title: A 10 mg warfarin initiation nomogram is safe and effective in outpatients starting oral anticoagulant therapy for venous thromboembolism.
abstract: The optimal means of initiating warfarin therapy for acute venous thromboembolism in the outpatient setting remains controversial. We have previously demonstrated the efficacy of a 10 mg initiation nomogram in a randomized controlled trial; however, some clinicians remain reluctant to use this nomogram due to a fear of potential increased bleeding. To review the safety and efficacy of a 10 mg warfarin nomogram we conducted a retrospective cohort study of patients prospectively treated for venous thromboembolism according to a 10 mg nomogram in an outpatient thrombosis clinic. All patients received standard treatment with low molecular weight heparin for 5 to 7 days and warfarin for at least 3 months. Four-hundred and fourteen patients were included in the analysis, of whom 295 (71%) fully adhered to the nomogram. In the whole cohort, 8 patients (1.9%) experienced recurrent thrombosis, 4 (0.97%) suffered a major bleeding event, and 3 (0.72%) suffered a minor bleeding event. There were no deaths related to thrombosis or bleeding. Four patients (0.97%) died from unrelated causes. Twenty-two (5.3%) patients experienced an INR > or =5.0 in the first 8 days of therapy, and none of these patients experienced a bleeding event. Eighty-four percent of patients achieved a therapeutic INR by day 5. In outpatients, a 10 mg nomogram results in timely achievement of a therapeutic INR with an acceptable incidence of bleeding and recurrent thromboembolism.
authors.affiliation: Department of Medicine, Division of Hematology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Katherine
authors.initials: K
authors.lastname: Monkman
authors.forename: Alejandro
authors.initials: A
authors.lastname: Lazo-Langner
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kovacs
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000379:methods*; D000925:Anticoagulants / Q000008:administration & dosage*; D015897:Comorbidity; D004305:Dose-Response Relationship, Drug; D005260:Female; D006470:Hemorrhage / Q000401:mortality*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000188:drug therapy* / Q000401:mortality*; D014859:Warfarin / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D000925:Anticoagulants; D014859:Warfarin