title: The risk of overanticoagulation in patients with heart failure on coumarin anticoagulants.
abstract: Heart failure has been identified as a risk factor for increased coumarin anticoagulant responsiveness in several small-scale experiments. Epidemiological studies quantifying the risk of overanticoagulation by heart failure in a non-selected population on coumarins are scarce. Therefore, we investigated whether patients with heart failure have an increased risk of overanticoagulation and determined the effect of incidental heart failure on coumarin dose requirements. A cohort study of all patients was performed from an outpatient anticoagulation clinic treated with acenocoumarol or phenprocoumon between 1 January 1990 and 1 January 2000. All cohort members were followed until the first occurrence of an international normalized ratio (INR) > or = 6.0, the last INR assessment, death, loss to follow-up, or end of the study period. Of the 1077 patients in the cohort, 396 developed an INR > or = 6.0. The risk of overanticoagulation was 1.66 [95% confidence interval (CI): 1.33-2.07] for cases of prevalent heart failure and 1.91 (95%CI: 1.31-2.79) for incidental cases. The decrease in dose requirements in patients with incidental heart failure showed a significant trend from the fifth INR measurement preceding the date of incidental heart failure to the third measurement after this date. Heart failure is an independent risk factor for overanticoagulation. Therefore, patients with heart failure should be closely monitored to prevent potential bleeding complications.
authors.affiliation: Pharmacoepidemiology Unit, Department of Internal Medicine and Epidemiology and Biostatistics, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: Loes E
authors.initials: LE
authors.lastname: Visser
authors.forename: Gysèle S
authors.initials: GS
authors.lastname: Bleumink
authors.forename: Paul H
authors.initials: PH
authors.lastname: Trienekens
authors.forename: Arnold G
authors.initials: AG
authors.lastname: Vulto
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Bruno H Ch
authors.initials: BH
authors.lastname: Stricker
mesh_terms: D000074:Acenocoumarol / Q000008:administration & dosage* / Q000494:pharmacology; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects; D004334:Drug Administration Schedule; D016903:Drug Monitoring; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood*; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D010644:Phenprocoumon / Q000008:administration & dosage* / Q000494:pharmacology; D012307:Risk Factors
chemical_list: D000925:Anticoagulants; D000074:Acenocoumarol; D010644:Phenprocoumon