Who is responsible for the care of patients treated with warfarin therapy?

Objective: To identify potential weaknesses in the system of managing warfarin therapy.

Design, Participants And Setting: A structured interview-based study of 40 community-dwelling patients taking warfarin and with an international normalised ratio > or = 6.0 and 36 of their treating doctors (35 general practitioners and 1 specialist), conducted between July and November 2007. Patients all received services from and were recruited sequentially by a large, private metropolitan pathology provider in Melbourne.

Main Outcome Measures: Patients' demographic, clinical, cognitive and psychosocial characteristics, warfarin knowledge, medication complexity and adherence; and doctors' experience with, approach to and involvement in warfarin management, and their perception of responsibility for warfarin management and patient education.

Results: Interviews revealed multiple difficulties, including cognitive dysfunction, possible depression, and medication non-adherence, in 30 of 40 patients. Of 36 doctors interviewed, 12 were unaware of these difficulties in their patients. Five doctors considered they had sole responsibility for their patients' anticoagulation, while 15 confirmed a mutual relationship with the pathology service, and 16 deferred total responsibility to the pathology provider. Only 14/36 doctors reported conducting patient education at commencement of warfarin therapy, with the other 22 stating this was the responsibility of the initiating specialist, pathology service or dispensing pharmacist.

Conclusions: There is a need for improved role clarification in coordinating warfarin management. We propose exploring the possibility of a Warfarin Suitability Score to assist better recognition of patients in whom treatment may be problematic, along with a model of care using practice nurses with GPs to facilitate optimal patient care.