Improving the outcomes of anticoagulation

A number of studies have indicated that adverse events from anticoagulants are significant contributors to health care system expenditure. Adverse events comprise three groups: under-use, over-use and misuse. In Australia, it was estimated in 1992 that adverse events from warfarin cost $100 million in direct hospital costs alone. Part one of this thesis gives an overview of atrial fibrillation (AF) and the use of antithrombotics. This part provides comprehensive background on the significance of AF and its contribution to stroke and details the extensive evidence of antithrombotic drug efficacy in the prevention of stroke in AF. Despite overwhelming evidence that antithrombotics are effective in reducing the risk of stroke in AF, they remain under-utilised. Studies conducted internationally and nationally have shown that, in general, less than half of eligible patients receive anticoagulants. Described in part two of this thesis is two studies aimed at improving the use of antithrombotics for stroke prevention in AF. A nationwide survey of a random sample of general practitioners (GPs), cardiologists and other specialists was undertaken assessing barriers to the use of anticoagulants for stroke prevention in AF. This survey identified a number of key barriers to the use of anticoagulants and identified a number of key interventions to improve the prescribing of anticoagulants. Targeting the identified barriers to the use of anticoagulants, an educational intervention directed at GPs was initiated, aimed at improving the prescribing of antithrombotics in AF. The educational intervention utilised mailed guidelines and the process of academic detailing. The effect of the intervention was analysed using a controlled before and after study design. The educational intervention significantly improved the use of anticoagulants, but recognised that there is still significant room for more improvement. Findings of the nationwide survey of doctors identified portable International Normalised Ratio (INR) monitors as a key intervention to improve the prescribing of anticoagulants in AF, and improve the management of existing patients on anticoagulants. Part three of this thesis evaluated the use of portable INR monitors in three practice settings: an outpatient hospital anticoagulant clinic, rural general practices and rural community pharmacies. The portable INR monitors performed well in these three settings. They were found to give accurate and reproducible results when compared to pathology testing and the use of the monitors was well received by GPs, community pharmacists and patients. Findings from these three studies show that the use of portable INR monitors has the potential to significantly reduce health care expenditure associated with anticoagulant therapy, and provides a number of alternative models for anticoagulant management in the community setting. The final part of the thesis was an intervention aimed at reducing the incidence of bleeding complications amongst patients commenced on warfarin in hospital and discharged to GP care. Patients were randomised to a control or intervention group, where the control group received standard care from their GP and the intervention group received education after discharge and alternate day INR monitoring using a portable INR monitor for four visits after discharge. The intervention significantly reduced the incidence of bleeding complications assessed 90 days after initial discharge, and provided a reproducible model of care for patients commenced on warfarin in hospital and discharged to the community. The body of work conducted in this thesis provides a number of system solutions aimed at reducing the incidence of anticoagulant-related misadventure and under-use. It is clear that while this thesis provides preliminary evidence that adverse events associated with warfarin can be reduced, more work targeting the use of portable INR monitors in the initiation of warfarin therapy and transfer to the community setting, and education for stroke prevention in AF should continue.