General cardiology

ABPI cannot be used to determine primary prevention benefit from aspirin

A low ankle brachial index (ABI) indicates the presence of atherosclerotic arterial disease, and therefore an increased risk of cardiovascular and cerebrovascular events. Screening for a low ABI may therefore identify a group of asymptomatic subjects who may benefit from preventive treatments. The Aspirin for Asymptomatic Atherosclerosis (AAA) trial was therefore established to investigate the effectiveness of aspirin in preventing cardiovascular events in patients with a low ABI.

Over a 10-year period, 28 980 men and women between the ages of 50 and 75 years were recruited and screened with an ABI test. Of these, 3350 patients with a low ABI (<0.96) were recruited and randomised to treatment with either 100 mg aspirin once daily or placebo. After a mean follow-up of 8.2 years, 357 participants had a primary end-point event (a composite of initial fatal or non-fatal coronary event or stroke or revascularisation). No statistically significant difference was found between the two treatment groups (13.7 events per 1000 person-years in the aspirin group vs 13.3 in the placebo group). Similarly, no difference was seen between treatment groups in the secondary outcomes or in all-cause mortality. However, an initial event of major haemorrhage requiring admission to hospital occurred in 34 participants …