Evaluation of International Normalized Ratio Thresholds for Complications in Hip Fractures Treated With Intramedullary Nailing: Analysis of 15,323 Cases

INTRODUCTION: In hip fracture patients with elevated international normalized ratios (INRs), the risks of delaying surgery for correction of INR are controversial. We examined the association of (1) preoperative INR values and (2) surgical delay with postoperative complications after intramedullary nailing of hip fractures. METHODS: Using the National Surgical Quality Improvement Program database, we retrospectively identified patients that underwent intramedullary nailing for hip fractures from 2005 to 2016. Patients aged older than 55 years with preoperative INR recorded ≤1 day before surgery were included. Patients were stratified into five cohorts-(1) INR ≤ 1.0, (2) 1 < INR ≤ 1.25 (INR [1 to 1.25]), (3) 1.25 < INR ≤ 1.5 (INR [1.25 to 1.5]), (4) 1.5 < INR ≤ 2.0 (INR [1.5 to 2.0]), and (5) INR > 2.0. The primary outcomes of interest were postoperative bleeding requiring transfusion, surgical site infection, and 30-day mortality. Multivariate regression analysis was done to adjust for potential confounding variables. RESULTS: In total, 15,323 patients were included in this analysis. Adjusting for potential confounders, INR [1 to 1.25], INR [1.25 to 1.5], and INR [1.5 to 2.0] were associated with increased mortality (adjusted odds ratio [aOR]: 1.501, P < 0.001; aOR: 2.226, P < 0.001; aOR: 2.524, P < 0.001, respectively) and surgical delay >48 hours (aOR: 1.655, P < 0.001; aOR: 3.434, P < 0.001; aOR: 2.382, P < 0.001, respectively). The INR > 2.0 cohort was not associated with mortality (P = 0.181) or surgical delay (P = 0.529). Surgical delay was associated with mortality (aOR: 1.531, P = 0.004). The INR > 2.0 cohort was associated with increased rate of transfusions (aOR: 1.388, P = 0.039). CONCLUSION: Elevated preoperative INR value within 1 day of surgery between 1.0 and 2.0 was associated with increased risk of 30-day mortality and surgical delay >48 hour, which may represent attempts at INR correction. An INR greater than 2.0 was not associated with mortality or surgical delay but was associated with increased transfusions. Surgical delay was independently associated with increased risk of 30-day mortality. We therefore recommend that INR reversal be attempted but not delay surgical fixation of geriatric hip fractures over 48 hours and counsel patients and their families regarding the risks of surgery with elevated INR. LEVEL OF EVIDENCE: Prognostic-level III/retrospective cohort study.