Recruiting equal numbers of indigenous and non-indigenous participants to a ‘polypill’ randomized trial

Vanessa Selak, Sue Crengle, C Raina Elley, Angela Wadham, Matire Harwood, Natasha Rafter, Chris Bullen, Avinesh Pillai, Bruce Arroll, Anthony Rodgers

Māori are disproportionately affected by cardiovascular disease (CVD), which is the main reason for the eight year difference in life expectancy between Māori and non-Māori. The primary care-based IMPACT (IMProving Adherence using Combination Therapy) trial evaluates whether fixed dose combination therapy (a "polypill") improves adherence to guideline-based therapy compared with current care among people at high risk of CVD. Interventions shown in trials to be effective do not necessarily reduce ethnic disparities, and may in fact widen them. Indigenous populations with poorer health outcomes are often under-represented in trials so the effect of interventions cannot be assessed for them, specifically. Therefore, the IMPACT trial aimed to recruit as many Māori as non-Māori to assess the consistency of the effect of the polypill. This paper describes the methods and results of the recruitment strategy used to achieve this.