A preliminary review of warfarin toxicity in a tertiary hospital in Cape Town, South Africa.

AIM Warfarin is a widely used anticoagulant for the prevention and treatment of thromboembolism. We conducted a retrospective review to determine the causes and management of warfarin toxicity of patients admitted to Tygerberg hospital between June 2014 and June 2015. RESULTS We identified and evaluated 126 patients who met the inclusion criteria. The cause of warfarin toxicity was identified and addressed in only 14.3% (18/126) of patients. Where the cause was identified, 56% (10/18) was due to dosing errors and 17% (3/18) drug-drug interaction (DDI). However, 77% (97/126) of patients were retrospectively identified as receiving concomitant medicines known to interact with warfarin at the time of admission. Twenty-eight percent (35/126) of patients presented with major bleeding, which included seven cases of intracranial haemorrhage. Patients were admitted for a median of eight days at an average treatment cost of R10 578. CONCLUSION We found that warfarin toxicity carries significant mortality and cost, but little attention is paid to the causes of toxicity.