Prediction score identified critically ill patients at increased risk for VTE

The score assigned points based on central venous catheterization, immobilization, history of venous thromboembolism (VTE), mechanical ventilation, hemoglobin levels during hospitalization, and platelet count at admission.

A prediction score helped to identify patients in the ICU who were at increased risk for in-hospital symptomatic venous thromboembolism (VTE).

Researchers at a five-hospital health system in Detroit retrospectively reviewed records for all adult patients admitted to any ICU (total of 264 beds) between January 2015 and March 2018. They defined in-hospital symptomatic VTE as acute deep venous thrombosis of the upper or lower extremities, pulmonary embolism, or both diagnosed more than 24 hours after ICU admission and confirmed by ultrasound, CT, or nuclear medicine imaging. They derived a prediction score (the ICU-VTE score) from independent risk factors identified using multivariable logistic regression. Results were published on March 13 by Critical Care Medicine.

A total of 37,050 patients met the eligibility criteria, and 79% received VTE pharmacoprophylaxis. Overall, 529 patients (1.4%) developed symptomatic VTE. The median interval from ICU admission to VTE diagnosis was six days, and most events occurred within the first two weeks of ICU admission. The ICU-VTE score was derived from six independent predictors: central venous catheterization (5 points), immobilization for four days or more (4 points), history of VTE (4 points), mechanical ventilation (2 points), lowest hemoglobin level during hospitalization greater than or equal to 9 g/dL (2 points), and platelet count at admission greater than 250,000 cells/µL (1 point). ICU-VTE scores ranged from 0 to 18 points and were divided into three categories of VTE risk. Patients with a score of 0 to 8 (76% of the sample) had a low (0.3%) risk of VTE, those with a score of 9 to 14 (22%) had an intermediate (3.6%) risk, and those with a score of 15 to 18 (2%) had a high (17.7%) risk. In an internal validation cohort of 11,083 patients, the C-statistic (a measure of accuracy) of the score was 0.86 (95% CI, 0.83 to 0.88), indicating high predictive accuracy and similarity to the entire cohort.

Among other limitations, the study only counted symptomatic VTE and did not include data on VTE events occurring after hospitalization, the study authors said. They added that they did not look at ICU disease severity scores, vasopressor use, or serial prothrombin times as potential risk factors during hospitalization.

The ICU-VTE score can be applied to the full spectrum of medical and surgical critically ill patients, the authors concluded. “Further research should focus on retrospective external validation of the ICU-VTE score in other cohorts, prospective evaluation of score performance after integration into EMR systems, and exploration of how adjunctive testing for hypercoagulability (i.e., with viscoelastic testing) might further improve predictive accuracy,” they said.