Skip navigation

Increasing aspirin use for secondary prevention of IHD


Although the benefits of aspirin in reducing risk for patients with heart disease are well known many patients do not receive daily prophylactic aspirin. It is one of the dilemmas facing those who promote evidence-based practice. It's a strong contender for action and success should be assured. But, what is the most practical approach to increasing the prescribing of aspirin? A study [1] by a research team in North London explored the provision of data on aspirin prescribing to general practitioners as a means to stimulate better prescribing with some success.


Peter McCartney and colleagues. A randomised controlled trial of feedback to general practitioners of their prophylactic aspirin prescribing. BMJ. Vol. 35, 5 July 1997, 35-36.

How was the question tackled?

The research team approached 48 practices in North London and 28 agreed to take part. (9 refused and 11 were unsuitable). 7 of the practices were single-handed and 6 had five or more partners. A precondition of involvement in the trial was that practices were using computer systems to manage their records: 2 used Paradoc and the others used EMIS. The practices were randomised to two groups to receive feedback on their prescribing, either of aspirin for patients with ischaemic heart disease (the intervention group), or of hormone replacement therapy for women who had hysterectomies (the control group). Data was collected for both aspirin and hormone replacement therapy in all practices at baseline and follow-up (at least three months later).

Time was set aside at practices meetings for the team to provide feedback on the baseline data and advice about the evidence to support the use of aspirin. PG educational approval was given for the meetings. Practices were then encouraged to review the care for patients not apparently taking aspirin. Their local Medical Audit Advisory Group (MAAG) provided support.

What did the trial show?

There were 14 practices in each arm of the trial (with a total of about 180,000 patients). The search of records identified about 2800 heart disease patients, of whom about 1400 were taking aspirin. No important discrepancies were discovered when a manual search was made to check whether the computer systems were reliable.

Later analysis of the data showed that prescribing rose encouragingly in the intervention group from about 48% to about 58%: the change in the control group was a rise of about 1% (from 49 to 50%). The practices in the aspirin arm of the trial were reminded about recording patients 'buying aspirin over the counter' but those in the hormone replacement arm were not. These records were ignored when the results were being measured. Patients' records showed that about 5% of patients bought their aspirin over the counter.

Some of the apparent increase may be due to improved coding - systems get better when they are used - but only a small proportion (2%) of ischaemic heart disease patients had only a written record and about 5% of patients were buying their aspirin over the counter.

The feedback of information increased the proportion of patients with ischaemic heart disease by about 9%. Research shows that aspirin use in 86 high-risk patients prevents one death in two years. If the success in this trial were replicated across the UK it could reduce mortality from ischaemic heart disease by about 1100 deaths every two years. For example, in practices similar to those involved in this trial feedback to 20 general practitioners (number of doctors needed to treat) would be needed to prevent one death from ischaemic heart disease in two years.

What has the trial told us?

This small trial has demonstrated, yet again, what can be achieved if resources are available to bring specific interventions to the notice of busy clinicians. The combination of proven techniques - information (about current practice) with education (about an evidence-based approach) - was effective.

But we cannot rely on trials and projects to stimulate these improvements in clinical practice. Ways have to be found to inject a more systematic approach, which makes it possible for all clinicians to review their practice as a matter of course. It's about making quality improvements in their practice the goal of all clinicians and about making organisations capable of implementing systems that provide the support needed. This means making management and costing information, knowledge management, education and patient records systems work as parts of one integrated whole.