BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death, and 
principal reason for the large difference in life expectancy between indigenous 
Māori and the non-indigenous population in New Zealand. CVD guidelines recommend 
that people who are at high risk or who have had previous CVD should be offered 
aspirin, blood pressure lowering and lipid lowering therapies. However, 
prescribing and adherence rates are low and CVD events remain high.
AIM: To assess whether a medication strategy using a fixed dose combination pill 
('polypill') could improve prescribing and adherence to recommended medications, 
lower blood pressure and improve lipids compared with current care over 12 
months.
METHODS: IMProving Adherence using Combination Therapy (IMPACT) is an open-label 
randomised controlled trial comparing a once-daily polypill containing four 
preventive medications with usual care. Six hundred participants who have had 
previous CVD events or are at high risk of CVD will be enrolled, including 300 
Māori. Participants are identified, enrolled and prescribed either the polypill 
or current medications at their usual primary health care practice, with 
medications (including the polypill) dispensed through local community 
pharmacies. The polypill contains 75 mg aspirin, 40 mg simvastatin, 10mg 
lisinopril and either 12.5mg hydrochlorothiazide or 50mg atenolol. Primary 
outcomes are adherence to guidelines-recommended medications and changes in 
systolic blood pressure and low density lipoprotein at 12 months. Secondary 
outcomes include other lipids, medication dispensing, barriers to adherence, CVD 
and other serious adverse events, quality of life and prescriber acceptability. 
The trial is registered with the Australian New Zealand Clinical Trial Registry 
(ACTRN12606000067572).