Comprehensive ascertainment of bleeding in patients prescribed different combinations of dual antiplatelet therapy (DAPT) and triple therapy (TT, DAPT plus an anticoagulant) after coronary interventions in the UK: a population based cohort study
Funder: NIHR/HTA (project number 14/192/89)
Sponsor: University Hospitals Bristol
Antiplatelet drugs are used to prevent heart disease and stroke. They work by preventing the formation of blood clots in arteries.
In people who have had a heart attack or have diseased arteries, low-dose aspirin (75 mg daily) is recommended to prevent another heart attack or a stroke. People who have had a coronary stent or coronary artery bypass grafting (CABG) surgery following a heart attack are prescribed low-dose aspirin and an additional antiplatelet drug, for up to 12 months following the event. This is called dual antiplatelet therapy (DAPT). Furthermore, some patients (e.g. those with atrial fibrillation) are also prescribed an anticoagulant (e.g. warfarin, dabigatran, rivaroxaban, or apixaban) in addition to DAPT, which is known as ‘Triple Therapy’.
Antiplatelet therapies increase the risk of bleeding, from minor bruising to more severe symptoms such as gastrointestinal bleeding. Few studies have assessed how often bleeding events happen in people taking DAPT. Hospital doctors are increasingly prescribing more antiplatelet therapy to people who have had a stent or CABG surgery, without taking into account the risk of minor bleeding. The extent of minor bleeding and the effect that it has on patients is not known because most minor bleeding events are treated by GPs and patients do not go to hospital.
The ADAPTT study will use a large GP database of routinely collected data, and a database of 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) and will look into the cost-effectiveness of DAPT. We will also review the literature to determine how bleeding affects quality of life in these individuals. Information from the ADAPTT 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.
Chief Investigator: Dr Maria Pufulete, Research Fellow