Date of Award

January 2018

Document Type


Degree Name

Medical Doctor (MD)



First Advisor

Jonathan Grauer


The current study aimed to characterize the incidence and risk factors for venous thromboembolism (VTE) and the association of pharmacologic prophylaxis with VTE and bleeding complications after elective spine surgery. A retrospective study was performed using the prospectively collected National Surgical Quality Improvement Program (NSQIP) database from 2005 to 2014 and at an academic medical center from 2013 to 2016. In the single institution cohort, a chart review was completed to determine use of VTE prophylaxis, history of prior VTE, and incidence of hematoma requiring reoperation. The associations of patient and procedure variables, including prophylaxis and history of prior VTE, with VTE and hematoma requiring reoperation were determined using multivariate regression. Independent risk factors for VTE included increasing body mass index, dependent functional status, lumbar surgery, longer operative time, perioperative blood transfusion, longer length of stay, and other postoperative complications. Pharmacologic prophylaxis with unfractionated heparin did not significantly influence the VTE rate but was associated with significant increase in hematoma requiring return to operating room (RR = 7.37; P = 0.048). This raises questions about routine use of unfractionated heparin for VTE prophylaxis and supports the need for further consideration of risks and benefits after elective spine surgery.


This thesis is restricted to Yale network users only. It will be made publicly available on 06/25/2100