The use of aspirin and dipyridamole in the treatment of acute ischaemic stroke/transient ischaemic attack: an audit-based discussion

The National Institute for Health and Clinical Excellence (NICE) recommends combination therapy (low dose aspirin plus modified-release dipyridamole) for all ischaemic strokes and transient ischaemic attacks (TIAs), for secondary prevention. Combination therapy is recommended for two years and thereafter low dose aspirin alone.¹

The first such audit at Withybush General Hospital in Haverfordwest was carried out in 2007 and was published as a clinical letter in this journal.² The practice has since been re-audited.

In the re-audit, 108 inpatients were included and data were collected on a proforma.

Eighty-nine patients (82%) presented with a first episode and 19 (18%) with recurrence. Of the 89 patients, 47 (53%) were prescribed the combination therapy and 20 (22.5%) were given aspirin only. Twelve were on warfarin, three on aspirin + warfarin, four on aspirin + clopidogrel and two on clopidogrel only. In the 2007 audit, 12% had combination therapy and 71% aspirin alone.

In the recurrent disease group, seven (37%) were on combination therapy compared to 16 (62%) in 2007 while four (21%) were on aspirin alone. Six patients were on warfarin, one on aspirin + warfarin and one on aspirin + clopidogrel.

Only three out of 54 patients on combination therapy were instructed to discontinue dipyridamole after two years.

Additionally e-questionnaires were sent to consultants and specialist registrars in elderly care medicine units throughout Wales asking the following questions:

• What antiplatelet do you prefer to use for first ischaemic stroke or TIA?

• What are the reasons if the combination of aspirin and dipyridamole is not being used?

• How long do you use dipyridamole for?

Out of 95 questionnaires only 20 (21%) replies were received, compared to 51% in 2007. Thirteen (65%) doctors used combination therapy while seven (35%) used aspirin alone following first event, compared to 22% and 30% respectively in 2007. Reasons for not prescribing combination therapy included non-inclusion in hospital formulary (1), lack of evidence (2), adverse side effects (2), and preference to commence combination therapy following a second event.

The results show a significant improvement in the use of the combination therapy following an ischaemic event between 2007 and 2008 in Withybush Hospital (Table 1). However the majority of patients (94%) were not clearly informed about treatment duration. The poor response from the geriatric consultants and specialist registrars in Wales to the questionnaires may be due to a deluge of questionnaires from other studies or could be due to the fact that the same questions were asked previously.

In July 2008, NICE issued guidance suggesting that all patients presenting with an acute ischaemic stroke should be started on 300 mg aspirin within 24 hours and that this should be for two weeks. Definitive long-term antithrombotic treatment should then follow.³

• © 2009 Royal College of Physicians