Chadi Tannoury, Ryan Sutton.

Response/Recommendation: Warfarin (Coumadin) should be discontinued at least 5 days before spine surgery, and the international normalized ratio (INR) goal should be 1.2 or less.

Strength of the Recommendation: Moderate.

Rationale: Warfarin, a vitamin K antagonist (36 – 42 hours half-life), reduces the function of clotting factors II, VII, IX, and X by blocking the vitamin K epoxide reductase enzyme¹. It is a commonly used anticoagulant for treatment of deep venous thrombosis (DVT) and pulmonary embolism (PE), and prevention of cerebrovascular accidents in patients with atrial fibrillation, valvular heart disease, or artificial heart valves. Perioperative continuation of warfarin can be associated with increased risk of bleeding². Rokito et al., reported that in patients undergoing major reconstructive spinal surgery, the perioperative use of warfarin can be associated with major blood loss (> 800 mL) while adding no benefit in DVT prevention compared to the use of compression stocking and sequential compression devices³. Benzon et al., studied the remaining anticoagulation effect of warfarin five days after its discontinuation. In the majority of patients (n = 21), the INR normalized to less than 1.2, which was considered adequate for safe neuraxial procedures⁴. A small number of patients (n = 2) had INR values of 1.3 or 1.4. However, the safety of this INR range for neuraxial injections was considered inconclusive⁴. Narouze et al., and the American Society of Regional Anesthesia (ASRA) published guidelines recommending stopping warfarin five to six days before interventional spine and pain procedures, with a goal INR of 1.4 or less⁵. While most available data suggest withholding warfarin for a minimum of five preoperative days to be reasonably safe in patients undergoing spinal surgeries, there is concern for increased operative blood loss even after seven days of warfarin discontinuation. Young et al., evaluated 263 patients undergoing elective lumbar spine surgery including laminectomy with and without instrumented posterolateral fusion⁶. All patients on warfarin had their anticoagulation stopped seven days prior to surgery⁶. They noted that patients on warfarin (n = 13) had significant increase in intraoperative blood loss (839 mL vs. 441 mL) and postoperative blood transfusions (23% vs. 7.4%, p = 0.04) compared to patients not on warfarin (n = 250)⁶. Despite the limited data on neurologic and spinal surgery, warfarin discontinuation is recommended for a minimum of five preoperative days. Additionally, while a goal INR of 1.4 or less is acceptable, a more conservative range of 1.2 or less is adequate for safe spinal surgeries.

References:

1. Ageno W, Gallus AS, Wittkowsky A, Crowther M, Hylek EM, Palareti G. Oral anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012 Feb;141(2 Suppl): e44S-e88S.
2. Coumadin. Princeton, NJ: Bristol-Myers Squibb Company; 1954.
3. Rokito SE, Schwartz MC, Neuwirth MG. Deep vein thrombosis after major reconstructive spinal surgery. Spine. Apr 1 1996; 21(7): 853-8; discussion 859.
4. Benzon HT, Asher Y, Kendall MC, Vida L, McCarthy RJ, Green D. Clotting-factor concentrations 5 days after discontinuation of warfarin. Reg Anesth Pain Med. 2018; 43: 616-620.
5. Narouze S, Benzon HT, Provenzano D, Buvanendran A, De Andres J, Deer T, Rauck R, Huntoon MA. Interventional Spine and Pain Procedures in Patients on Antiplatelet and Anticoagulant Medications (Second Edition): Guidelines From the American Society of Regional Anesthesia and Pain Medicine, the European Society of Regional Anaesthesia and Pain Therapy, the American Academy of Pain Medicine, the International Neuromodulation Society, the North American Neuromodulation Society, and the World Institute of Pain. Reg Anesth Pain Med. 2018 Apr; 43(3): 225-262.
6. Young EY, Ahmadinia K, Bajwa N, Ahn NU. Does chronic warfarin cause increased blood loss and transfusion during lumbar spinal surgery? Spine J. 2013; 13: 1253-58.