Monitoring Direct Thrombin Inhibitors With Calibrated Diluted Thrombin Time vs Activated Partial Thromboplastin Time...

Area of Science:

• Pharmacology
• Clinical Chemistry
• Pediatric Medicine

Background:

• Activated partial thromboplastin time (aPTT) is the standard monitoring test for intravenous direct thrombin inhibitors (DTIs), but it has significant limitations.
• The plasma diluted thrombin time (dTT) assay has emerged as a potentially more reliable alternative for assessing DTI levels.

Purpose of the Study:

• To compare the dose-response relationship of dTT and aPTT in pediatric patients receiving argatroban or bivalirudin.
• To evaluate the analytic performance and clinical utility of dTT for monitoring DTIs in a pediatric population.

Main Methods:

• A retrospective review was conducted on pediatric patients treated with argatroban (n=45) or bivalirudin (n=14).
• Both dTT and aPTT assays were used to monitor patients, and their dose-response curves were analyzed.

Main Results:

• The dTT assay demonstrated a fivefold higher likelihood of showing a stable dose-response slope compared to aPTT (P < .0002).
• When both assays correlated with drug dose, dTT showed a higher average correlation factor (P = .007).
• Argatroban exhibited greater inter- and intrapatient variability in dose-response slopes (132% CV) than bivalirudin (52% CV).

Conclusions:

• The dTT assay is more effective than aPTT in establishing a stable dose response and correlating with direct thrombin inhibitor levels.
• Argatroban monitoring shows higher variability in dose response compared to bivalirudin, highlighting the need for precise monitoring methods.