Workflow and strategies for recruitment and retention in longitudinal 3D craniofacial imaging study

Longitudinal epidemiological studies are considered the gold standard for understanding craniofacial morphologic development, but participant recruitment and retention can be challenging. This study describes strategies used to recruit and maintain a high level of participation in a longitudinal study involving annual three-dimensional (3D) craniofacial soft-tissue imaging from healthy Taiwanese Chinese elementary school students aged 6 to 12 years. The key aspects for project delineation, implementation, and the initial three-year practical experiment are portrayed in an integrated multistep workflow: ethics-and grant-related issues; contact, approval, and engagement from partners of the project (school stakeholders and parents); a didactic approach to recruit the students; research staff composition with task design; three station-based data collection days with two educative activities (oral hygiene and psychosocial interaction stations) and one 3D craniofacial imaging activity; and reinforcement tactics to sustain the longitudinal annual participation after the first enrollment. Randomly selected students and teachers answered an experience satisfaction questionnaire (five-point Likert scale ranging from one to five) designed to assist in understanding what they think about the data collection day. Measures of frequency (percentage) and central tendency (mean) were adopted for descriptive analysis. Six of seven contacted schools accepted participation in the project. All parents who attended the explanatory meetings agreed to join the project. A cohort of 676 students (336 girls) participated at baseline enrollment, with a follow-up rate of 96% in the second data collection. The average questionnairerelated scores were 4.2 ± 0.7 and 4.4 ± 0.6 for teachers and students, respectively. These 3D craniofacial norms will benefit multidisciplinary teams managing cleft-craniofacial deformities in the globally distributed ethnic Chinese population, particularly useful for phenotypic variation characterization, conducting quantitative morphologic comparisons, and therapeutic planning and outcome assessment. The described pathway model will assist other groups to establish their own age-, sex-, and ethnic-specific normative databases.