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

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.

Experienced Māori researchers were involved in trial governance throughout trial development and conduct. The trial Steering Committee included leading Māori researchers and was committed to equal recruitment of Māori and non-Māori. Additional funding and Māori research nurses were sought to allow home-based assessment, establishment of the relationship between research nurse and participant, more family involvement prior to enrollment, continuity of the research nurse-participant relationship, and acknowledgement of other Māori culturally important procedures, interactions, language and manners. Primary care practices with high enrollment of Māori were targeted, with over-sampling of potentially eligible Māori patients, lower thresholds for screening of Māori and 6 months continued Māori recruitment after non-Māori recruitment had finished.

A total of 257 Māori and 256 non-Māori participants were randomized. Four Māori and eight non-Māori participants were randomized per research nurse per month. Potentially eligible Māori were more likely than non-Māori to proceed to subsequent stages of recruitment. Differences between randomized Māori and non-Māori were evident (e.g. Maori were less likely to have established coronary artery disease).

Recruitment of equal numbers of indigenous and non-indigenous participants is possible if it is prioritised, adequately resourced and self-determination is supported.

The trial is registered with the Australian New Zealand Clinical Trial Registry ACTRN12606000067​572