title: Frequency and pattern of documented diagnostic features and the age of autism identification.
abstract: OBJECTIVE
  The DSM-IV-TR specifies 12 behavioral features that can occur in hundreds of possible combinations to meet diagnostic criteria for autism spectrum disorder (ASD). This paper describes the frequency and variability with which the 12 behavioral features are documented in a population-based cohort of 8-year-old children under surveillance for ASD, and examines whether documentation of certain features, alone or in combination with other features, is associated with earlier age of community identification of ASD.
  
  
  METHODS
  Statistical analysis of behavioral features documented for a population-based sample of 2,757 children, 8 years old, with ASD in 11 geographically-defined areas in the US participating in the Autism and Developmental Disabilities Monitoring Network in 2006.
  
  
  RESULTS
  The median age at ASD identification was inversely associated with the number of documented behavioral features, decreasing from 8.2 years for children with only seven behavioral features to 3.8 years for children with all 12. Documented impairments in nonverbal communication, pretend play, inflexible routines, and repetitive motor behaviors were associated with earlier identification, whereas impairments in peer relations, conversational ability, and idiosyncratic speech were associated with later identification.
  
  
  CONCLUSIONS
  The age dependence of some of the behavioral features leading to an autism diagnosis, as well as the inverse association between age at identification and number of behavioral features documented, have implications for efforts to improve early identification. Progress in achieving early identification and provision of services for children with autism may be limited for those with fewer ASD behavioral features, as well as features likely to be detected at later ages.
authors.affiliation: University of Wisconsin-Madison, USA. mjmaenner@wisc.edu
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Maenner
authors.forename: Laura A
authors.initials: LA
authors.lastname: Schieve
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Rice
authors.forename: Christopher
authors.initials: C
authors.lastname: Cunniff
authors.forename: Ellen
authors.initials: E
authors.lastname: Giarelli
authors.forename: Russell S
authors.initials: RS
authors.lastname: Kirby
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Lee
authors.forename: Joyce S
authors.initials: JS
authors.lastname: Nicholas
authors.forename: Martha S
authors.initials: MS
authors.lastname: Wingate
authors.forename: Maureen S
authors.initials: MS
authors.lastname: Durkin
mesh_terms: D000367:Age Factors; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D006801:Humans; D008403:Mass Screening; D011159:Population Surveillance; D014481:United States / Q000453:epidemiology