Direct and indirect costs of management of long-term warfarin therapy in Canada

Background: Comparisons of overall costs and resource utilization associated with anticoagulation management are important as new alternatives to warfarin are introduced. The aim of the present study was to assess total costs of warfarin-based anticoagulation in different health care models. Methods: Physician- or pharmacist-managed hospital- or community-based anticoagulation clinics in five Canadian provinces were asked to provide itemized information on costs for staff, laboratory, hardware and overheads associated with warfarin management. At each site, cohorts of patients were provided with diaries and participants prospectively entered all costs for warfarin medication and associated health professional contacts, travel to the laboratory, required assistance and time lost from work by patient or caregiver over 3 months. All costs were calculated for a 3-month period. Results: Data from 429 patients at 15 sites were evaluated. The cost from the Ministry of Health perspective ranged from $108 to $199 per 3 months in the different settings, the patient costs were $40-$80 and the total societal costs ranged from $188-$244. Sensitivity analyses with typical blood test intervals, the most prescribed strength of warfarin and dispensing fee from another province increased these estimates to $230-$302. When reimbursement for unemployed caregivers was also entered the total cost was $308-$503 per 3 months. Conclusions: The total cost for warfarin-based anticoagulation amounted to at least 10 times the lowest cost for the drug. The costs provided should be useful for comparisons with newer drugs without requirement for routine laboratory monitoring and dose adjustments.