Minority recruitment into clinical trials: experimental findings and practical implications

Racial and ethnic minorities in the US suffer disproportionately from obesity and related comorbidities, yet remain underrepresented in health research. To date, research on practical strategies to improve minority reach and recruitment into clinical trials is primarily descriptive rather than experimental. Within a randomized behavioral weight management trial for obese women, this recruitment experiment examined whether two characteristics of direct mail letters, an ethnically-targeted statement and personalization, increased the response rate among minority women. The ethnically-targeted statement noted ethnic-specific information about health risks of obesity. Personalized letters included recipients' names/addresses in the salutation and a handwritten signature on high-quality letterhead. Of women sent direct mail letters (N=30,000), those sent letters with the ethnically-targeted statement were more likely to respond than women sent letters with the generic statement, 0.8% (n=121) vs. 0.6% (n=90) respectively, p=.03, a 34.4% increase. Women sent personalized letters were no more likely to respond than women sent non-personalized letters, p=.53. In the weight management trial itself, of 267 women randomized into the trial, 33.7% (n=90) were minorities. Of minority women randomized into the trial, 68.9% (n=62) were recruited by direct mail letters: 75.8% (n=47) of those were sent a letter and 24.2% (n=15) were referred by friends/family who were sent a letter. The results indicate that a simple modification to a standard recruitment letter can have a meaningful impact on minority reach and recruitment rates. Practical implications include using ethnically-targeted, non-personalized direct mail letters and recruiting through friends/family at no additional cost.