Objective: To compare Anti-Xa directed thromboprophylaxis using low molecular weight heparin (LMWH) (anti-Xa peak goal 0.2-0.5 IU/mL) to alternative anticoagulation strategies in critically ill COVID-19 patients. Methods: This was a retrospective, multicenter, single health-system study. Primary outcomes were thromboembolic events and clinically important bleeding events. Secondary outcomes included dosing comparisons between LMWH cohorts. Main Results: A total of 695 patients were included. No differences were found in the incidence of thrombotic events with any of the dosing strategies. The incidence of major bleeding was significantly higher in the standard dose thromboprophylaxis, intermediate dose subcutaneous heparin (SQH), and therapeutic anticoagulation cohorts. Forty-nine percent of patients within the anti-Xa directed group had their first anti-Xa peak at goal, while 43% were above goal. Patients who had levels above goal had dose modifications made, therefore anti-Xa directed LMWH resulted in significantly lower total daily doses compared to intermediate dose LMWH. Conclusions: Anti-Xa directed LMWH dosing provided comparable thromboprophylaxis with lower total daily doses of LMWH in critically ill COVID-19 patients. Further randomized controlled trials are needed to confirm our findings.

目的：比较使用低分子量肝素 (LMWH) 的抗 Xa 定向血栓预防（抗 Xa 峰值目标 0.2-0.5 IU/mL）与危重 COVID-19 患者的替代抗凝策略。方法：这是一项回顾性、多中心、单一卫生系统研究。主要结局是血栓栓塞事件和临床上重要的出血事件。次要结果包括 LMWH 队列之间的剂量比较。主要结果：共纳入 695 名患者。任何给药策略的血栓事件发生率均未发现差异。在标准剂量血栓预防、中剂量皮下肝素 (SQH) 和治疗性抗凝组中，大出血的发生率显着更高。抗 Xa 定向组中 49% 的患者在达到目标时首次出现抗 Xa 峰，而 43% 的患者高于目标。水平高于目标的患者进行了剂量调整，因此与中间剂量 LMWH 相比，抗 Xa 定向 LMWH 导致每日总剂量显着降低。结论：在危重 COVID-19 患者中，抗 Xa 定向 LMWH 剂量提供了与较低的每日总剂量 LMWH 相当的血栓预防。需要进一步的随机对照试验来证实我们的发现。