Assessing the Risk-Benefit Ration of Aspirin for primary Prevention in Patients with Diabetes; Nilay Shah; ADA 2011.

There is no doubt that aspirin confers significant benefit as a secondary prevention agent in diabetes.

However as a primary preventioin agent there is substantial doubt about the efficacy of aspirin. There have been 5 systematic reviews of the benefit of aspirin in diabetes in the last few years. All of these showed that there was a slight (approx. 15-20%) RR benefit for aspirin but this does not reach significance. However in all of these reviews there was a clear and significant increase in the risk of severe bleeding due to aspirin.

This raises the question – can we recommend the routine use of aspirin as a primary prevention agent in diabetes? There are known gender specific differences in the types of event that aspirin prevents (eg MI in men versus CVA in women). The ongoing ASCEND and ACCEPT-D trials are very large and will hopefully give a clearer answer about the use of aspirin as a primary prevention agent and especially those groups who might derive primary benefit from aspirin.

Users of aspirin have better knowledge about the benefits of aspirin whereas non-users have been shown to have greater knowledge about the risks.

Thus there is a knowledge differential related to users versus non-users. Concordance is also a potential issue in patients who already take an average of 4 mediciations for their diabetes, especially as aspiring confers no symptom benefit at the tine it is taken.

Sussman et al (2011) have shown that in 54 million people treated with aspirin there will be a net gain of 670,000 QALY’s, but most of this gain is in those at higher risk 20-30% 10-year risk and there is very limited gain in those at lower (eg 10@%) 10-year risk.

The various guidelines offer conflicting advice and it is important to involve the patient in making a decision about aspirin therapy. For instance in a case with 11% 10 year risk there would be a risk of 3/1000 for sever bleeds and 15/1000 for CVD events prevented. These are NNT of 333 and 66 respectively.

There are limited data specifically related to low dose aspirin which makes it difficult to be exact about risk.