Recruitment of mid-life adults to a randomized clinical trial: The multicultural healthy diet study to reduce cognitive decline and Alzheimer's disease risk.

introductionPoor representation of racial/ethnic minority groups limits the validity and generalizability of clinical trials and contributes to inequities in medicine and science.

objectivesTo recruit a multicultural sample of mid-life individuals using multiple recruitment modalities for a randomized controlled trial of diet and cognition comparing an anti-inflammatory dietary intervention versus usual diet and the effect on cognition.

methodsThis study describes the utility of various modalities to recruit a multi-cultural cohort. Recruitment techniques, the success rate of each, and characteristics of participants are compared to representative Bronx U.S. Census statistics. Participants were identified in target communities using voter registration rolls paired with marketing lists and enriched patient lists extracted from electronic health records of mid-life (40-65 years) adults in Bronx, New York. Outreach activities, including print and social media, supplemented these lists to promote the study.

resultsOver 4 years of recruitment, invitation letters, followed by telephone calls, yielded the highest number of randomized recruits, with 80.5% of participants recruited prior to the pandemic and 90.1% during the pandemic. A total of 290 participants enrolled in proportion to the racial/ethnic breakdown of targeted Bronx communities. However, women were overrepresented compared to the overall Bronx population. Each recruitment modality had strengths and weaknesses. The combination resulted in reaching an important sector of the population that could benefit from interventions. Voter registration lists reached a broad spectrum of targeted communities and resulted in enrollment and randomization of the majority of participants. Online registries (e.g., ResearchMatch) and outreach activities yielded efficient enrollment. DISCUSSION: Our multi-pronged strategy led to successful enrollment of a multi-cultural sample. Although the systematic list approach was the most productive, the importance of reaching out to community was crucial. Refining techniques of online registries, working with trusted community organizations, continuous assessment, and experimentation with other modalities may be helpful. Highlights: ADRD affects US minority populations disproportionately.Multiple recruitment methods help engage the underrepresented in clinical trials.Use of voter registration and EHR lists allow recruiters to reach a wide and heterogenous audience.Letters followed by personal phone calls are effective in recruitment.Outreach to the community provides a person-to-person connection to the study.