Timing of Hospital-acquired Venous Thromboembolism and Its Relationship with Venous Thromboembolism Prevention Measures in Immobile Patients

Background: The aim of this study is to describe the timing of venous thromboembolism (VTE) diagnosis in patients with cerebral or spinal trauma and stroke and describe the relationships between VTE prophylaxis and timing of VTE diagnosis at a community hospital. Methods: Retrospective cohort observational study over a span of 10 years from 2006 to 2016 was conducted. Results: Lower extremity ultrasound surveillance identified 138 patients who developed VTE during their hospital stay (mean age 62 years, 61.6% males). Mechanical prophylaxis was used in 79.7% and pharmacologic prophylaxis in 78.3% of patients. The average time of admission to administration of mechanical prophylaxis was 1.92 and 7.7 days for pharmacologic prophylaxis. In patients who received pharmacologic prophylaxis within 2 days, 51.5% of all VTE events occurred during the first week, 73.5% by the second week, and 91.2% by the third week of the hospital stay. In patients who started pharmacologic prophylaxis after 2 days in the hospital, 85% of all VTE events occurred within the first week and 90% within 10 days of the hospital stay (P < 0.001). The timing of initiation of mechanical prophylaxis did not influence the timing of VTE events. Conclusions: In immobilized patients with stroke, traumatic brain injury, or spinal cord injury, VTE screening should be performed at different schedules based on the timing of initiation of pharmacologic prophylaxis. In patients who did not start prophylaxis during the first 2 days of admission to the hospital, the majority of the VTE events occurred during the first 10 days.