title: Implications for estimates of disability in children: a comparison of definitional components.
abstract: OBJECTIVE
  To test how prevalence estimates and characteristics of children vary by the way that disability is defined. Specifically, to determine 1) the proportions of children identified as disabled by one particular operationalization of disability based on parental reports of three types of consequences (i.e., functional limitations [FL]), dependence on compensatory mechanisms (CD), and service use or need beyond routine [SU/N]), and 2) whether children identified as disabled by these three types of consequences differ by type of disorder or condition, age, socioeconomic status, or race.
  
  
  METHODS
  We analyzed a national dataset representing a random sample of 712 households with 1388 children. The Questionnaire for Identifying Children with Chronic Conditions (QuICCC) was used to identify children with disabling conditions. We divided the QuICCC items into three discrete sets, reflecting three definitional components of disability, and compared the proportions and characteristics of children fitting these components separately and in combination.
  
  
  RESULTS
  Using the QuICCC definition of disability, SU/N identified the largest proportion of children (72%), followed by CD (55%) and FLs (49%). Forty-four percent of children were identified by only one component, 36% by two components in any combination, and 20% by all three components. The type of disorder or condition generally did not vary by the three definitional components, although the FL component may be more effective at identifying children with sensory impairments. Children identified by two or more components were more likely to have multiple conditions and had more pervasive disorders than those identified by only one component. The youngest children (0 to 3 years old) may be less likely to be identified as disabled than children of other ages, especially by FLs. FLs also were more likely to identify children from the poorest and least educated families.
  
  
  CONCLUSIONS
  Although the specific findings reported here pertain to a single definitional approach (the QuICCC), the data highlight that who will be classified as disabled (and who will not) may be dependent on how disability is defined. The implications of using different definitions and definitional components on both the prevalence and the characteristics of children with disabilities need to be considered before data can be applied responsibly and appropriately.
authors.affiliation: Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: L E
authors.initials: LE
authors.lastname: Westbrook
authors.forename: E J
authors.initials: EJ
authors.lastname: Silver
authors.forename: R E
authors.initials: RE
authors.lastname: Stein
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease / Q000145:classification* / Q000453:epidemiology; D019988:Children with Disabilities / Q000145:classification* / Q000706:statistics & numerical data; D005260:Female; D006306:Health Surveys; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D044469:Racial Groups; D011897:Random Allocation; D012737:Sex Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology