Data on aspirin lacking

THE re-education of primary care providers and patients about the risks and benefits of taking aspirin for primary and secondary prevention of cardiovascular disease is happening, but slowly, according to the head of the national organisation advising on quality use of medicines.

Dr Janette Randall, chair of the board of NPS MedicineWise and a practising GP, said there was still a gap in the application of clear evidence in favour of using acetylsalicylic acid (ASA) in secondary prevention. “The data here in Australia is not very comprehensive, and that’s the biggest problem”, she told MJA InSight.

Dr Randall said research published earlier this year in Canadian Family Physician rang true in an Australian setting, although data were hard find. (1)

The Canadian research found that, of patients taking ASA for primary prevention of heart disease, 62.8% did so on the advice of their GP. This was despite the fact that “the literature does not show a net clinical benefit to using ASA for primary cardiovascular prevention”.

Among patients who decided to take ASA on their own initiation, only 3.5% were doing it for secondary prevention, the authors wrote.

In a recent interview with theheart.org, the lead author, Dr Michael Kolber, said “we’re actually missing the boat”. (2)

“It is likely that many patients of relatively low cardiovascular risk are taking ASA for primary cardiovascular prevention, while many of those who might benefit from ASA for secondary prevention are not taking it”, Dr Kolber said.

Dr Randall agreed, telling MJA InSight: “The big message for me is in the numbers who are not taking ASA for secondary prevention.

“Our gut instinct is that there are people who would benefit from taking aspirin but it is hard to target them because we don’t know who they are and why they are not taking it. Are they on other anticoagulants? Do they have adverse responses to aspirin? We just don’t know.”

Dr Randall said many people who took ASA had been doing so for a while, based on advice from their GP several years ago.

“That was probably quite reasonable [advice] to start with”, she said. “It highlights the need to review patients’ medications and history very regularly.

“De-prescribing a medication — stopping the patient taking it — is just as appropriate as it is to start them on one. It’s something that we’re not very good at yet.”

Dr Randall said GPs often lacked confidence to question treatment prescribed by a specialist if they felt it didn’t gel with the latest evidence.

“How do we empower GPs to go to the data and the evidence in order to provide an alternative for their patients? There’s a reluctance to challenge specialists and that’s a cultural thing”, she said.

NPS MedicineWise has used federal government funding to set up MedicineInsight, a data collection project accessing the prescribing data from 500 Australian practices. (3)

“Post-market surveillance data is very lacking in this country”, Dr Randall told MJA InSight.

“We’re 12 months into this project and we’re hopeful the data will help us to be more sophisticated with the way we target treatment.”

- Cate Swannell

1. Can Fam Physician 2013; 59: 55-61
2. theheart.org 2013; Online 28 March
3. NPS MedicineWise: MedicineInSight

Posted 8 April 2013