External validation of the simplified Geneva risk assessment model for hospital-associated venous thromboembolism in the Padua cohort

Risk Assessment Models for Venous Thromboembolism in Medical Inpatients

Importance

Thromboprophylaxis is recommended for medical inpatients at risk of venous thromboembolism (VTE). Risk assessment models (RAMs) have been developed to stratify VTE risk, but a prospective head-to-head comparison of validated RAMs is lacking.

Objectives

To prospectively validate an easy-to-use RAM, the simplified Geneva score, and compare its prognostic performance with previously validated RAMs.

Design, Setting, and Participants

This prospective cohort study was conducted from June 18, 2020, to January 4, 2022, with a 90-day follow-up. A total of 4205 consecutive adults admitted to the general internal medicine departments of 3 Swiss university hospitals for hospitalization for more than 24 hours due to acute illness were screened for eligibility; 1352 without therapeutic anticoagulation were included.

Exposures

At admission, items of 4 RAMs (ie, the simplified and original Geneva score, the Padua score, and the IMPROVE [International Medical Prevention Registry on Venous Thromboembolism] score) were collected. Patients were stratified into high and low VTE risk groups according to each RAM.

Main Outcomes and Measures

Symptomatic VTE within 90 days.

Results

Of 1352 medical inpatients (median age, 67 years [IQR, 54-77 years]; 762 men [55.4%]), 28 (2.1%) experienced VTE. Based on the simplified Geneva score, 854 patients (63.2%) were classified as high risk, with a 90-day VTE risk of 2.6% (n = 22; 95% CI, 1.7%-3.9%), and 498 patients (36.8%) were classified as low risk, with a 90-day VTE risk of 1.2% (n = 6; 95% CI, 0.6%-2.6%). Sensitivity of the simplified Geneva score was 78.6% (95% CI, 60.5%-89.8%) and specificity was 37.2% (95% CI, 34.6%-39.8%); the positive likelihood ratio of the simplified Geneva score was 1.25 (95% CI, 1.03-1.52) and the negative likelihood ratio was 0.58 (95% CI, 0.28-1.18). In head-to-head comparisons, sensitivity was highest for the original Geneva score (82.1%; 95% CI, 64.4%-92.1%), while specificity was highest for the IMPROVE score (70.4%; 95% CI, 67.9%-72.8%). After adjusting the VTE risk for thromboprophylaxis use and site, there was no significant difference between the high-risk and low-risk groups based on the simplified Geneva score (subhazard ratio, 2.04 [95% CI, 0.83-5.05]; P = .12) and other RAMs. Discriminative performance was poor for all RAMs, with an area under the receiver operating characteristic curve ranging from 53.8% (95% CI, 51.1%-56.5%) for the original Geneva score to 58.1% (95% CI, 55.4%-60.7%) for the simplified Geneva score.

Conclusions and Relevance

This head-to-head comparison of validated RAMs found suboptimal accuracy and prognostic performance of the simplified Geneva score and other RAMs to predict hospital-acquired VTE in medical inpatients. Clinical usefulness of existing RAMs is questionable, highlighting the need for more accurate VTE prediction strategies.

Evaluation of venous thromboembolism risk assessment models for hospital inpatients: the VTEAM evidence synthesis

Background

Pharmacological prophylaxis during hospital admission can reduce the risk of acquired blood clots (venous thromboembolism) but may cause complications, such as bleeding. Using a risk assessment model to predict the risk of blood clots could facilitate selection of patients for prophylaxis and optimise the balance of benefits, risks and costs.

Objectives

We aimed to identify validated risk assessment models and estimate their prognostic accuracy, evaluate the cost-effectiveness of different strategies for selecting hospitalised patients for prophylaxis, assess the feasibility of using efficient research methods and estimate key parameters for future research.

Design

We undertook a systematic review, decision-analytic modelling and observational cohort study conducted in accordance with Enhancing the QUAlity and Transparency Of health Research (EQUATOR) guidelines.

Setting

NHS hospitals, with primary data collection at four sites.

Participants

Medical and surgical hospital inpatients, excluding paediatric, critical care and pregnancy-related admissions.

Interventions

Prophylaxis for all patients, none and according to selected risk assessment models.

Main outcome measures

Model accuracy for predicting blood clots, lifetime costs and quality-adjusted life-years associated with alternative strategies, accuracy of efficient methods for identifying key outcomes and proportion of inpatients recommended prophylaxis using different models.

Results

We identified 24 validated risk assessment models, but low-quality heterogeneous data suggested weak accuracy for prediction of blood clots and generally high risk of bias in all studies. Decision-analytic modelling showed that pharmacological prophylaxis for all eligible is generally more cost-effective than model-based strategies for both medical and surgical inpatients, when valuing a quality-adjusted life-year at £20,000. The findings were more sensitive to uncertainties in the surgical population; strategies using risk assessment models were more cost-effective if the model was assumed to have a very high sensitivity, or the long-term risks of post-thrombotic complications were lower. Efficient methods using routine data did not accurately identify blood clots or bleeding events and several pre-specified feasibility criteria were not met. Theoretical prophylaxis rates across an inpatient cohort based on existing risk assessment models ranged from 13% to 91%.

Limitations

Existing studies may underestimate the accuracy of risk assessment models, leading to underestimation of their cost-effectiveness. The cost-effectiveness findings do not apply to patients with an increased risk of bleeding. Mechanical thromboprophylaxis options were excluded from the modelling. Primary data collection was predominately retrospective, risking case ascertainment bias.

Conclusions

Thromboprophylaxis for all patients appears to be generally more cost-effective than using a risk assessment model, in hospitalised patients at low risk of bleeding. To be cost-effective, any risk assessment model would need to be highly sensitive. Current evidence on risk assessment models is at high risk of bias and our findings should be interpreted in this context. We were unable to demonstrate the feasibility of using efficient methods to accurately detect relevant outcomes for future research.

Future work

Further research should evaluate routine prophylaxis strategies for all eligible hospitalised patients. Models that could accurately identify individuals at very low risk of blood clots (who could discontinue prophylaxis) warrant further evaluation.

Study registration

This study is registered as PROSPERO CRD42020165778 and Researchregistry5216.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR127454) and will be published in full in Health Technology Assessment; Vol. 28, No. 20. See the NIHR Funding and Awards website for further award information.

Effectiveness and cost effectiveness of pharmacological thromboprophylaxis for medical inpatients: decision analysis modelling study

Objective

To determine the balance of costs, risks, and benefits for different thromboprophylaxis strategies for medical patients during hospital admission.

Design

Decision analysis modelling study.

Setting

NHS hospitals in England.

Population

Eligible adult medical inpatients, excluding patients in critical care and pregnant women.

Interventions

Pharmacological thromboprophylaxis (low molecular weight heparin) for all medical inpatients, thromboprophylaxis for none, and thromboprophylaxis given to higher risk inpatients according to risk assessment models (Padua, Caprini, IMPROVE, Intermountain, Kucher, Geneva, and Rothberg) previously validated in medical cohorts.

Main outcome measures

Lifetime costs and quality adjusted life years (QALYs). Costs were assessed from the perspective of the NHS and Personal Social Services in England. Other outcomes assessed were incidence and treatment of venous thromboembolism, major bleeds including intracranial haemorrhage, chronic thromboembolic complications, and overall survival.

Results

Offering thromboprophylaxis to all medical inpatients had a high probability (>99%) of being the most cost effective strategy (at a threshold of £20 000 (€23 440; $25 270) per QALY) in the probabilistic sensitivity analysis, when applying performance data from the Padua risk assessment model, which was typical of that observed across several risk assessment models in a medical inpatient cohort. Thromboprophylaxis for all medical inpatients was estimated to result in 0.0552 additional QALYs (95% credible interval 0.0209 to 0.1111) while generating cost savings of £28.44 (-£47 to £105) compared with thromboprophylaxis for none. No other risk assessment model was more cost effective than thromboprophylaxis for all medical inpatients when assessed in deterministic analysis. Risk based thromboprophylaxis was found to have a high (76.6%) probability of being the most cost effective strategy only when assuming a risk assessment model with very high sensitivity is available (sensitivity 99.9% and specificity 23.7% v base case sensitivity 49.3% and specificity 73.0%).

Conclusions

Offering pharmacological thromboprophylaxis to all eligible medical inpatients appears to be the most cost effective strategy. To be cost effective, any risk assessment model would need to have a very high sensitivity resulting in widespread thromboprophylaxis in all patients except those at the very lowest risk, who could potentially avoid prophylactic anticoagulation during their hospital stay.

The Use of Risk Scores for Thromboprophylaxis in Medically Ill Patients-Rationale and Design of the RICO trial

Background  Venous thromboembolism (VTE) in hospitalized medically ill patients is a significant cause of morbidity and mortality. Guidelines suggest that VTE and bleeding risk assessment models (RAMs) should be integrated into the clinical decision-making process on thromboprophylaxis. However, poor evidence is available comparing the use of a RAM versus clinical judgement in evaluating VTE and bleeding occurrence. Methods  Reducing Important Clinical Outcomes in hospitalized medical ill patients (RICO) is a multicenter, cluster-randomized, controlled clinical trial (ClinicalTrials.gov Identifier: NCT04267718). Acutely ill patients hospitalized in Internal Medicine wards are randomized to the use of RAMs-namely the Padua Prediction Score and the International Medical Prevention Registry on Venous Thromboembolism Bleeding Score-or to clinical judgement. The primary study outcome is a composite of symptomatic objectively confirmed VTE and major bleeding at 90-day follow-up. Secondary endpoints include the evaluation of clinical outcomes at hospital discharge and the assessment of VTE prophylaxis prescription during the study period. In order to demonstrate a 50% reduction in the primary outcome in the experimental group and assuming an incidence of the primary outcome of 3.5% in the control group at 90-day; 2,844 patients across 32 centers will be included in the study. Discussion  The RICO trial is a randomized study of clinical management assessing the role of RAMs in hospitalized medical ill patients with the aim of reducing VTE and bleeding occurrence. The study has the potential to improve clinical practice since VTE still represents an important cause of morbidity and mortality in this setting.

Contemporary adequacy of thromboprophylaxis in acutely ill medical patients in Switzerland: a bi-centric prospective cohort

BACKGROUND

Venous thromboembolism is a dreaded complication of hospitalised patients, with associated morbidity, mortality and increased healthcare costs. Previous studies have shown that pharmacological thromboprophylaxis, though effective, is inadequately administered in a large proportion of medical inpatients.

STUDY AIMS

Our primary aim was to evaluate the contemporary adequacy of thromboprophylaxis in medical inpatients admitted to two Swiss hospitals (a university hospital and a regional hospital). The secondary aim was to estimate the 90-day incidence of relevant thrombotic and bleeding events.

METHODS

In this prospective cohort, patients were recruited at the University Hospital of Geneva and the Regional Hospital of Lugano between September 2020 and February 2021 and followed for 90 days for venous thromboembolism and bleeding events. The adequacy of thromboprophylaxis (pharmacological and/or mechanical) at 24h after hospital admission was evaluated according to the simplified Geneva risk score for hospital-associated venous thromboembolism.

RESULTS

Among 200 participants (100 at each site, mean age of 65 years), 57.5% were deemed at high risk of venous thromboembolism at admission. Thromboprophylaxis was adequate in 59.5% (95% CI 52.3-66.4%). Among high-risk and low-risk inpatients, thromboprophylaxis was adequate in 71.3% and 43.5%, respectively, with differences between sites. At 90 days, risks of adjudicated venous thromboembolism, major bleeding and mortality were 1.5%, 1.5% and 6.0%, respectively.

CONCLUSION

Despite the extensive literature on thromboprophylaxis, the adequacy of thromboprophylaxis has not improved and remains insufficient among medical inpatients. Implementation and evaluation of clinical decision support systems are critically needed in this field.

CLINICALTRIALS

gov number: NCT05306821.

Risk assessment models for venous thromboembolism in hospitalised adult patients: a systematic review

INTRODUCTION

Hospital-acquired thrombosis accounts for a large proportion of all venous thromboembolism (VTE), with significant morbidity and mortality. This subset of VTE can be reduced through accurate risk assessment and tailored pharmacological thromboprophylaxis. This systematic review aimed to determine the comparative accuracy of risk assessment models (RAMs) for predicting VTE in patients admitted to hospital.

METHODS

A systematic search was performed across five electronic databases (including MEDLINE, EMBASE and the Cochrane Library) from inception to February 2021. All primary validation studies were eligible if they examined the accuracy of a multivariable RAM (or scoring system) for predicting the risk of developing VTE in hospitalised inpatients. Two or more reviewers independently undertook study selection, data extraction and risk of bias assessments using the PROBAST (Prediction model Risk Of Bias ASsessment Tool) tool. We used narrative synthesis to summarise the findings.

RESULTS

Among 6355 records, we included 51 studies, comprising 24 unique validated RAMs. The majority of studies included hospital inpatients who required medical care (21 studies), were undergoing surgery (15 studies) or receiving care for trauma (4 studies). The most widely evaluated RAMs were the Caprini RAM (22 studies), Padua prediction score (16 studies), IMPROVE models (8 studies), the Geneva risk score (4 studies) and the Kucher score (4 studies). C-statistics varied markedly between studies and between models, with no one RAM performing obviously better than other models. Across all models, C-statistics were often weak (<0.7), sometimes good (0.7-0.8) and a few were excellent (>0.8). Similarly, estimates for sensitivity and specificity were highly variable. Sensitivity estimates ranged from 12.0% to 100% and specificity estimates ranged from 7.2% to 100%.

CONCLUSION

Available data suggest that RAMs have generally weak predictive accuracy for VTE. There is insufficient evidence and too much heterogeneity to recommend the use of any particular RAM.

PROSPERO REGISTRATION NUMBER

Steve Goodacre, Abdullah Pandor, Katie Sworn, Daniel Horner, Mark Clowes. A systematic review of venous thromboembolism RAMs for hospital inpatients. PROSPERO 2020 CRD42020165778. Available from https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=165778https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=165778.

Estimating the risk thresholds used by guidelines to recommend postpartum thromboprophylaxis

BACKGROUND

Guidelines for postpartum thromboprophylaxis are mostly expert based. Acceptable postpartum venous thromboembolism (VTE) risk thresholds to justify the use of thromboprophylaxis are ill defined.

OBJECTIVE

To compare the proportion of postpartum women with recommended thromboprophylaxis according to the Royal College of Obstetricians and Gynecologists (RCOG), American College of Obstetricians and Gynecologists (ACOG), and American College of Chest Physicians (ACCP) guidelines, and to estimate their threshold of risk of VTE.

METHODS

We collected maternal, obstetrical, and fetal characteristics among all women who delivered at the Geneva University Hospitals in January 2019 through medical chart review. We determined for each woman the recommended strategy of thromboprophylaxis according to each guideline. We indirectly estimated individual absolute VTE risks using a validated risk prediction model (Sultan).

RESULTS

Among 344 women (mean age 32.2 years), with 23.3% of cesarean deliveries (CD), the RCOG guideline categorized 40.1% of all deliveries, 25.4% of vaginal deliveries (VD), and 88.8% of CD as requiring thromboprophylaxis. The ACOG and ACCP guidelines, which focus on CD, categorized fewer women as high risk (35.0% and 40.0% of CD, respectively). The mean estimated risk of VTE was 0.07% in all participants, 0.12% in those with recommended thromboprophylaxis according to the RCOG, and 0.20% among women after CD with recommended thromboprophylaxis by the ACOG and ACCP guidelines.

CONCLUSIONS

Our data highlight important variations in the proportion of thromboprophylaxis recommendation between guidelines. Risk thresholds to recommend the use of heparin appear very low, and may correlate with a high, and perhaps undesirable, number needed to treat to prevent VTE events.

Underuse of medical thromboprophylaxis in mobile elderly inpatients: The SWITCO65+ cohort

BACKGROUND

Hospital-associated venous thromboembolism (HA-VTE) can be prevented by pharmacologic thromboprophylaxis. Thrombotic risk assessment models (RAMs) are essential tools to improve inadequately prescribed thromboprophylaxis. Among cases of HA-VTE, our study objectives are to explore the classifications of available thrombosis RAMs, the adequacy of thromboprophylaxis and risk factors for inadequate thromboprophylaxis.

METHODS

We identified cases of HA-VTE occurring during medical hospitalizations within a multicenter Swiss venous thromboembolism (VTE) cohort (2009-2013). We calculated the proportion of VTE cases deemed at high risk with 4 VTE RAMs (Geneva, Simplified Geneva, Padua, and Improve) and the adequacy of administered pharmacologic thromboprophylaxis, and explored risk factors for underprescription of thromboprophylaxis in high-risk inpatients.

RESULTS

Among 66 medical inpatients with HA-VTE, 60.6% had pulmonary embolism. The sensitivities of the Geneva, Simplified Geneva, Padua, and Improve RAMs were 86.4%, 80.3%, 72.7%, and 57.6%, respectively. The proportion of inadequate thromboprophylaxis was high, as 62.5%-71.1% of high-risk inpatients had not received it. Among the high-risk group according to the Simplified Geneva RAM, absence of immobilization was the only variable significantly associated with an inadequate use of thromboprophylaxis (odds ratio, 3.59; 95% confidence interval, 1.08-11.88).

CONCLUSIONS

We found a dramatically high proportion of inadequate medical thromboprophylaxis among inpatients who suffered from HA-VTE. This reinforces the need for global and local quality-improvement efforts to promote adequate use of thromboprophylaxis in elderly inpatients. Mobility may favor the underuse of thromboprophylaxis, and clinicians should stay alert to other thrombotic risk factors in mobile inpatients.

DVT and Pulmonary Embolism Following Knee Arthroscopy: The Role of Genetic Predisposition and Autoimmune Antibodies: A Report of 3 Cases

Deep vein thrombosis (DVT) after arthroscopy has been considered a rare event; however, recent studies using ultrasound and venography have shown that the incidence of DVTs is underestimated. CASES:: This report describes 3 patients with DVT and/or PE after knee arthroscopy who were attributed to a genetic predisposition of hypercoagulability unknown to the patient and surgeon. CONCLUSIONS:: Genetic predisposition and autoimmune antibodies may play a role in the development of DVT after knee arthroscopy. We recommend focused questions regarding family history be added to the standard DVT/PE preoperative questionnaire.

Venous thromboembolism (VTE) risk stratification in general medical patients at an academic medical center

Hospital-acquired venous thromboembolism (VTE) is still a concern for general medical patients. Pharmacologic prophylaxis can reduce VTE incidence, but there is the potential for adverse effects. Therefore, determining which patients should receive VTE prophylaxis via risk scoring tools is essential. Limited evidence exists for the ideal venous thromboembolism risk assessment model (RAM) in hospitalized medical patients, as compared to other hospitalized patient subgroups such as surgical patients. The primary objective was to investigate the utilization and appropriateness of our institution-based VTE RAM and comparison to the Padua Prediction Score (PPS). This would allow for a gauge of provider risk assessment accuracy as well as appropriate predictive potential of the PPS or whether an alternative to the PPS should be considered. A total of 330 adult general medicine patients were included in this retrospective chart review. When compared to our institution-based VTE RAM, providers predominately stratified patients at a higher VTE risk than the institution-based VTE RAM. VTE incidence was 0.3%, which was lower than predicted. Significant discordance exists between providers' VTE risk assessment and that predicted by RAMs. Our institution-based VTE RAM appears comparable to PPS; however, it was not being utilized by providers, resulting in potentially unnecessary use of pharmacologic prophylaxis. The most appropriate venous thromboembolism risk assessment model for general medicine patients is undetermined. Our providers generally assess patients as moderate or high VTE risk, despite our institution-based RAM which typically recommends a lower risk category than provider selection. Because of provider risk assessment, more patients received pharmacologic VTE prophylaxis than would have been recommended by the RAM, which might correlate to the low incidence of VTE which was < 0.5%, although bleeding complications were not assessed in this study. A prospective study utilizing the Padua Prediction Score (or similar RAM) in general medicine patients is warranted in order to decipher the best method of predicting VTE risk.