| Introduction: The diagnosis of autism is often delayed, which translates into a missed opportunity to provide treatment during a critical developmental period. The aims of this dissertation were: (1) to review studies that examined age at autism spectrum disorder (ASD) diagnosis, (2) to assess the relationship between state Medicaid program characteristics and other factors and children's compliance with American Academy of Pediatrics' (AAP) guidelines for well-child care prior to autistic disorder (AD) diagnosis, and (3) to examine the influence of compliance and state adoption of AAP schedule guidelines on age at diagnosis.;Methods: A review of studies published between 1990 and 2011 that examined factors associated with age at ASD diagnosis was conducted for Aim 1. Data from a national sample of Medicaid-enrolled, preschool-aged children were used to estimate the associations between Medicaid program characteristics and well-child care compliance and among well-child care compliance, state adoption of AAP schedule guidelines and age at AD diagnosis for Aims 2 and 3, respectively.;Findings: The 37 studies identified through the systematic review revealed factors at the child-, family- and community-levels that influenced age at diagnosis. Findings from the quantitative analyses indicated that greater state Medicaid program generosity, such as greater spending per child enrollee, and greater child-level need, as indicated by greater health service use and clinical diagnoses, were associated with higher well-child care compliance. Higher well-child care compliance from birth to diagnosis and receiving a greater number of visits in the first year of life were associated with earlier diagnosis. There was no association between state adoption of AAP schedule guidelines and age at diagnosis.;Conclusion: While some state-level factors play a role in influencing children's well-child care compliance, state adoption of AAP schedule guidelines did not influence age at diagnosis in this sample. However, higher child-level compliance was associated with earlier detection, supporting current AAP guidelines with respect to the timing and frequency of well-child care for preschool-age children. The potential benefit of timely well-child care, as it relates to the early detection of AD, should be communicated to the pediatric practice community and highlighted during clinicians' interactions with parents. |
