Determining a preoperative international normalised ratio threshold safe for hip fracture surgery.

INTRODUCTION

The purpose of this study was first, to assess the relationship between preoperative INR (international normalised ratio) and postoperative complication rates in patients with a hip fracture, and second, to establish a threshold for INR below which the risk of complications is comparable to those in patients with a normal INR.

METHODS

We retrospectively reviewed the American College of Surgeons National Surgical Quality Improvement Program and found 35,910 cases who had undergone surgery for a hip fracture between 2012 and 2018. Cases were stratified into 4 groups based on their preoperative INR levels: <1.4; ⩾1.4 and <1.6; ⩾1.6 and <1.8 and ⩾1.8. These cohorts were assessed for differences in preoperative factors, intraoperative factors, and postoperative course. Multivariate logistic regression was used to assess the risk of transfusion, 30-day mortality, cardiac complications, and wound complications adjusting for all preoperative and intraoperative factors.

RESULTS

Of the 35,910 cases, 33,484 (93.2%) had a preoperative INR < 1.4; 867 (2.4%) an INR ⩾1.4 and <1.6; 865 (2.4%) an INR ⩾ 1.6 and <1.8 and 692 (1.9%) an INR ⩾ 1.8. A preoperative INR ⩾ 1.8 was independently associated with an increased risk of bleeding requiring transfusion. A preoperative INR ⩾ 1.6 was associated with an increased risk of mortality.

CONCLUSIONS

We found that an INR of <1.6 is a safe value for patients who are to undergo surgery for a hip fracture. Below this value, patients avoid an increased risk of both transfusion and 30-day mortality seen with higher INR values. These findings may allow adjustment of preoperative protocols and improve the outcome of hip fracture surgery in this group of patients.