Practice Patterns of Venous Thromboembolism Prophylaxis in Underweight, Critically Ill Patients with Neurologic Injury

Purpose Venous thromboembolism (VTE) prophylaxis in underweight patients with neurologic injury remains unaddressed by guidelines and primary literature. This study aimed to describe VTE prophylaxis strategies employed in this population and compare the impact of underweight and non-obese patients on thrombotic and bleeding events. Methods A retrospective review of adults admitted with a diagnosis of neurologic injury to a neurology/neurosurgery intensive care unit (ICU) over 6 years. Patients admitted >= 72 h with an order for VTE prophylaxis during admission, and a body mass index (BMI) < 30 kg/m(2) were included. Patients were stratified to underweight (BMI <= 18.5 kg/m(2) or weight <= 50.0 kg) or non-obese (BMI 18.6-29.9 kg/m(2)) groups and matched, 2:1, on age, diagnosis, and disease severity. Results The most common regimen in the underweight (n = 107) and non-obese (n = 214) group was unfractionated heparin (UFH) 5000 units subcutaneously Q12 h (69.1 vs. 83.6%; p = 0.003). Only underweight patients received UFH 2500 units subcutaneously Q12 h (17.8 vs. 0.0%; p < 0.0001). The proportion of overall bleeding and thrombotic events while receiving VTE prophylaxis was not significantly different. The proportion of underweight patients developing intracranial hematoma expansion while receiving prophylaxis versus non-obese patients (45.5 vs. 8.3%; p = 0.017) was significant. Patients receiving > 150 units/kg/day of UFH displayed a trend toward increased risk of bleeding (9.7 vs. 4.2%; p = 0.064). Conclusions Current practice does not reflect dose reductions for neurologically injured, underweight patients. Caution should be considered when using increased doses of UFH in neurologically injured patients that are underweight and/or may be exposed to > 150 units/kg/day of UFH. Continued assessment of VTE prophylaxis is needed to confirm these findings.