Multisite validation of a venous thrombosis risk model in critically ill children through the CHAT Consortium

Abstract: Critically ill children are at a high risk for hospital-associated venous thromboembolism (HA-VTE). Developing a validated risk assessment model (RAM) to identify children who may benefit from thromboprophylaxis is essential. We aimed to prospectively validate the Children’s Healthcare Advancements in Thrombosis (CHAT)–intensive care unit (ICU) VTE RAM (CHAT-ICU RAM), containing 5 clinically significant variables: central venous catheter, immobility, congenital heart disease, autoimmune or inflammatory conditions, and hospital stay of ≥3 days in a multicenter cohort study. Randomly selected patients aged 0 to 21 years admitted to a pediatric ICU (PICU) at 32 institutions were monitored through medical record review for HA-VTE. Discrimination was assessed using the area under the receiver operating characteristic (AUROC) curve. Calibration was assessed using calibration plots. Complete-case and imputed analyses were performed, and model risk scores were generated along with posttest probability. The RAM was validated in 4674 patients, with an AUROC of 0.71, a calibration slope of 1.0, and an intercept of 1.81 × 10−5. The AUROC for the imputed model was 0.69 with a calibration slope of 1.03 and an intercept of 1.22 × 10−3. Calculated risk scores were 1 or 2 for each variable in the RAM with a total risk score ranging from 0 to 6. The estimated probability of developing HA-VTE ranged from 1% to 17.4% depending on the total score. In conclusion, the CHAT-ICU RAM has good discriminatory validity, is well calibrated, and reliably identifies children in the PICU at high and low risk of HA-VTE.