NICE guidance (NG28) released on 15th December 2015 changed the advice regarding aspirin use to: ‘Do not offer antiplatelet therapy (aspirin or clopidogrel) for adults with type 2 diabetes without cardiovascular disease.’ This has raised the question as to whether patients already taking aspirin, in line with the previous NICE clinical guideline (CG87), should now stop (although NICE did not specifically recommend this action).
The guideline development group for NG28 focused on three studies of antiplatelet therapies, two of which provided new evidence. One was an unpublished post-hoc analysis of cardiovascular (CV) outcomes in the Early Treatment Diabetic Retinopathy Study and the second from a Japanese population, with notoriously low levels of CV events. The doses of aspirin used ranged from 61-650 mg, and the quality of the evidence was rated as between ‘moderate’ and ‘very low’.
New, high quality evidence will appear in the near future. NICE acknowledged the UK-based ASCEND trial, which includes 15,480 people with diabetes without occlusive arterial disease, which is scheduled to continue until 2017. NICE also highlighted another trial (ACCEPT-D) conducted in Italy which also aims to assess the effects of low-dose aspirin on major vascular events in people with diabetes and no clinical evidence of vascular disease. For this reason, NICE did not recommend further research in this area.
Other guidelines do not support change. The American Diabetes Association ‘Standards of Care’ 2016 continues to recommend consideration ‘of aspirin therapy (75–162 mg/day) as a primary prevention strategy in those with type 1 or type 2 diabetes who are at increased CV risk (10-year risk >10%). This includes most men or women with diabetes aged 50 years who have at least one additional major risk factor’- remarkably similar to CG87.
There is also evidence in the literature of a rebound effect from stopping aspirin i.e. an increased risk of ischaemic stroke in patients four weeks after discontinuation. Furthermore, duration of aspirin use is not a risk factor for bleeding, that is to say those patients who are established on aspirin are at low risk of its major side-effect.
This balance of risks should make practitioners very wary of change.
Professor Steve Bain