Here is the abstract of a pre-publication release comparing direct thrombin inhibitor results from the plasma-diluted thrombin time [DTT] to the partial thromboplastin time [PTT]:
Hasan RA, Pak J, Kirk CJ, et al. Monitoring direct thrombin inhibitors with calibrated diluted thrombin time vs activated partial thromboplastin time in pediatric patients. Am J Clin Pathol 2022; HTTPS://DOI.ORG/10.1093/AJCP/AQAC131
Objectives: Activated partial thromboplastin time (aPTT) is the primary test used to monitor intravenous (IV) direct thrombin inhibitors (DTIs) but has many limitations. The plasma diluted thrombin time (dTT) has shown a better correlation with DTI levels than aPTT. This study compared dose-response curves for dTT and aPTT in pediatric patients receiving argatroban and bivalirudin.
Methods: A retrospective review of pediatric patients treated with argatroban (n = 45) or bivalirudin (n = 14) monitored with dTT and aPTT.
Results: The dTT assay was calibrated to report DTI concentrations in μg/mL for argatroban and bivalirudin with good analytic sensitivity and specificity. The dTT was fivefold more likely to show a stable dose-response slope than the aPTT (P < .0002; odds ratio, 4.9). For patients in whom both dTT and aPTT showed a significant correlation between dose and assay results, dTT had a higher average correlation factor compared with aPTT (P = .007). Argatroban dose-response slopes showed more inter- and intrapatient variation than bivalirudin (dose-response slope coefficient of variation, 132% vs 52%).
Conclusions: The dTT assay was more likely to show a stable dose-response and have a stronger correlation with DTI dose than aPTT. Argatroban shows more variation in dose-response than bivalirudin.