Contrary to received wisdom, ethnic minorities can be recruited in high numbers to clinical trials and will in large part stay the course, a US analysis indicates.

While the report published in the online open-access journal BMC Public Health related specifically to behavioural research, its sharp contrast with previous findings on ethnic minority participation in clinical studies had wider implications for clinical recruitment and retention. In particular, it suggested that the right incentives, project design, subject matter, staffing and follow-up strategies can make a significant difference in achieving study goals.

A US team led by Dr Nabil El-Khorazaty of the Statistics and Epidemiology Unit at RTI International in Rockville, Maryland looked at the recruitment and retention of women of African American and Hispanic origin into a behavioural study (Project DC-HOPE) investigating whether counselling programmes were effective at reducing smoking, depression and partner violence during pregnancy. The women, who were all residents of Washington, DC, were followed up until 10 weeks post-partum.

Out of the 1,398 women identified through screening as eligible for the study, 1,191 (85%) agreed to participate in the study. Subsequently, 1,070 (mostly African American women) completed the baseline evaluation and were enrolled in the study, giving a recruitment rate of 90%.

A total of 849 women competed the study, a retention rate of 79%, with 5% dropping out and 12% lost to follow-up. While there were no statistically significant differences between the women retained and not retained in the trial with respect to socio-demographic characteristics and targeted risks, there were marked disparities between those who dropped out and those who were lost to follow-up.

For example, the women who dropped out were more educated, older, more likely to be married and employed, and less likely to be receiving Medicaid, suggesting these women may have “had more stable lives and viewed the study as less beneficial to them”, the researchers noted. Conversely, the women lost to follow-up tended to be less educated, unmarried, unemployed, younger and receiving Medicaid benefits.

For the first group, the authors commented, “the benefits of the study must consistently be reinforced throughout the duration of the study to prevent them from losing interest and dropping out”, while for the latter, “investigators should emphasise the need for obtaining accurate and complete contact information in order to be able to minimise non-retention as much as possible.”

Retention strategies

The high retention rate in the study was attributed partly to the financial compensation provided for the participants’ time and effort. Other strategies seen to improve retention were use of a data management system that tracked study events; the provision of timely tracking and monitoring reports for all study activities to maintain close communications; frequent telephoning of participants to keep them informed of upcoming interviews; building a rapport through sensitivity to the women and their experiences; and matching the recruitment specialists and pregnancy advisors to the study population in terms of gender and ethnicity.

The low attrition rate in Project DC-HOPE “indicates that difficulties in recruiting and retaining minorities for clinical and behavioural research are not insurmountable,” the authors concluded, adding: “With targeted recruitment and retention strategies, minorities will participate at high rates in these trials.”

This was an important goal, as the prevalence of many health problems was higher in these populations and health outcomes were often poorer, the researchers said. Not only did the inclusion of ethnic minorities in clinical and behavioural research provide better access to new and high-quality healthcare that was often not available to them, it also permitted the study of potential ethnic differences in disease pathology and improved the capacity to generalise research results, they pointed out.