Synopsis om studie

Synopsis om studie

Home-monitoring of INR and risk of death during warfarin treatment


We have earlier studied risk of death in relation to INR during warfarin treatment (1;2) and in addition demonstrated that the best predictor of death is use of the standard deviation of the transformed value of INR (SD-INR)(3). These mathematical findings from a large database in Sweden opens a unique opportunity to answer the question how monitoring of INR with a few days between measurements of INR can further reduce risk of death. Own simulation studies and experiences by Horstkotte(4) shows the SD can be greatly reduced but the question is to what extent we should individualize already from start of treatment and how much this will reduce the risk of death. From earlier studies we have developed an algorithm that will be used during the study but it has to be tested and modified from data obtained from short intervals. Such data can be obtained from patients staying in hospitals where daily or almost daily measurements and doses are recorded as a routine.


We want to assess that the standard deviation can be substantially reduced by frequent measurements of INR and adjustment of the dose in accordance with an algorithm. Therefore 20 patients will be randomized to frequent measurements with Coagucheck and 20 patients to traditional warfarin monitoring. The patients will be followed for 6 months and the two groups will be compared with respect to the standard deviations. In order to make the algorithm as good as possible we want to retrospectively investigate INR data from patients treated with warfarin in hospitals.

Reference List
  1. Oden A, Fahlen M. Oral anticoagulation and risk of death: a medical record linkage study. BMJ 2002 Nov 9;325(7372):1073-5.
  2. Oden A, Fahlen M, Hart RG. Optimal INR for prevention of stroke and death in atrial fibrillation: a critical appraisal. Thromb.Res. 2006;117(5):493-9.
  3. Lind M, Fahlen M, Kosiborod M, Eliasson B, Oden A. Variability of INR and its relationship with mortality, stroke, bleeding and hospitalisations in patients with atrial fibrillation. Thromb.Res. 2012 Jan;129(1):32-5.
  4. Horstkotte D, Piper C, Wiemer M. Optimal Frequency of Patient Monitoring and Intensity of Oral Anticoagulation Therapy in Valvular Heart Disease. J.Thromb.Thrombolysis. 1998 Jan;5 Suppl 1(3):19-24.