[Warfarin treatment in a general practice]

Warfarin treatment gives a well-documented reduction of the risk of thrombosis, but makes the patients more liable to bleedings. In Norway most patients are treated in general practice.

This study describes a 16-year-material (1988-2003) of 427 patients on warfarin in a practice with five general practitioners, based on retrospective analysis of patient files. A more detailed survey was done for the last four years (260 patients).

The prevalence of warfarin treatment in the practice increased from 0.9% to 2.7%, mostly because of increased treatment of atrial fibrillation. The average age of patients increased from 64 years to 72 years. 57% of the INR measurements were within therapeutic range. There were 16 haemorrhages pr 100 patient years with the majority occurring on therapeutic INR values. 14 serious haemorrhages were registered (2.4 pr 100 patient years), including seven cerebral haemorrhages resulting in three permanent cases of paralysis and one death. 14 patients had new disease diagnosed due to the bleeding. Only 1 patient experienced a venous thrombosis during 572 patient years of treatment. However, on 3 occasions thrombosis occurred shortly after termination of warfarin treatment.

Prevalence of warfarin treatment was higher than usual. The numbers of INR values within therapeutic range and numbers of serious bleedings were comparable to other studies. In spite of risk of haemorrhage, warfarin is a worthwhile treatment and can be carried out in general practice.