Protocol for the Catheter-Related Early Thromboprophylaxis With Enoxaparin (CRETE) Studies.

Abstract

Objectives: In post hoc analyses of our previous phase 2b Bayesian randomized clinical trial (RCT), prophylaxis with enoxaparin reduced central venous catheter (CVC)-associated deep venous thrombosis (CADVT) in critically ill older children but not in infants. The goal of the Catheter-Related Early Thromboprophylaxis with Enoxaparin (CRETE) Studies is to investigate this newly identified age-dependent heterogeneity in the efficacy of prophylaxis with enoxaparin against CADVT in critically ill children.

Design: Two parallel, multicenter Bayesian superiority explanatory RCTs, that is, phase 3 for older children and phase 2b for infants, and an exploratory mechanistic nested case-control study (Trial Registration ClinicalTrials.gov NCT04924322, June 7, 2021).

Setting: At least 15 PICUs across the United States.

Patients: Older children 1-17 years old ( n = 90) and infants older than 36 weeks corrected gestational age younger than 1 year old ( n = 168) admitted to the PICU with an untunneled CVC inserted in the prior 24 hours. Subjects with or at high risk of clinically relevant bleeding will be excluded.

Interventions: Prophylactic dose of enoxaparin starting at 0.5 mg/kg then adjusted to anti-Xa range of 0.2-0.5 international units (IU)/mL for older children and therapeutic dose of enoxaparin starting at 1.5 mg/kg then adjusted to anti-Xa range of greater than 0.5-1.0 IU/mL or 0.2-0.5 IU/mL for infants while CVC is in situ.

Measurements and main results: Randomization is 2:1 to enoxaparin or usual care (no enoxaparin) for older children and 1:1:1 to either of 2 anti-Xa ranges of enoxaparin or usual care for infants. Ultrasonography will be performed after removal of CVC to assess for CADVT. Subjects will be monitored for bleeding. Platelet poor plasma will be analyzed for markers of thrombin generation. Samples from subjects with CADVT will be counter-matched 1:1 to subjects without CADVT from the opposite trial arm. Institutional Review Board approved the "CRETE Studies" on July 1, 2021. Enrollment is ongoing with planned completion in July 2025 for older children and July 2026 for infants.