Concept: Autism Spectrum Disorder (ASD) - Measuring Treatment Prevalence

Introduction

This concept identifies data sources and diagnostic codes used to identify cases of Autism Spectrum Disorder (ASD) in research conducted by the Manitoba Centre for Health Policy (MCHP). This information can be used to estimate the prevalence of treatment for ASD.

Definition of Autism Spectrum Disorder

ASD is a pervasive developmental disorder that typically affects a person's social interactions and ability to communicate, and may be evident by repetitive behaviours or a strong attachment to a routine. The severity ranges from mild to severe and it includes diagnoses of Autistic Disorder, Pervasive Developmental Disorder-Not Otherwise Specified, and Asperger's Disorder ( Autism Society Canada, 2005 ).

Methods

Multiple data sources in the Manitoba Population Research Data Repository at MCHP can be used to identify cases of ASD and estimate the prevalence of its treatment. In Brownell et al. (2008), children with ASD were identified using diagnoses on hospital and physician records and information from education records on special school funding received for students with ASD. An individual was considered to have ASD if he/she had at least one of the following:


• one or more hospitalizations with any one of the recorded ICD-9-CM diagnostic codes as 299.0, 299.1, 299.8, or 299.9, or any one of the recorded ICD-10-CA diagnostic codes as F84.0-F84.5, F84.8, or F84.9
  
  
• one or more physician claims with the diagnosis code 299
  
  
• identified as "ASD" within the variable CATEORGYN of the Manitoba Education Special Needs data file. (Children with ASD were previously identified by the code "AUT" in this variable within the education data.)

The Manitoba Education Special Needs data also contains a variable, STATUSN, that identifies whether the funding is approved, denied, non-supportable or terminated, and works in conjunction with CATEGORYN . Only those with an "approved status" are included in the selection process.

Please see Autism Spectrum ICD Codes.pdf for a description of ICD-9-CM and ICD-10-CA diagnoses codes used to identify ASD in the Child Health Atlas Update (2008).

In The Mental Health of Manitoba's Children deliverable by Chartier et al., (2016), they used the same definition as Brownell et al. (2008), except the hospital data only included ICD-10-CA codes because of the time period of the study.

Cautions

• When using multiple data sources, there is a risk that individuals may appear in more than one data set, and depending on the purpose of the study, methods must be used to ensure that these cases are only counted once.
  
  
• A child with ASD may not be included in these data sources if the child is undiagnosed (or untreated), diagnosed in a setting other than the hospital or by a physician, or not approved for educational funding (Brownell et al., 2008). Brownell et al. (2008) cautions that this definition should be "considered a measure of treatment prevalence" (p.217).