An ambulatory 70-year-old man, F.H., has been admitted to your hospital with a hip fracture that will require surgery. Although F.H. has a history of atrial fibrillation (AF) episodes and transient ischemic attacks (TIA), his heart is currently in normal sinus rhythm. Medications on admission included verapamil 120 mg and warfarin 5 mg daily; fracture pain is being treated with morphine intramuscular (IM) injections at present. F.H.'s INR (International Normalized Ratio) on admission is 2.8; blood pressure is 135/75; lab tests were within normal limits. F.H.'s physician requests an anticoagulation consult to aid him in determining the timing of surgery and venothromboembolism (VTE) prophylaxis. What do you suggest?

Hip fracture requiring surgical reduction is not an emergent procedure. The warfarin should be held until INR is near normal (≤1.5) before proceeding. Although limited background is known about this patient, history of AF without a stroke is classified as low risk for thromboembolism per the CHEST supplement. Recommendations suggest that bridging with subcutaneous unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) at a prophylactic dose would be sufficient while the patient's INR is subtherapeutic. At present there is no indication that a quicker reversal of the INR with vitamin K is needed. Postoperatively, warfarin should be reinitiated at the 5 mg daily (as before admission) starting the evening of surgery. Continue to bridge with heparin or LMWH at prophylactic doses until the INR is therapeutic.

Additionally, IM injections are not recommended in anticoagulated patients due to bleeding risk. An intravenous (IV) site should be established to deliver morphine if pain is not controlled with oral medication.

Michelle Lilliston, Pharm.D., BCPS
Clinical Pharmacist
Moses H. Cone Memorial Hospital
Greensboro, N.C.

Ideally the surgeon will want INR <1.5 prior to surgery (considering bleeding and anesthesia options) and will want that within one to two days. I would recommend holding warfarin until after surgery and giving oral vitamin K 2.5 mg with the expectation that INR will correct within 24 hours, or if surgery will take place sooner, give fresh frozen plasma to reverse INR. The risk of VTE is high after hip fracture surgery, as is the risk of further arterial events, given AF and TIA history. Reinitiation of full anticoagulation postsurgery would be preferred.

For ease of dosing and administration, I would use full treatment doses of enoxaparin 1 mg/kg every 12 hours (or if necessary, for CrCl <30 ml/min 1 mg/ kg/day) until the INR is therapeutic. This should be initiated six to 12 hours postsurgery as long as hemostasis has been achieved. I'd choose enoxaparin over IV UFH. With regard to warfarin, because we know the currently stable regimen, we could restart 5 mg at bedtime the night of surgery or the next day, or consider giving 7.5 mg for two days, then continue with 5 mg at bedtime to help achieve therapeutic INR quicker and minimize the number of days giving LMWH.

Nancy L. Shapiro, Pharm.D., BCPS
Clinical Pharmacist, Ambulatory Care
Clinical Assistant Professor, Dept. of Pharmacy Practice, University of Illinois at Chicago