The introduction of this informational video to the enrollment protocol for the Colorado clinical center of the TEDDY Study provided a quasi-experimental design in which we were able to assess this as a strategy that might improve enrollment rates and support early retention. Enrolling a representative cohort and retaining participants are critical for minimizing selection and drop-out biases, therefore increasing the generalizability of prospective study findings. The intent behind using an informational video was to improve potential participants’ understanding of the study protocol so that a better informed decision to participate could be made, as well as saving staff time and presenting the information in a standard format.
In this setting, we were able to demonstrate that being in the group that received the video in addition to the other elements of the enrollment protocol was independently and positively associated with increased enrollment rates of a pediatric cohort. There was an absolute 7% higher enrollment rate in the Video Group (56.9% vs. 49.9% of the No-Video Group). While adjusting for other known factors associated with enrollment, those who received the video were 37% more likely to enroll than those who did not receive the video.
With this analysis, it was also possible to assess early drop-out risk between those who did and did not receive the video. Although there was not a significant difference in retention rates between the two groups, the survival curves show a slight difference in a positive direction, indicating that while the video did not significantly improve retention rates, it appears to have had a slightly positive impact on retention.
A recently published analysis that included all clinical centers of the TEDDY Study (n=3,757) found that country of residence, young maternal age, lack of father participation and female gender of the child to be significant predictors of early withdrawal in the first twelve months of study participation in the general population participants (15
). Further models from the study-wide analysis also suggested maternal smoking and abstaining from alcohol during pregnancy, reducing their work hours or not working at all during pregnancy, and those who underestimated their child’s risk for T1D as predictors of early withdrawal (16). It was not practical to include all of these factors in this analysis because of the site specific sample size and there was only two years of enrollment being examined in our eighteen-month withdrawal assessment.
The Colorado-specific analysis reported here included an evaluation of maternal age and gender as well as the evaluation of the video and ethnicity/race. This analysis confirms the finding that younger mothers are significantly more likely to withdrawal. Ethnicity/race was particularly important for the Colorado site to evaluate because of the Hispanic representation, both Spanish-speaking preferred and English-speaking, at our site. Although the Spanish-speaking participants were not included in this analysis because the video was not produced in Spanish, an unpublished analysis has examined Spanish-speaking Hispanics compared to English-speaking Hispanics and has found a significant association with early withdrawal.
Strengths of the present study are that this was a naturally occurring comparison of one group who received an intervention and another that did not, without any misclassification of group assignment. All participants were eligible for the follow-up study and the outcomes of enrollment and retention are measurable, real outcomes rather than those of a hypothetical situation. Furthermore, the composition of the two comparison groups was similar and there was sufficient sample size to detect differences.
We hypothesized that the quality of the professionally executed video enhanced our ability to present the study protocol in a more accessible, visual and personalized format while explaining the study requirements in such a way that participants could make an informed decision to participate. Although we have demonstrated that those receiving the video benefited in this way, resulting in higher enrollment, we have no direct measures of the mechanisms of this effect. Participants receiving the video were not consistently asked whether they viewed the video and we had no measures of whether the understanding of the study protocol was better in those receiving the video compared to those who did not. Other factors that were potentially different between the two groups included staff turn-over and variation in administering the enrollment protocol over time. It was difficult to assess how these factors might have affected enrollment. However, the impact of these factors on the outcome is possibly minimized because all staff received standardized training in administration of the enrollment protocol that included standardized scripts, role playing and observation. Furthermore, the same experienced enrollment staff persons were involved over this two year time period and the number of new staff members added to this task was about the same in each year.
In longitudinal study designs, enrolling and retaining a representative cohort is essential to the generalizability of study findings. As forms of communication evolve and adapt to the available technological environment, methods of communicating essential information to study participants at enrollment and beyond must also evolve. Methods which aid in clearly describing study protocols to potential participants enable better informed decisions. A realistic and informed decision might enhance long term participation
Key factors for enhancing prospective study retention include developing and sustaining solid relationships between the participant and study staff. The strength of this relationship is based on communication. Communication strategies need to effectively reach participants through modes that are routine and familiar to a new generation of study participants, such as the use of video YouTube clips, websites, and various forms of social media that are used regularly by these participants. As a new generation of participants are being asked to participate in long-term research, such as in the TEDDY Study, it is important to think about how study designs can adapt using these innovations for the benefit of both participant and study validity.