Trends in Diagnostic Testing Practices for ASD in a Population-Based Sample from Philadelphia County

Background: Trends in the use of diagnostic evaluation tools are not well described, especially in high density urban areas where minority populations are typically large.  Data collected for the Pennsylvania Autism and Developmental Disabilities Surveillance Program (PADDSP) of the ADDM Network will be analyzed to characterize the use of diagnostic and/or screening tests among cases of ASD in Philadelphia County over two study years, 2002 and 2006.  In 2002 a total of 111 eight-year-old children were identified to meet the DSM-IV-TR (APA, 2000) criteria for the ASDs. The calculated prevalence was 5.3 per 1,000 8 year olds. The prevalence of ASD among 8-year olds in Philadelphia County in 2006 will be reported in February 2009.
Objectives: The purpose of the presentation is to describe, (1) the proportion of cases who received an ASD diagnostic evaluation stratified by sex and race/ethnicity for each surveillance year (2002 and 2006), (2) the distribution of ASD test type by sex and race for each surveillance year (2002 and 2006), (3) changes over time in the use of diagnostic test instruments among cases who had a previous ASD diagnostic evaluation; (4) changes over time in the distribution of provider specialty administering ASD diagnostic evaluation.
Methods: Data will include the reports of the specific ASD diagnostic tests used for children in Philadelphia County as recorded in the PADDSP database. These include: the Autism Behavior Checklist (ABC), the Autism Diagnostic Interview-Revised (ADI-R), the Autism Diagnostic Observation Schedule (ADOS), the Childhood Autism Rating Scale (CARS), the Gilliam Autism Rating Scale (GARS), the Gilliam Asperger’s Disorder Scale (GADS), or other ASD Test. We will use data from the PADDSP site, only, for study years 2002 and 2006. Data will be analyzed descriptively using frequencies, proportions, etc.
Results: (Preliminary, 2002 SY ONLY)
Of 111 cases, 28 (25%) mentioned an ASD test in the child’s records. The most commonly used ASD evaluation was the CARS followed by GARS and Other. ADOS and ADI-R were used rarely (4% of cases).There is no difference in the kind of evaluations used for non-white and whites or males and females. White males and non-white females were evaluated at an average age of 59 mo. AA males were 1^st evaluated at the oldest age (76mo). Evaluations were conducted by psychologists (49%), developmental pediatricians (29%), other or unknown (16%), and an educator (6%).A child’s first ASD evaluation was most often performed by a psychologist (51%) at an average age of 69 mo. 28% of first evaluations were conducted by a developmental pediatrician at an average age of 74 mo.

Conclusions: Pending analysis of data from the 2006 Study Year. We will compare our findings to the report of the use of tests in four other Surveillance states in which there was a steady increase in the proportion of children evaluated using one or more ASD diagnostic tests.