Karissa Arthur, MD
Enrollment of women and minorities into trials related to carotid disease is low, despite efforts to bolster recruitment of these groups. The Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial (CREST-2) therefore sought to improve recruitment of women and minorities via a screening program. Life Line Screening (LLS) is a nationwide private health screening organization which helps to identify adults at risk for serious vascular diseases via screening events in local communities across the United States. The investigators developed a partnership (CREST-LLS partnership) in order to enhance identification of asymptomatic carotid stenosis among women and minorities.
For the CREST-LLS partnership, all LLS screening events occurring within a 50-mile radius of a CREST-2 center were identified for participation over the course of one year. Each event evaluates 25-100 participants who are recruited via targeted emails, local television and radio channels, newspapers, and direct mail. Cost to the participant was variable and depended on pre-arranged sponsorships, union health plans, and the assessments selected by participants. Available assessments included blood pressure measurements, ankle-brachial measurements, ECG, and blood lipid levels. If participants were over 50 with at least 2 vascular risk factors, carotid artery duplex ultrasound was performed by trained and certified vascular ultrasound technologists. If ultrasound peak systolic velocity was greater than or equal to 230 cm/s, participants were suspected of having high-grade carotid stenosis. These participants were provided the findings and informed about the opportunity to be evaluated at the nearest CREST-2 clinical center. Their consent to be contacted by study coordinators was also requested by non-medical staff.
During the 12-month study period, the CREST-LLS program included 230,021 participants and 7,500 zip codes within a 50-mile radius of a CREST-2 clinical center. Most participants were women (60.3%) and White (78.4%), with 10.0% Black patients. The overall rates of abnormal carotid ultrasound findings ranged from 0.15 to 0.76% and varied by race and sex, with higher rates in men, Native American and White participants. Of the 230,021 participants screened, 646 were suspected of having high grade carotid stenosis. Of these, 200 consented to be contacted by the local CREST-2 center, but only 39 patients agreed to participate and were evaluated at a local CREST-2 center. Of those that agreed to evaluation, 33.3% were women, 87.2% White, and 7.7% Black. Of these 39 patients, 27 were confirmed to have >70% stenosis, though only 3 patients agreed to participate. One of the 3 was a woman, and none were racial/ethnic minority.
Overall, the CREST-LLS was able to identify 646 patients out of 230,021 individuals screened with carotid stenosis, despite the low prevalence. However, only 3 of those identified agreed to enroll in CREST-2, none of which were minorities and only 1 was a woman. Therefore, while the CREST-LLS program was successful in identifying patients who qualify for enrollment, it was not successful in recruiting for participation. The authors note the invasive intervention may have deterred participants from enrolling in the CREST-2 trial, especially given the diagnosis of carotid stenosis was new for most participants. Further, the authors note that the initial contact with eligible participants was made by non-medical staff who may not have been able to answer clinical questions and therefore deterred individuals from participating. However, only 39/200 patients contacted by medical staff agreed to the evaluation, despite their expertise in the CREST-2 trial. The researchers noted most of those patients preferred to be followed by their primary care physician, perhaps due to a stronger therapeutic relationship as well as location closer to their homes.
This study is an important step in understanding why women and minorities are often not recruited successfully in clinical trials. For example, more women were screened and agreed to be contacted by telephone than men, but fewer women agreed to be evaluated at a CREST-2 center than men. Minority participation decreased the most between the time of the screening and their agreement to be contacted by a CREST-2 center, perhaps representing their distrust of research or socioeconomic burdens which may make travel to a CREST-2 site difficult.
There were two main limitations in understanding the difficulty of recruiting women and minorities. First was the inability to assess the 400 patients who did not agree to be contacted to understand why they did not want to participate. Second was the lack of specific questions to identify other variables which affect participation such as education level, urban versus rural location, income, marital status, and transportation availability.
Despite these limitations, the authors developed an innovative way to identify asymptomatic patients in the community who have underlying vascular disease. Future studies to more thoroughly evaluate reasons for non-participation of women and minorities will add to this work.