This study demonstrated that African-American smokers can be successfully recruited to participate in an intensive GCRC-based non-treatment study. Given the intensity of participation required for the study, including 24-hour urine collection, the use of cigarette and pill monitoring devices, the number and duration of study visits, and multiple blood draws, achieving this recruitment level was considered a success. This outcome supports the feasibility of including African-Americans in laboratory-based research. Showing that African-Americans will volunteer to enroll in this type of research is important, given the persistent national problem of underrepresentation of African-Americans in clinical studies [10
]. The recruitment goal of the study was to have 40 African-Americans complete the pharmacokinetic study. We screened 515 and identified 187 eligible African-American smokers. Of 81 individuals scheduled for the medical screening (Visit 1) at the GCRC, 49.4% completed the full PK study. It should be noted that it took approximately 12 months to meet this enrollment goal, a much longer time than is needed to recruit the same number of smokers in most smoking cessation studies [34
]. This discrepancy is likely due to the intensive nature of the protocol as well as the location of the study. This study was located in an academic medical center and most of our participants heard about the study through newspaper advertisement. This is a departure from our previous study in a community health center serving a predominantly low-income African-American population. In that study, word of mouth yielded more participants [37
]. Our advertisement strategies also played a role. Periodically, we reviewed progress with recruitment methods and invested more in newspaper advertisement, which proved to be more effective compared to other sources.
Multiple factors contributed to recruitment success. Our research team has a track record of successfully engaging African-Americans in research studies, and we applied this experience to our recruitment efforts [32
]. We emphasized cultural competence and cultural sensitivity training within our research team. We involved the African-American community and health care providers through a Community Advisory Board in the planning and execution of our projects [34
]. Our efforts in the community have progressively built trust, which is critical given that lack of trust is a major impediment to the participation of African-Americans in medical research studies [12
]. We integrated recruitment tracking mechanisms to maximize retention of our participants. In this study, we achieved a relatively high retention rate of 83%. Of the 48 participants who met final eligibility criteria and enrolled in the pharmacokinetic study, 40 participants completed the study. This rate is similar to the retention rates of 84% we obtained in our previous clinical trials [52
], but lower than 90%, reported in a more intensive long-term clinical trial involving African-Americans with renal insufficiency [55
]. This implies that retention might be better in a treatment-seeking population than in a non-treatment-seeking population.
The recruitment of African-American non-menthol smokers into our study was particularly challenging. Only about 20% of African-American smokers smoke non-menthol cigarettes [29
]. Because of the lower prevalence of African-American non-menthol smokers, we could not enroll eligible menthol smokers until we found non-menthol smokers who could be matched with menthol smokers. Consequently, we had a long waiting list of menthol smokers who, although eligible for the study, could not be enrolled due to lack of a non-menthol match. This sampling technique is prone to selection bias and may limit the generalization of our study findings. This limitation speaks to methodological challenges pertaining to research involving menthol and non-menthol African-American smokers.
The majority of the participants who were excluded from this study after the informed consent process either did not adhere to medication regimen or did not keep the scheduled appointment. We do not know if failure to attend visit during the abstinence phase was due to the fact that some of the smokers could not stop smoking during this phase. While the exclusion criteria were carefully chosen to remove individuals who seemed unlikely to comply with our protocol, this study also provided insight into issues that warrant further investigation, such as adherence to medication among minority populations, and factors that influence minority participants to not keep the study appointments. Illicit drug use (primarily marijuana) accounted for 19.5% of those who were excluded from study after consenting to participate. Although use of illicit drugs was a clear exclusion criterion, we administered this question in person because of its sensitive nature and the need to get more accurate information along with a certificate of confidentiality on their behalf from the federal government agency for their protection.