Low Early Antifactor Xa Target Achievement Rate of Low-Molecular-Weight Heparin for Treating Venous Thromboembolism in Patients in Intensive Care.

This study aimed to evaluate whether early antifactor Xa (anti-Xa) achieved the target range when venous thromboembolism (VTE) was treated with low-molecular-weight heparin (LMWH), based on body weight and renal function in patients treated in intensive care units (ICUs). Anti-Xa levels in patients treated with LMWH for VTE in ICU and medical wards between January 1, 2021, and June 30, 2022, were retrospectively assessed. The demographics, laboratory parameters, and early anti-Xa peak levels of patients were collected. All patients were followed up for 3 months to collect VTE recurrence/bleeding events. Univariate and multivariate linear regression analyses were used to identify the factors affecting anti-Xa levels. A total of 108 patients were enrolled in this study, including 70 patients in ICU and 38 patients on medical wards. The early anti-Xa level (0.36 vs 0.61 IU/mL, P < .001) and target achievement rate (21.4% vs 39.5%, P = .015) of patients in ICU were lower than those in medical wards. Multivariate linear regression showed that only antithrombin (AT) significantly affected anti-Xa levels in patients in ICU (β = 0.008, 95%CI 0.005 to 0.011, P < .001). There was no significant difference in VTE recurrence events (11.8% vs 7.5%, P = .628) and bleeding events (29.4% vs 17.0%, P = .304) between the early anti-Xa within-target group and the early anti-Xa below-target group. Low anti-Xa peak levels are common in patients in ICU. AT activity should be monitored when using LMWH in critically ill patients.