Association between Interruptions in Chemical Prophylaxis and VTE Formation

Venous thromboembolisms (VTE) are considered preventable events with appropriate mechanical or chemical prophylaxis. However, chemical prophylaxis is frequently delayed or interrupted during hospitalization. We investigated the impact of delayed initiation and interruption of chemical prophylaxis on VTE rates. The incidence of VTE at an urban academic medical center was measured in patients hospitalized for >2 days between November 2013 and May 2014. Patients receiving prophylaxis were grouped as complete (started within 24 hours of admission and no interruptions), delayed (started >24 hours and no interruptions), and interrupted (interruption for >24 hours with or without delay). There were 9961 hospital admissions and 33 VTE (3.3 per 1000 admissions). 25.2 per cent had complete, 16.4 per cent had delayed, and 11.8 per cent had interrupted prophylaxis. 36.8 per cent received no prophylaxis. Interrupted prophylaxis was associated with more VTE than complete (10.2 vs 2.0 per 1000, P < 0.01) and 5.2 greater odds. Admission to a surgical service and prolonged hospital stay were independently associated with increased likelihood of VTE. There was a lower likelihood of getting complete prophylaxis among patients admitted to orthopedic, transplant, cardiac, plastic, and vascular surgery. Surgical patients are at higher risk for VTE and interruptions in VTE prophylaxis significantly increase the risk of VTE.