Abstract A43: Recruitment and retention success of African Americans in a vitamin D supplementation trial
Authors: Drake Bettina F. , Scott Jamil B. , Gonzalez-Suarez Elizabeth , Emmons Karen M. , Giovannucci Edward , Fuchs Charles 
Published: December 2010

Purpose: The purpose of this abstract is to describe the recruitment and retention success of a double-blind, randomized-controlled vitamin D supplementation trial enrolling African American (AA), English-speaking participants between the ages of 30 and 80 in the Boston area.

Background: This study addresses the critical areas of cancer prevention and racial disparities by defining the optimal dose of vitamin D supplementation in AAs needed for future large intervention efforts in the prevention of colorectal cancer. AAs are at higher risk of colorectal and other gastrointestinal cancers, and compelling evidence suggests that the high rates of hypovitaminosis D in AAs may possibly account for this disparity in cancer incidence. Although the optimal dose of supplemental vitamin D needed to achieve adequate levels of plasma 25(OH)D is unknown in virtually all populations, there is a critical need to define doses of oral vitamin D supplementation in AAs that will achieve a sufficient level of plasma 25(OH)D before vitamin D chemoprevention studies are initiated. Study subjects were randomized to placebo, 1000 IU, 2000 IU, or 4000 IU of vitamin D3 per day to determine the minimum dose of vitamin D needed to achieve an optimal level. Supplementation occurred during the winter months, to reduce sun exposure. After 3 months of supplementation, plasma levels of 25(OH)D are determined and compared to baseline levels. We also assessed vitamin D levels 3 months post supplementation.

Methods: The recruitment goal was to enroll 320 participants, including100 men, into the study. A 3-phase eligibility and consent process was used to reach this goal. 1) Only people who were AA, English-speaking, and 30-80 years old were approached to participate in the study. 2) Among these individuals, basic nonclinical eligibility criteria were assessed. 3) Primary care physicians of the remaining individuals were contacted to assess clinical eligibility. Targeted recruitment efforts focused on obtaining individuals who met the first-phase eligibility criteria. Potential participants were identified at public housing sites, faith-based organizations, community organizations, and through participant referrals. To encourage retention, a case-manager approach was implemented and research assistants made biweekly phone calls and monthly pill bottle exchange visits with participants.

Results: Through our recruitment efforts, we consented 572 individuals and exceeded our recruitment goals with 329 participants enrolled in the study, including 107 men. During year 1, with 2.5 months of recruitment, we enrolled 46 participants. During years 2 and 3 with 6 months of recruitment each year, we enrolled 166, and 117 participants, respectively. Retention for the 3-and 6-month assessment was 90.1 % and 87.4%, respectively.

Conclusions: The number of individuals needed to be approached was about twice the desired amount of participants to be enrolled in the study. The design of this study posed many challenges for recruitment and retention; however, through collaborations with community-based organizations and biweekly contact with study participants, we were able to surpass our goals. Our strategies and lessons learned are relevant to other researchers conducting research in a population, such as this one, that has historically been challenging to recruit and retain into clinical studies.

Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):A43.