A model for perioperative outpatient management of anticoagulation in high-risk patients: An evaluation of effectiveness and safety

Objective: To assess the effectiveness and safety of a hospital-based perioperative outpatient program for patients at risk for thromboembolic complications who require temporary interruption of oral anticoagulants for dental, surgical, or diagnostic procedures. Methods: A prospective cohort study was performed with consecutive high-risk patients receiving long-term oral anticoagulant therapy who required surgical procedures during a 12-month study period. High-risk patients were defined as those with recent or recurrent venous thromboembolism, atrial fibrillation and a major risk factor, one or more mechanical heart valves, or congestive heart failure with left ventricular ejection fraction less than 30%. Warfarin was discontinued 5 days before the procedure, and 1 of 3 dalteparin regimens was started: 5000 units SC od, 200 units/kg SC od, or 120 units/kg SC bid. Dalteparin therapy was continued until 24 h before the surgery and then restarted 12 h after the procedure, along with warfarin. Dalteparin was continued until the international normalized ratio was within the therapeutic range. Rates of thromboembolic and hemorrhagic complications were recorded, and the number of hospital days avoided was estimated. Results: The 47 participants underwent the following procedures: removal of colonic polyp (9 patients); cardiac catheterization (8); orthopedic surgery (7); colonoscopy, endoscopy, or bronchoscopy (7); dental surgery (6); ocular surgery (2); surgical biopsy (2); and nephrectomy, splenectomy, prostatectomy, oopherectomy, vasectomy, and endarterectomy (1 each). Two patients (4%, 95% confidence interval [CI] 1% to 14%) experienced a thromboemoblic event, 2 patients (4%, 95% CI 1% to 14%) had minor hemorrhage, and no patients had major hemorrhage in the perioperative period. Conclusion: Patients undergoing long-term anticoagulation who are at high risk for thromboembolic complications can be safely and effectively treated with low-molecular-weight heparin on an outpatient basis according to a hospital-based perioperative treatment model of care.