The relationship of pre-operative laboratory coagulation parameters with post-operative hemorrhage in neurosurgical patients

Abstract

Background: Neurosurgeons are frequently asked to operate on patients with blood clotting abnormalities. During the last twenty years, the use of NSAIDs has skyrocketed. Patients taking ASA and NSAIDs are routinely asked to stop these medications before an elective operation. INR is a widely used measure of the extrinsic pathway of coagulation. The INR value at which neurosurgeons are willing to proceed with elective surgical procedures is not grounded in strong evidence. The principal objective of this study is to determine the relationship between preoperative coagulation status (as measured by objective laboratory tests) and the rate of clinically significant central nervous system hemorrhage after neurosurgical procedures Methods: This is a retrospective case-control study of operative neurosurgical patients from the University of Minnesota Medical Center from 2003 to 2009. Within this group of 3698 operative cases there were 43 cases of post-operative hemorrhage. Results: The overall rate of hemorrhage during this period was 1.2%. After adjusting for procedure class, the odds having a hemorrhage increased by 73.4% as INR increased by 0.1 unit (p=0.0062) The total N for the final model was 174, representing exclusion of 28 patients who did not have complete records Discussion: Patients suffering a hemorrhage within 30 days of operation were more likely to have had an elevated INR than control patients. While values such as INR are used to assess the coagulation cascade, we have seen that many other factors are purported to contribute to post-operative hemorrhage. These potential confounding factors were collected and evaluated in this study. The results of our series support the idea that, by further refining the ability to predict risk of postoperative hemorrhage, a prospectively collected cohort of neurosurgical patients and their risk factors for post-operative hemorrhage could make a significant contribution to the safe practice of neurosurgery.