title: Initiation of warfarin therapy in elderly medical inpatients: a safe and accurate regimen.
abstract: OBJECTIVE
  Elderly patients are at high risk of over-anticoagulation when treated with warfarin, especially during treatment induction. We developed a simple low-dose regimen for starting warfarin therapy in elderly inpatients. The daily maintenance dosage is predicted from the international normalized ratio (INR) measured the day after the third daily intake of a 4-mg dose. We conducted a prospective multicenter study to evaluate the accuracy and safety of this regimen.
  
  
  METHODS
  We studied 106 elderly (age >or=70 years) inpatients (mean [+/- SD] age, 85 +/- 6 years; range, 71 to 97 years) who had a target INR of 2.0 to 3.0. Accuracy in predicting the daily maintenance dose from INR value on day 3 was evaluated.
  
  
  RESULTS
  The predicted daily maintenance warfarin dose (3.1 +/- 1.6 mg/d) correlated closely with the actual maintenance dose (3.2 +/- 1.7 mg/d; R(2) = 0.84). The predicted dose was equal to the actual dose in 77 patients (73%; 95% confidence interval [CI]: 64% to 81%) and within 1 mg in 101 patients (95%; 95% CI: 91% to 99%). The mean time needed to achieve a therapeutic INR was 6.7 +/- 3.3 days (median, 6.0 days); the mean time needed to achieve the maintenance dose was 9.2 +/- 4.5 days (median, 7.0 days). None of the patients had an INR >4.0 during this period. One fatal bleeding event was recorded in a patient with an INR in the therapeutic range.
  
  
  CONCLUSIONS
  Our warfarin induction regimen was simple, safe, and accurate in predicting the daily maintenance warfarin dose in elderly hospitalized patients.
authors.affiliation: Hematology Laboratory, Charles Foix Teaching Hospital (AP-HP), Paris, France. virginie.siguret@cfx.ap-hop-paris.fr
authors.forename: Virginie
authors.initials: V
authors.lastname: Siguret
authors.forename: Isabelle
authors.initials: I
authors.lastname: Gouin
authors.forename: Matthieu
authors.initials: M
authors.lastname: Debray
authors.forename: Christine
authors.initials: C
authors.lastname: Perret-Guillaume
authors.forename: Jacques
authors.initials: J
authors.lastname: Boddaert
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mahé
authors.forename: Valérie
authors.initials: V
authors.lastname: Donval
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Seux
authors.forename: Marjolaine
authors.initials: M
authors.lastname: Romain-Pilotaz
authors.forename: Mathilde
authors.initials: M
authors.lastname: Gisselbrecht
authors.forename: Marc
authors.initials: M
authors.lastname: Verny
authors.forename: Eric
authors.initials: E
authors.lastname: Pautas
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects* / Q000493:pharmacokinetics / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005544:Forecasting; D006801:Humans; D007297:Inpatients; D008297:Male; D010347:Patient Care Planning; D013927:Thrombosis / Q000517:prevention & control*; D014859:Warfarin / Q000008:administration & dosage* / Q000009:adverse effects* / Q000493:pharmacokinetics / Q000627:therapeutic use
chemical_list: D000925:Anticoagulants; D014859:Warfarin