ANTICOAGULATION prescribing rates in rural and remote Western Australia are approaching the global average thanks to increasing acceptance of non-vitamin K antagonist oral anticoagulants (NOACs), according to research published in the MJA.
The vitamin K antagonist warfarin was the predominant anticoagulant used for preventing stroke in patients with venous thromboembolism or non-valvular atrial fibrillation until the introduction of NOACs, which were approved for similar use in Australia by the Therapeutic Goods Administration in April 2011.
Because of its highly variable metabolism, warfarin requires regular monitoring to ensure that its blood levels remain in the therapeutic range at least 55% of the time . In a country where 29% of the population lives in rural or remote areas, access to health services can be problematic in some parts of Australia. For patients on warfarin, that can mean less than optimal anticoagulant therapy.
Researchers from the Royal Perth Hospital, Bunbury Regional Hospital, South West Health Campus, and the University of Western Australia had three main aims:
- to determine the use of different anticoagulation therapies in rural Western Australia;
- to assess whether remoteness from health care services affects the choice of anticoagulation therapy; and,
- to gather preliminary data on anticoagulation therapy safety and efficacy
They conducted a retrospective cohort study of patients hospitalised with a principal diagnosis of atrial fibrillation/flutter (AF) or venous thromboembolism (VTE) during 2014–2015 in four hospitals serving two-thirds of the rural population of WA. They identified 609 patients with an indication for anticoagulation therapy recorded in hospital discharge summary for index admission.
Dr Jamie Bellinge, a research fellow at Royal Perth Hospital, and a PhD candidate in cardiology at UWA, told MJA InSight in an exclusive podcast, that the overall rates of prescription of NOACs and warfarin were similar (34% v 33%), but that NOACs were more often prescribed for patients with AF (56.0% v 42.2%) and that warfarin was more often prescribed for patients with VTE (48% v 29%).
“We think that difference is because VTE is a relatively new indication for the use of NOACs,” Dr Bellinge said. “NOACs have been used for stroke prevention in VTE only for about 3 years. That lag is likely to be [the reason] for slower uptake for that indication.”
The researchers also found that 31% of patients with indications for anticoagulant therapy walked away from hospital without a prescription for either warfarin or NOACs.
“Only 69% were prescribed anticoagulants,” Dr Bellinge said. “That appears quite low, but this data suggests that rates are improving. Data from the late 1990s and early 2000s showed prescribing rates were as low as 27%. In 2011, in a rural cohort in Queensland, they found a prescribing rate of 51%.
“Considering that the global rate of prescribing anticoagulants currently sits at about 72%, we should be quite happy with [69%].”
The researchers also found that warfarin was prescribed for 38% of patients who lived locally — that is in the town where their hospital or GP was based — and a NOAC was prescribed for 31%. For non-local patients, the respective proportions were 29% and 36%. Patients from outside the region were more often prescribed a NOAC than warfarin (43% v 9%).
“This makes sense,” Dr Bellinge said. “Patients in the town where they were admitted to hospital are more likely to get warfarin than NOACs because they have easier access [to regular monitoring].
“As patients live in more remote settings, they tended to be prescribed NOACs.
“This is promising because it suggests that rural practice is tending towards accepting the safety and tolerability of NOAC therapies. In terms of safety, although a lot of the data comes out of urban settings, seems to have translated reasonably well into rural areas. Rural physicians seem to be [becoming] comfortable with prescribing NOACs.”
During the course of the study, bleeding events were more common among patients treated with warfarin than those treated with a NOAC (10% v 4%).
“That’s also promising, and may assist in promoting the prescribing of NOACs in rural cohorts,” Dr Bellinge said.
The transfer of evidence-based knowledge to clinical settings in remote and rural areas “remains difficult”, the researchers wrote.
“We know that, in general, the transfer of evidence-based knowledge into practice takes time,” Dr Bellinge told MJA InSight.
“Rurality and remoteness add a new component to this potential delay. Yes, there is increased access in resources, but there does still appear to be delays. There is still significant room to improve.
“We need to increase awareness and promotion of anticoagulation therapy, particularly in these areas where it does take time.
“Atrial fibrillation is the most preventable cause of stroke by prescribing anticoagulation.
“Keep NOACs in mind – they are the more favourable choice throughout urban populations, and the evidence is there for rural cohorts.”
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