External Validation of the Risk Assessment Model of the International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) for Medical Patients in a Tertiary Health System

Abstract

BackgroundHospitalized medical patients are at risk for venous thromboembolism (VTE). Universal application of pharmacological thromboprophylaxis has the potential to place a large number of patients at increased bleeding risk. In this study, we aimed to externally validate the International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) VTE risk assessment model in a hospitalized general medical population.Methods and ResultsWe identified medical discharges that met the IMPROVE protocol. Cases were defined as hospital‐acquired VTE and confirmed by diagnostic study within 90 days of index hospitalization; matched controls were also identified. Risk factors for VTE were based on the IMPROVE risk assessment model (aged >60 years, prior VTE, intensive care unit or coronary care unit stay, lower limb paralysis, immobility, known thrombophilia, and cancer) and were measured and assessed. A total of 19 217 patients met the inclusion criteria. The overall VTE event rate was 0.7%. The IMPROVE risk assessment model identified 2 groups of the cohort by VTE incidence rate: The low‐risk group had a VTE event rate of 0.42 (95% CI 0.31 to 0.53), corresponding to a score of 0 to 2, and the at‐risk group had a VTE event rate of 1.29 (95% CI 1.01 to 1.57), corresponding to a score of ≥3. Low‐risk status for VTE encompassed 68% of the patient cohort. The area under the receiver operating characteristic curve was 0.702, which was in line with the derivation cohort findings.ConclusionsThe IMPROVE VTE risk assessment model validation cohort revealed good discrimination and calibration for both the overall VTE risk model and the identification of low‐risk and at‐risk medical patient groups, using a risk score of ≥3. More than two thirds of the entire cohort had a score ≤2.

Characterization of Venous Thromboembolism Risk in Medical Inpatients Using Different Clinical Risk Assessment Models

“…3 Notably, the investigators externally validated the IMPROVE associative risk assessment model in 2 additional databases, both of which showed accurate identification of patients at sufficiently low risk of VTE to omit thromboprophylaxis. 11,12 The primary objective of the current study was to compare the proportion of patients considered at high risk for VTE (and Can J Hosp Pharm. 2016;69(5):454-9 d'événements thromboemboliques chez les patients médicaux hospitalisés pourrait réduire l'utilisation de la thromboprophylaxie médicamenteuse, qui pourrait passer de 80 % à aussi peu que 7 %.…”

Validation of Risk Assessment Models of Venous Thromboembolism in Hospitalized Medical Patients

“…[1] While several risk assessment models exist for venous thromboembolism in medical patients, [2][3][4][5] published risk assessment models have limited generalizability and validation. [6] Although a few recent studies have validated existing risk assessment models, [5,7,8] these validation efforts lacked external validation, [5] have had limited external validation, [9] or have had largescale external validation with a risk assessment model that has limitations in predicting at-admission venous thromboembolism risk. [7,8] Additional largescale, external validation studies are important to help confirm or refute the accuracy of available risk assessment models, especially during hospital admission and based on detailed clinical data, as the performance of existing risk assessment models has been moderate at best in this setting.…”

“…Given that a patient's risk status may change during the course of hospitalization and especially to determine a patient's continued venous thromboembolism risk after hospital discharge, the original IMPROVE study also developed an associative model, including the additional risk factors of immobility, lower limb paralysis, and intensive care unit stay, which yielded an improved c-statistic of 0.69 [4]. Recent large-scale external validation studies of the associative IMPROVE risk assessment model have shown good calibration and discrimination, suggesting that the IMPROVE associative venous thromboembolism risk assessment model may reliably stratify venous thromboembolism risk,[7,8, 16] and this model has been incorporated into a recent large multicenter, multinational trial of post-hospital discharge thromboprophylaxis, the MARINER trial (ClinicalTrials.gov Identifier: NCT02111564). However, the main limitation of the IMPROVE associative risk assessment model is incomplete validation during hospital admission.…”

Extended Venous Thromboembolism Prophylaxis in Medically Ill Patients

“…It will evaluate postdischarge use of rivaroxaban 10 mg/day compared with placebo for 45 days in a selected group of patients at high risk for VTE. Eligible patients will have a D‐dimer concentration 2 or more times the ULN, plus elevated risk as demonstrated by a modified IMPROVE VTE risk score of 2 or 3, or with IMPROVE VTE risk scores of 4 or higher regardless of D‐dimer concentrations . The trial will enroll ~8000 patients; results are expected in May 2018.…”

“…Current recommendations are limited to the acute inpatient period of care and do not support extending thromboprophylaxis beyond the period of immobilization or acute hospital stay. The IMPROVE VTE (International Medical Prevention Registry on Venous Thromboembolism) risk score is also widely used in clinical practice to identify medically ill patients at low and high risk for VTE within 90 days (Table ) . Patients with a score of 0–2 are considered to be at low risk; those with a score higher than 2 have a 9‐ to 23‐fold increased risk for developing VTE.…”