Black art posters, an incentive to increase study enrollment among Blacks in a large cohort study

Objective: Black art posters were offered to replace or augment the established $10 incentive for questionnaire completion in a longitudinal cohort study. Method: Eighty-one churches located in the US southern region were divided between two intervention groups, with a control group of 24 churches from the same region. Primary outcome measures were study enrollment rates and questionnaire return rates between December 2003 and July 2004 as a proportion of church goal. Results: 9.3% of participants returning questionnaires selected a poster in preference to $10. Half of participants offered both monetary and art incentives indicated a poster selection. Crude questionnaire return rates were 57.4% for the pooled intervention churches and 38.2% for the control churches. Enrollment rates among those offered both incentives were significantly higher (p < 0.01) than when monetary incentives alone were offered after adjustment for church size, promotional dates, and average income of church members. Survey return rates were also higher in the churches offered both incentives (p = 0.04). Conclusion: These data suggest that the black art posters improved study enrollment and survey return rates. The relatively low rate of poster selection suggests that the art primarily influenced participation indirectly, by creating a more culturally inclusive image of the study.