Trajectory Research in Children with an Autism Diagnosis: A Scoping Review

Researchers increasingly employ longitudinal trajectory methods to understand developmental pathways of people on the autism spectrum across the lifespan. By assessing developmental or health-related outcome domains at three or more timepoints, trajectory studies can characterize their shape and varying rates of change over time. The purpose of this scoping review was to identify and summarize the published breadth of research that uses a trajectory study design to examine development in children (to age 18 years) diagnosed with autism. Using a systematic search and screening procedure, 103 studies were included. This review summarizes methodological characteristics across studies including the varying statistical approaches used. A series of figures maps where published research is available across 10 outcome domains and the ages over which children have been followed. Evidence gaps, informed by the perspectives of the autistic and caregiver stakeholders that were engaged in this review, are discussed. We recommend that future trajectory research addresses the absence of studies from low- and middle-income countries, considers longitudinal assessment of outcome domains that caregivers and autistic people consider meaningful, and plans follow-up periods with assessment timepoints that cover the gaps in ages where more outcome-specific data are needed.