted interventions that did not include an alert, although there were not enough studies to conduct a pooled analysis.

SECONDARY OUTCOMES

Alerts were associated with an increase in the proportion of participants who received appropriate prophylaxis (RD 16%, 95% CI 12% to 20%; three studies; 1820 participants; I² = 0; moderate-certainty evidence). Alerts were also associated with a reduction in the rate of symptomatic VTE at three months (RR 64%, 95% CI 47% to 86%; three studies; 5353 participants; I² = 15%; low-certainty evidence). Computer alerts were associated with a reduction in the rate of symptomatic VTE, although there were not enough studies to pool computer alerts and human alerts results separately.

AUTHORS' CONCLUSIONS

We reviewed RCTs that implemented a variety of system-wide strategies aimed at improving thromboprophylaxis in hospitalized patients. We found increased prescription of prophylaxis associated with alerts and multifaceted interventions, and increased prescription of appropriate prophylaxis associated with alerts. While multifaceted interventions were found to be less effective than alerts, a multifaceted intervention with an alert was more effective than one without an alert. Alerts, particularly computer alerts, were associated with a reduction in symptomatic VTE at three months, although there were not enough studies to pool computer alerts and human alerts results separately.Our analysis was underpowered to assess the effect on mortality and safety outcomes, such as bleeding.The incomplete reporting of relevant study design features did not allow complete assessment of the certainty of the evidence. However, the certainty of the evidence for improvement in outcomes was judged to be better than for our previous review (low- to moderate-certainty evidence, compared to very low-certainty evidence for most outcomes). The results of our updated review will help physicians, hospital administrators, and policy makers make practical decisions about adopting specific system-wide measures to improve prescription of thromboprophylaxis, and ultimately prevent VTE in hospitalized patients.