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Clin Trials. 2015 Jun;12(3):205-11. doi: 10.1177/1740774514568125. Epub 2015 Feb 2.

Outreach to diversify clinical trial participation: A randomized recruitment study.

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Division of Research, Kaiser Permanente Northern California, Oakland, CA, USA
Division of Research, Kaiser Permanente Northern California, Oakland, CA, USA.
Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, CA, USA.



Racial and ethnic minorities remain underrepresented in clinical research, yet few recruitment strategies have been rigorously evaluated.


We experimentally tested whether targeted recruitment letters acknowledging diabetes health disparities and health risks specific to recipients' racial/ethnic group improved two metrics of trial participation: willingness to be screened and enrollment. This experiment was efficiently nested within a randomized clinical trial examining a preventive lifestyle intervention among women at high risk for diabetes. Pregnant women with gestational diabetes or impaired glucose tolerance (N = 445) were randomized to receive a targeted recruitment letter with health risk information specific to their racial/ethnic group (n = 216), or a standard letter with risk information for the general population (n = 229). All letters were bilingual in English and Spanish.


The targeted as compared to the standard letter did not improve screening or enrollment rates overall or within separate racial/ethnic groups. Among Latina women who preferred Spanish, the targeted letter showed trends for improved screening (66.7% vs 33.3%, p = .06) and enrollment rates (38.9% vs 13.3%, p = .13). In contrast, among Latina women who preferred English, the targeted letter significantly lowered screening (29.6% vs 57.1%, p = .04) and showed trends for lowered enrollment rates (25.9% vs 50.0%, p = .07).


Results from this randomized study appear to suggest that recruitment letters with diabetes health risk information targeted to recipients' race/ethnicity may improve one metric of clinical trial participation among Latina women who prefer Spanish, but not English. Larger experimental studies, incorporating input from diverse participant stakeholders, are needed to develop evidence-based minority recruitment strategies.


Randomized clinical trials; communication; diabetes; direct mail; disease risk; health disparities; participation; racial and ethnic minorities; recruitment; targeting

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