Korrelation der anti-Xa-Spiegel mit den anti-IIa-Spiegeln und der Thrombingenerierung bei Patienten mit Adipositas unter Thrombose-Prophylaxe

Abstract

Background: The optimal dose of tinzaparin for prophylaxis in obese medical patients is not well defined. Objectives: To evaluate the anti-Xa activity in obese medical patients on tinzaparin prophylaxis adjusted for actual bodyweight. Methods: Patients with a body mass index of ≥30 kg/m2 treated with 50 IU/kg tin- zaparin once daily were prospectively included. Anti-Xa and anti-IIa activity; von Wil- lebrand factor antigen and von Willebrand activity; factor VIII activity; D-dimer, prothrombin fragments; and thrombin generation were measured 4 hours after sub- cutaneous injection between days 1 and 14 after the initiation of tinzaparin prophylaxis. Results: We included 121 plasma samples from 66 patients (48.5% women), with a median weight of 125 kg (range, 82-300 kg) and a median body mass index of 41.9 kg/ m2 (range, 30.1-88.6 kg/m2). The target anti-Xa activity of 0.2 to 0.4 IU/mL was ach- ieved in 80 plasma samples (66.1%); 39 samples (32.2%) were below and 2 samples (1.7%) above the target range. The median anti-Xa activity was 0.25 IU/mL (IQR, 0.19- 0.31 IU/mL), 0.23 IU/mL (IQR, 0.17-0.28 IU/mL), and 0.21 IU/mL (IQR, 0.17-0.25 IU/mL) on days 1 to 3, days 4 to 6, and days 7 to 14, respectively. The anti-Xa activity did not differ among the weight groups (P = .19). Injection into the upper arm compared to the abdomen resulted in a lower endogenous thrombin potential, a lower peak thrombin, and a trend to a higher anti-Xa activity. Conclusion: Dosing of tinzaparin adjusted for actual bodyweight in obese patients achieved anti-Xa activity in the target range for most patients, without accumulation or overdosing. In addition, there is a significant difference in thrombin generation depending on the injection site