The use of warfarin in Christchurch for the treatment of venous thromboembolism.

AIMS

To identify the actual duration of warfarin therapy received by patients being treated for venous thromboembolism (VTE) compared to that initially intended. To determine the incidence of major haemorrhage during therapy.

METHODS

The subjects were 505 consecutive medical inpatients who were referred for a lung scan because of suspected pulmonary embolism. Three years following the discharge of the last patient, hospital notes, local and national computer databases were searched for subsequent relevant events. Surviving subjects were also contacted by telephone or letter.

RESULTS

115/505 (23%) received warfarin therapy for VTE. Direct personal contact was made with 314/352 (89%) surviving patients, including 79/82 (98%) surviving patients who were on warfarin. The intended duration of therapy was specified initially in 60/115 treated cases (52%), and these patients were less likely to be still receiving warfarin 3-4 years later (p<0.001). Indefinite therapy was initially recommended in 11/115 cases (10%), but 26/79 surviving subjects (32%) were known to be still receiving warfarin 3-4 years later. Seven treated subjects had a diagnosed recurrence of VTE. There were no clear indications for prolonged therapy in the remainder. Major haemorrhage occurred eighteen times among 115 treated patients (16%), and in two of these warfarin associated bleeding was considered to be the cause of death. None of these events was reported to the Centre for Adverse Reactions Monitoring.

CONCLUSIONS

The intended duration of therapy was often unclear and warfarin was generally continued for much longer than is currently considered necessary. Haemorrhagic events were relatively common and were not reported.