Validation of Risk Assessment Models of Venous Thromboembolism in Hospitalized Medical Patients.
Patients hospitalized for acute medical illness are at increased risk for venous thromboembolism. Although risk assessment is recommended and several at-admission risk assessment models have been developed, these have not been adequately derived or externally validated. Therefore, an optimal approach to evaluate venous thromboembolism risk in medical patients is not known.



We conducted an external validation study of existing venous thromboembolism risk assessment models using data collected on 63,548 hospitalized medical patients as part of the Michigan Hospital Medicine Safety (HMS) Consortium. For each patient, cumulative venous thromboembolism risk scores and risk categories were calculated. Cox regression models were used to quantify the association between venous thromboembolism events and assigned risk categories. Model discrimination was assessed using Harrell's C-index.



Venous thromboembolism incidence in hospitalized medical patients is low (1%). Although existing risk assessment models demonstrate good calibration (hazard ratios for "at-risk" range 2.97-3.59), model discrimination is generally poor for all risk assessment models (C-index range 0.58-0.64).



The performance of several existing risk assessment models for predicting venous thromboembolism among acutely ill, hospitalized medical patients at admission is limited. Given the low venous thromboembolism incidence in this nonsurgical patient population, careful consideration of how best to utilize existing venous thromboembolism risk assessment models is necessary, and further development and validation of novel venous thromboembolism risk assessment models for this patient population may be warranted.
The Michigan Hospital Medicine Safety Consortium Data Coordinating Center, Ann Arbor; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor. Electronic address: mtgreene@med.umich.edu.
M Todd
MT
Greene
Hofstra North Shore-LIJ School of Medicine, Manhasset, NY.
Alex C
AC
Spyropoulos
The Michigan Hospital Medicine Safety Consortium Data Coordinating Center, Ann Arbor; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor; VA Ann Arbor Health Care System, Mich.
Vineet
V
Chopra
The Michigan Hospital Medicine Safety Consortium Data Coordinating Center, Ann Arbor; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor.
Paul J
PJ
Grant
Hurley Medical Center, Flint, Mich.
Scott
S
Kaatz
The Michigan Hospital Medicine Safety Consortium Data Coordinating Center, Ann Arbor; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor; VA Ann Arbor Health Care System, Mich.
Steven J
SJ
Bernstein
The Michigan Hospital Medicine Safety Consortium Data Coordinating Center, Ann Arbor; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor.
Scott A
SA
Flanders
D000368:Aged; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008824:Michigan / Q000453:epidemiology; D015233:Models, Statistical; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D054556:Venous Thromboembolism / Q000453:epidemiology / Q000209:etiology*
Venous thromboembolism