Determinants of venous thromboembolism among hospitalizations of US adults: a multilevel analysis

Developing and validating natural language processing algorithms for radiology reports compared to ICD-10 codes for identifying venous thromboembolism in hospitalized medical patients

BACKGROUND

Identifying venous thromboembolism (VTE) from large clinical and administrative databases is important for research and quality improvement.

OBJECTIVE

To develop and validate natural language processing (NLP) algorithms to identify VTE from radiology reports among general internal medicine (GIM) inpatients.

METHODS

This cross-sectional study included GIM hospitalizations between April 1, 2010 and March 31, 2017 at 5 hospitals in Toronto, Ontario, Canada. We developed NLP algorithms to identify pulmonary embolism (PE) and deep venous thrombosis (DVT) from radiologist reports of thoracic computed tomography (CT), extremity compression ultrasound (US), and nuclear ventilation-perfusion (VQ) scans in a training dataset of 1551 hospitalizations. We compared the accuracy of our NLP algorithms, the previously-published "simpleNLP" tool, and administrative discharge diagnosis codes (ICD-10-CA) for PE and DVT to the "gold standard" manual review in a separate random sample of 4000 GIM hospitalizations.

RESULTS

Our NLP algorithms were highly accurate for identifying DVT from US, with sensitivity 0.94, positive predictive value (PPV) 0.90, and Area Under the Receiver-Operating-Characteristic Curve (AUC) 0.96; and in identifying PE from CT, with sensitivity 0.91, PPV 0.89, and AUC 0.96. Administrative diagnosis codes and the simple NLP tool were less accurate for DVT (ICD-10-CA sensitivity 0.63, PPV 0.43, AUC 0.81; simpleNLP sensitivity 0.41, PPV 0.36, AUC 0.66) and PE (ICD-10-CA sensitivity 0.83, PPV 0.70, AUC 0.91; simpleNLP sensitivity 0.89, PPV 0.62, AUC 0.92).

CONCLUSIONS

Administrative diagnosis codes are unreliable in identifying VTE in hospitalized patients. We developed highly accurate NLP algorithms to identify VTE from radiology reports in a multicentre sample and have made the algorithms freely available to the academic community with a user-friendly tool (https://lks-chart.github.io/CHARTextract-docs/08-downloads/rulesets.html#venous-thromboembolism-vte-rulesets).

Cancer and thrombosis: new insights to an old problem

Venous thromboembolism (VTE) is a common complication in patients with cancer and portends a poor prognosis. Our understanding of the underlying pathophysiology of VTE in cancer has advanced since Trousseau first described hypercoagulability in patients with malignancy and Virchow described his famous triad of thrombosis formation. Malignancy itself induces a thrombophilic state by increasing the risk of venous stasis, endothelial injury and an imbalance of pro and anti-thrombotic factors leading to a hypercoaguable state. Additional insults to this thrombotic balance are introduced by patient-specific, treatment related and tumor-specific factors. The importance of understanding the factors associated with increased thrombosis in cancer is paramount in order to adequately identify patients who will benefit from thromboprophylaxis.

Improving VTE risk assessment and prophylaxis prescribing rate in medical patients: integrating risk assessment tool into the workflow

Medical inpatients often have important risk factors for venous thromboembolism (VTE). In our institution, VTE prophylaxis in this group was underused. The main barriers identified were inattention to VTE prophylaxis, competing priorities and lack of confidence in the decision-making. We aimed to improve the rate of VTE prophylaxis use by introducing a paper-based risk assessment tool, with actionable management recommendations within the prescription chart. The rationale was that an assessment tool at the point of prescribing can reduce steps between decision-making and prescribing process, thus promoting confidence and acting as a reminder. A total of 552 prescription charts completed over a period of 29 weeks were examined during the baseline period. In the postintervention period, 871 charts completed over 40 weeks period were examined. The risk assessment tool was completed in 51% of the cases examined in the postintervention period. The introduction of the risk assessment tool was associated with a significant change in the pattern of VTE pharmacological prophylaxis use. The change occurred when the form was made highly visible and enclosed in the prescription chart. The pharmacological prophylaxis use was higher with a completed assessment form than without (mean (SD) 97.5% (7.6%) vs 70.1% (19.4%); p<0.0001). The rate of appropriate prophylaxis decision was 98.2% (SD 5.2%) with a completed assessment form, and 80.7% (SD 17.9%) when it was not used. The qualitative interviews revealed positive themes; many users found it useful, easy and convenient to use. Our data have shown that a paper-based VTE risk assessment tool placed within the prescription chart could substantially improve the rate of appropriate assessment and VTE prophylaxis implementation. This suggests that tool clearly needs to be a seamless integration into the workflow to capture users’ attention and mitigate the influence of time perception.

Risk factors for venous thromboembolism in individuals undergoing coronary artery bypass grafting

OBJECTIVE

Venous thromboembolism (VTE) can easily occur after coronary artery bypass grafting (CABG). We assessed the proportion of patients with a diagnosis of VTE after CABG and determined the associated risk factors and complications in these patients.

METHODS

We assessed all the patients included in the American College of Surgeons National Surgical Quality Improvement Program database from 2012 to 2015 who had undergone CABG. The demographic characteristics, surgical parameters, and complications were analyzed using single-factor and binary logistic regression analyses to identify the risk factors for VTE after CABG.

RESULTS

Overall, 8956 patients were identified. Postoperative VTE was found in 1.75% of these patients, with pulmonary embolism and deep vein thrombosis accounting for 0.61% and 1.28%, respectively; 0.15% of the patients had both conditions. The patients who had developed VTE had greater odds of being white and having an American Society of Anesthesiologists classification of ≥5. Multivariate analysis showed that a history of bleeding disorders, congestive heart failure, and operative time of ≥310 minutes were risk factors for the development of postoperative VTE. Patients with VTE had worse outcomes, including greater odds of returning to the operating room, hospitalization, unplanned reoperation, and readmission. The occurrence of VTE was associated with several postoperative complications, including emergency intubation, ventilator time >48 hours, pneumonia, urinary tract infection, peri- and postoperative transfusions, gradual kidney function reduction, acute kidney failure, cardiac arrest necessitating cardiopulmonary resuscitation, myocardial infarction, and septic shock.

CONCLUSIONS

The overall VTE rate after CABG has been low. However, the condition has been associated with worse 30-day postoperative outcomes and complications. The independent predictors of VTE development included a history of bleeding disorders, congestive heart failure in the 30 days before surgery, and operative time of ≥310 minutes. Understanding these risk factors should aid physicians in the decisions regarding prophylaxis and treatment.

Effects of Bariatric Surgery on Cardiovascular Disease: A Concise Update of Recent Advances

Patients with obesity often have multiple cardiovascular comorbidities as obesity is an established risk factor for various cardiovascular diseases (CVDs)—e. g., heart failure (HF), coronary artery disease (CAD), hypertension, dysrhythmia, and venous thromboembolism. In the United States, obesity is the nationwide public health issue of the day with the prevalence exceeding 30%. It has become a substantial health and financial burden to the society and national healthcare system; the direct cost accounted for 150 billion US dollars in 2014. Lifestyle interventions have been shown to be successful in the short term, however their long-term results are still equivocal likely due to modest weight reduction and high recurrence rates. For instance, the mean weight reduction in a randomized controlled trial of patients with type 2 diabetes mellitus (DM) and either overweight or obesity was 6.0% in the intensive lifestyle modification arm and 3.5% in the control arm. On the contrary, bariatric surgery is known to be the most effective in achieving substantial and long-term weight loss and can prevent the development of CVD risk factors such as DM, hypertension, and dyslipidemia. Bariatric surgery induces prompt weight loss within a few months which lasts for at least 12–18 months, with mean weight loss of ~35% (~70% loss of excess weight), lowering the risk of all-cause mortality, myocardial infarction, and stroke. Furthermore, recent studies demonstrated that bariatric surgery contributed to the reduction of acute care use for HF, CAD, and hypertension. On the other hand, it was reported that bariatric surgery may worsen the control of certain types of CVD (e.g., dysrhythmia), especially in the early postoperative period. Additionally, the notion that being overweight or obese could contribute to higher survival rate in certain populations (e.g., patients with HF)—also known as “obesity paradox”—has been repetitively documented in the past, while most recent investigations suggested that the observed paradox may be attributable to confounding factors including pre-existing comorbidities. Considering the aforementioned advances in the field, this paper reviews a series of recent studies with regard to the short-term and long-term effects of bariatric surgery on various types of CVDs.

Design and Implementation of a Comprehensive Surveillance System for Venous Thromboembolism in a Defined Region Using Electronic and Manual Approaches

BACKGROUND

Systematic surveillance for venous thromboembolism (VTE) in the United States has been recommended by several organizations. Despite adoption of electronic medical records (EMRs) by most health care providers and facilities, however, systematic surveillance for VTE is not available.

OBJECTIVES

This article develops a comprehensive, population-based surveillance strategy for VTE in a defined geographical region.

METHODS

The primary surveillance strategy combined computerized searches of the EMR with a manual review of imaging data at the Duke University Health System in Durham County, North Carolina, United States. Different strategies of searching the EMR were explored. Consolidation of results with autopsy reports (nonsearchable in the EMR) and with results from the Durham Veterans' Administration Medical Center was performed to provide a comprehensive report of new VTE from the defined region over a 2-year timeframe.

RESULTS

Monthly searches of the primary EMR missed a significant number of patients with new VTE who were identified by a separate manual search of radiology records, apparently related to delays in data entry and coding into the EMR. Comprehensive searches incorporating a location-restricted strategy were incomplete due to the assigned residence reflecting the current address and not the address at the time of event. The most comprehensive strategy omitted the geographic restriction step and identified all patients with VTE followed by manual review of individual records to remove incorrect entries (e.g., outside the surveillance time period or geographic location; no evidence for VTE). Consolidation of results from the EMR searches with results from autopsy reports and the separate facility identified additional patients not diagnosed within the Duke system.

CONCLUSION

We identified several challenges with implementing a comprehensive VTE surveillance program that could limit accuracy of the results. Improved electronic strategies are needed to cross-reference patients across multiple health systems and to minimize the need for manual review and confirmation of results.

Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE): Domain 3-Defining antithrombotic protocols

OBJECTIVES

To systematically examine the evidence for use of a specific protocol (dose, frequency, route) of selected antithrombotic drugs, in comparisons to no therapy or to other antithrombotic therapies, to reduce the risk of complications or improve outcomes in dogs and cats at risk for thrombosis.

DESIGN

Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence (LOE) and quality (Good, Fair, or Poor), and development of consensus on conclusions via a Delphi-style survey for application of the concepts to clinical practice.

SETTINGS

Academic and referral veterinary medical centers.

RESULTS

Databases searched included Medline via PubMed and CAB abstracts. Eight different antithrombotic drugs were investigated using a standardized Patient, Intervention, Comparison, Outcome (PICO) question format both for dogs and cats, including aspirin, clopidogrel, warfarin, unfractionated heparin (UFH), dalteparin, enoxaparin, fondaparinux, and rivaroxaban, generating a total of 16 worksheets. Most studies identified were experimental controlled laboratory studies in companion animals (LOE 3) with only four randomized controlled clinical trials in companion animals (LOE 1).

CONCLUSIONS

Overall, evidence-based recommendations concerning specific protocols could not be formulated for most antithrombotic drugs evaluated, either because of the wide range of dosage reported (eg, aspirin in dogs) or the lack of evidence in the current literature. However, clopidogrel administration in dogs and cats at risk of arterial thrombosis, notably in cats at risk of cardiogenic thromboembolism, is supported by the literature, and specific protocols were recommended. Comparably, aspirin should not be used as a sole antithrombotic in cats with cardiomyopathy. Using the available safety profile information contained in the literature, the panel reached consensus on suggested dosage schemes for most antithrombotics. Significant knowledge gaps were highlighted, which will hopefully drive novel research.

Validity of Using Inpatient and Outpatient Administrative Codes to Identify Acute Venous Thromboembolism: The CVRN VTE Study

BACKGROUND

Administrative data are frequently used to identify venous thromboembolism (VTE) for research and quality reporting. However, the validity of these codes, particularly in outpatients, has not been well-established.

OBJECTIVE

To determine how well International Classification of Diseases, Ninth Revision (ICD-9) codes for VTE predict chart-confirmed acute VTE in inpatient and outpatients.

PATIENTS AND METHODS

We selected 4642 adults with an incident ICD-9 diagnosis of VTE between years 2004 and 2010 from the Cardiovascular Research Network Venous Thromboembolism cohort study. Medical charts were reviewed to determine validity of events. Positive predictive values (PPVs) of ICD-9 codes were calculated as the number of chart-validated VTE events divided by the number with specific VTE codes. Analyses were stratified by VTE type [pulmonary embolism (PE), deep venous thrombosis (DVT)], code position (primary, secondary), and setting [hospital/emergency department (ED), outpatient].

RESULTS

The PPV for any diagnosis of VTE was 64.6% for hospital/ED patients and 30.9% for outpatients. Primary diagnosis codes from hospital/ED patients were more likely to represent acute VTE than secondary diagnosis codes (78.9% vs. 44.4%, P<0.001). Primary hospital/ED codes for PE and lower extremity DVT had higher PPV than for upper extremity DVT (89.1%, 74.9%, and 58.1%, respectively). Outpatient codes were poorly predictive of acute VTE: 28.0% for PE and 53.6% for lower extremity DVT.

CONCLUSIONS

ICD-9 codes for VTE obtained from outpatient encounters or from secondary diagnosis codes do not reliably reflect acute VTE. More accurate ways of identifying VTE in outpatients are needed before these codes can be adopted for research or policy purposes.

Initiating a Standard Venous Thromboembolism Prophylaxis Order Set Designed to Improve Patient Outcomes at Los Angeles County + University of Southern California

Improving patient safety is vital for all hospitals due to increasing public reporting and pay-for-performance reimbursement. Venous thromboembolism (VTE) remains a leading cause of preventable mortality accounting for 5 per cent of inpatient deaths. The purpose of this study was to outline the process of implementing standard VTE prophylactic order sets in a 600-bed academic safety net hospital and assess the resulting change in patient outcomes. Outcomes were assessed by comparing the rate that eligible inpatients receive VTE prophylaxis and the rate of preventable VTE's compared with total VTE's. From 2011 to 2015, random samples of 60 Los Angeles County+University of Southern California inpatients were generated monthly to examine compliance rates by comparing ICD-9 diagnostic codes to ordered VTE prophylaxis. All inpatient VTE's are retrospectively analyzed. Baseline-ordered VTE prophylaxis was 37 per cent in 2010. The target of 85 per cent was exceeded by the second quarter of 2012 to 2013 when compliance reached 88 per cent, a 51 per cent increase from baseline ( P < 0.01). These results suggest VTE protocols are effective though standardization across service lines is often difficult. Despite these challenges, after implementing standard order sets, we saw compliance increase significantly. Ongoing analysis to determine whether VTE rates have significantly decreased is presently underway.

Epidemiology, Risk Factors, and In-Hospital Mortality of Venous Thromboembolism in Liver Cirrhosis: A Single-Center Retrospective Observational Study

BACKGROUND

Risk of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), may be increased in liver cirrhosis. We conducted a single-center study to explore the epidemiology, risk factors, and in-hospital mortality of VTE in Chinese patients with liver cirrhosis.

MATERIAL/METHODS

All patients with liver cirrhosis who were consecutively admitted to our hospital between January 2011 and December 2013 were retrospectively included.

RESULTS

Of 2006 patients with liver cirrhosis included, 9 patients were diagnosed with or developed VTE during hospitalization, including 5 patients with a previous history of DVT, 1 patient with either a previous history of DVT or new onset of PE, and 3 patients with new onset of VTE (PE, n=1; DVT, n=2). Risk factors for VTE included a significantly higher proportion of hypertension and significantly higher red blood cells, hemoglobin, alanine aminotransferase, aspartate aminotransferase, prothrombin time (PT), international normalized ratio (INR), D-dimer, and Child-Pugh scores. The in-hospital mortality was significantly higher in patients with VTE than those without VTE (33.3% [3/9] versus 3.4% [67/1997], P<0.001).

CONCLUSIONS

VTE was observed in 0.4% of patients with liver cirrhosis during hospitalization and it significantly increased the in-hospital mortality. Elevated PT/INR aggravated the risk of VTE.