Abstract
INTRODUCTION: Current guidelines recommend that the International Normalized Ratio (INR) be less than 1.5 prior to spine intervention. Recent studies have shown that an INR > 1.25 is associated worse outcomes following anterior cervical surgery. We sought to determine the risk of complications associated with an INR > 1.25 following elective posterior cervical surgery. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was queried. Patients undergoing elective posterior cervical surgery from 2012 to 2016 with an INR level within 24 h of surgery were included. Primary outcomes were hematoma requiring surgery, 30-day mortality, and transfusions within 72-hours. There were 815 patients in the INR ≤ 1 cohort (Cohort A), 410 patients in the 1 < INR ≤ 1.25 cohort (Cohort B), and 33 patients in the 1.25 < INR ≤ 1.5 cohort (Cohort C). RESULTS: Cohort C had a higher rate of transfusion (4% Cohort A; 6% Cohort B; 12% Cohort C; p = 0.028) and the rate of mortality within 30 days postoperatively trended toward significance (0.4% Cohort A; 0.5% Cohort B; 3% Cohort C; p = 0.094). There was no significant difference in the rate of postoperative hematoma formation requiring surgery (0.2% Cohort A; 0% Cohort B; 0% Cohort C; p = 0.58). On multivariate analysis, increasing INR was not associated with an increased risk of developing a major complication. CONCLUSION: An INR > 1.25 but ≤ 1.5 may be safe for posterior cervical surgery. An INR > 1.25 but ≤ 1.5 was associated with a significantly higher rate of transfusions. However, increasing INR was not significantly associated with increased risk of any of the major complications.