Authors' objectives: Antiplatelet drugs are used to prevent heart disease and stroke. They work by preventing the formation of blood clots in arteries. Blood clots happen when platelets (cells in the blood) clump together at the site of an injury to stop bleeding. Diseased arteries, such as those affected by fatty deposits (atherosclerosis), are particularly susceptible to blood clots. In people who have had a heart attack or have diseased arteries, low-dose aspirin (75 mg daily) is recommended indefinitely to prevent another heart attack or a stroke. People who have had a coronary stent put in one or more of their arteries or have had coronary artery bypass grafting (CABG) surgery following a heart attack are prescribed low-dose aspirin and an additional antiplatelet drug, most commonly clopidogrel (Plavix), less commonly prasugrel (Effient) and ticagrelor (Brilinta) for up to 12 months following the event. After this period of combined treatment, antiplatelet treatment is continued with low-dose aspirin alone. Combined treatment with aspirin and another antiplatelet drug is called dual antiplatelet therapy (DAPT). Some patients (e.g. those with atrial fibrillation) are also prescribed an anticoagulant (e.g. warfarin, dabigatran, rivaroxaban, or apixaban) in addition to DAPT. Antiplatelet therapies increase the risk of bleeding. Taking an anticoagulant on top of DAPT further increases bleeding risk. About 1 in 100 people on aspirin and 2 in 100 people on DAPT have a major bleeding event that requires hospitalisation. However, many more people (about 9 in 100) experience minor bleeding, such as bleeding in the stomach or bowel, and nuisance bleeding, such as nosebleeds, bleeding from gums, and excessive bruising. These minor bleeding events cause discomfort and anxiety, take up consultations with GPs and may cause patients to stop taking their tablets as prescribed. Few studies have assessed how often bleeding events happen in people taking DAPT. Hospital doctors (cardiolgists and surgeons) are increasingly prescribing more potent antiplatelet therapy to people who have had a stent or CABG surgery, without taking into account the risk of minor bleeding. They are doing this mainly because they do not know the extent of minor bleeding and the effect that it has on patients. This information is not known because most minor bleeding events are treated by GPs and patients do not go to hospital. Currently, decision-makers such as the National Institute for Clinical Excellent (NICE) are uncertain about the risk of minor and nuisance bleeding in people who take DAPT. Therefore, they cannot take it into account when making recommendations about which antiplatelet drugs should be used in people with heart disease and how long these drugs should taken for. We propose to use a large GP database of routinely collected data, and a database of describing patients attendances and admissions to hospital, to determine how many people experience bleeding after being prescribed DAPT or DAPT and an anticoagulant. We will compare patients who take aspirin only with patients taking different combinations of DAPT (with or without an anticoagulant). We will do this for different patient groups (treated with stent, CABG surgery or medication only). We will revise existing economic models of the cost-effectiveness of DAPT to take into account the rate of all bleeding events in people who take these medications. We will also review the literature to determine how bleeding affects quality of life in these individuals. Information from our study will help doctors to choose drugs that are more appropriate for individual patients specific needs, which will reduce the risk of bleeding and increase adherence to treatment.

Project Status: Ongoing

URL for project: http://www.nets.nihr.ac.uk/projects/hta/1419289

Anticipated Publish Date: 2021

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: England, United Kingdom

Organisation Name: NIHR Health Technology Assessment programme

Contact Address: NIHR Journals Library, National Institute for Health and Care Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK

Contact Name: journals.library@nihr.ac.uk

Contact Email: journals.library@nihr.ac.uk

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