Methods and Challenges in a Cohort Study of Infants and Toddlers With Craniofacial Microsomia: The Clock Study

Objective: The Craniofacial microsomia: Longitudinal Outcomes in Children pre-Kindergarten (CLOCK) study is a longitudinal cohort study of neurobehavioral outcomes in infants and toddlers with craniofacial microsomia (CFM). In this article, we review the data collection and methods used to characterize this complex condition and describe the demographic and clinical characteristics of the cohort. Setting: Craniofacial and otolaryngology clinics at 5 study sites. Participants: Infants with CFM and unaffected infants (controls) ages 12 to 24 months were recruited from the same geographical regions and followed to age 36 to 48 months. Methods: Phenotypic, neurodevelopmental, and facial expression assessments were completed during the first and third waves of data collection (time 1 and time 3, respectively). Medical history data were taken at both of these time points and during an intermediate parent phone interview (time 2). Results: Our cohort includes 108 cases and 84 controls. Most cases and controls identified as white and 55% of cases and 37% of controls identified as Hispanic. Nearly all cases had microtia (95%) and 59% had mandibular hypoplasia. Cases received extensive clinical care in infancy, with 59% receiving care in a craniofacial clinic and 28% experiencing at least one surgery. Study visits were completed at a study site (92%) or at the participant's home (8%). Conclusions: The CLOCK study represents an effort to overcome the challenges of characterizing the phenotypic and neurodevelopmental outcomes of CFM in a large, demographically and geographically diverse cohort.