Heart attacks and strokes (cardiovascular diseases, CVD) cause many early deaths in New Zealand, particularly among Maori. Combination therapy with aspirin, cholesterol-lowering and blood pressure-lowering medicines can halve a person's risk of CVD but many who could benefit are not receiving or taking all these medications. A trial is underway to assess whether a single pill that combines these medicines (a 'polypill') improves medicine-taking over 12 months compared with receiving the medicines separately, as is the usual practice. In partnership with three District Health Boards (DHBs) we aim to measure the costs of treating people at high risk of CVD with 'usual' care compared with the 'polypill', and obtain detailed information about patient and doctor medication practices over a longer time frame (up to 3 years). This will help DHBs determine how to improve the medication management of CVD among high-risk patients, including Maori, who comprise half the trial participants.