Concept: Intellectual Disability (ID) (Mental Retardation) / Developmental Disability (DD) / Developmental Disorders / Intellectual or Developmental Disability (IDD)

Introduction

This concept briefly describes the conditions of intellectual disability (mental retardation) / developmental disability / developmental disorders, and provides operational definitions used in research that utilizes the Manitoba Centre for Health Policy (MCHP) data repository. Intellectual Disability (ID), Developmental Disability (DD), Developmental Disorders (DD), and Intellectual or Developmental Disability (IDD) are all terms that have been used used to describe a specific group of medical conditions over time. These conditions are usually detected in the early stage of childhood, and persist throughout life.

Definitions and Additional Information

The Canadian National Coalition on Dual Diagnosis (2008) Dual Diagnosis Glossary, defines intellectual disability as:


"... people with cognitive deficits who may or may not have other developmental disabilities. It is a term often used synonymously with developmental disability. Both intellectual disability and developmental disability were developed to counteract the stigmatization attached to mental retardation. However, the DSM-IV TR [Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision] continues to use 'mental retardation'. (Source: The American Association of Intellectual and Developmental Disability)".

The Dual Diagnosis Glossary also contains the following "adopted" definition for developmental disability:

"Children, youth and adults who have significantly greater difficulty than most people with intellectual and adaptive functioning and have had such difficulties from a very early age (or the developmental period prior to age 18). 'Adaptive functioning' means carrying out everyday activities such as communicating and interacting with others, managing money, doing household activities and attending to personal care.

This definition of developmental disability also includes children, youth and adults with developmental disorders such as Fetal Alcohol Spectrum Disorders or Autism Spectrum Disorders."

For more information describing intellectual and developmental disabilities, visit:


• the Canadian Association for Research and Education in Intellectual Disabilities (CARE-ID) website;
  
• National Dissemination Center for Children with Disabilities (NICHCY) Disability Fact Sheet #8 (2009), and;
  
• the American Association of Intellectual and Developmental Disability (AAIDD) website.
  
  NOTE: AAIDD is considered to be the most authoritative source on intellectual disability (Balogh, 2010).

Overtime, the medical conditions used to identify these types of development disabilities in research have varied, and the name used to describe these conditions has varied. "Developmental disorders are characterized by significant impediments in intellectual and adaptive functioning from a very early age. The definition of developmental disorders includes disorders such as mental retardation, chromosomal anomalies (including Down's, Patau's and Edward's syndromes), Fetal Alcohol Spectrum Disorders (FASD), and Autism Spectrum Disorders (ASD)". (Chartier et al., 2016). In more recent MCHP research, Brownell et al. 2020, the term intellectual or developmental disability (IDD) is used to describe this broad spectrum of medical conditions.

1 - Identification of Intellectual Disability (ID)

This section describes research methods using data in the MCHP Data Repository to identify cases of intellectual disability (ID). For some studies, the focus is on individuals with an ID, while for other studies, the researcher may want to exclude individuals with ID or use ID as a predictor variable in regression models.

Data Sources and Selection of ID cases

In Balogh (2010) and Ouellette-Kuntz et al. (2010), a variety of data sources were used to select individuals with ID. This approach involves the use of four different data sources available from the MCHP Data Repository:


1. Education Data
   
   In the Manitoba Education & Youth (MEY) Special Needs data file, children receiving special (categorical) funding for special needs were identified using the variable CATEGORYN. Children with mental retardation or ID were identified by a value of "Multiple Handicaps" ("MH") in this variable.
   
   The 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.
   
   NOTE: The special needs education data also allows us to determine cases of Autism Spectrum Disorders (ASD). However, not all cases of ASD will also have an intellectual disability. Therefore, a decision must be made whether to include the values of ASD in the definition of ID. Including children with ASD will overestimate the rate of ID, as only approximately half of those with ASD may have an ID (Fombonne, 2005).
   
   
2. Employment and Income Assistance Data
   
   In the Social Allowances Management Information Network (SAMIN) data, individuals with a reason for receipt of income assistance equal to "mental retardation" were selected as ID cases.
   
   
3. Hospital Abstracts Data
   
   In the Hospital Abstracts data, individuals with at least one of the following diagnosis codes in any of the diagnosis fields were selected as ID cases (NOTE: In Manitoba, for data up to March 31, 2004, up to 16 diagnoses can be coded in an abstract using ICD-9-CM):
   
   
   • 317 = Mild Mental Retardation (MR)
     
   • 318 = Other MR
     
   • 319 = Unspecified MR
     
   • 758.0 - 758.3 = Chromosomal Anomalies (includes Down's, Patau's and Edward's syndromes)
     
   • 759.81 - 759.89 = Other and unspecified congenital anomalies (includes Fragile x and Prader-willi syndromes)
   
   NOTE: Ouellette-Kuntz et al. (2010) also included ICD-9-CM code 760 (Fetal Alcohol Syndrome (FAS)) in selecting cases of ID from the hospital data. However, as with ASDs, not all children with FAS also have an ID. In Nulman et al. (2007), they reported that only 19% of persons with FAS also have an ID. Again, a research decision must be made whether to include FAS cases in the definition of ID.
   
   
4. Medical Services Data
   
   In the Medical Services data, diagnoses are recorded using 3-digit ICD-9-CM diagnosis codes, and therefore the 5-digit, specific codes used in the hospital data are not available from the Medical Services data. Note: In December 2018, a 5-digit diagnosis code variable was added to the Medical Services data. If recorded, the first 3-digits of both the 3-digit and 5-digit diagnosis code variables will match exactly. The 5-digit diagnosis code variable applies to records from 2015/16 forward.
   
   The following 3-digit ICD-9-CM codes were used to select cases of ID from the Medical Services data:
   
   
   • 317 = Mild Mental Retardation (MR)
     
   • 318 = Other MR
     
   • 319 = Unspecified MR
   
   NOTE: The three-digit ICD codes 758 and 759 from the Medical Services data were also investigated. However, because they contain additional diagnoses not associated with ID and DD (such as Kleinfelter's, sex chromosome anomalies, and anomalies of the spleen and adrenal glands), they were not included in the list of identifying codes from the Medical Services data.

Exclusion of Intellectual Disability Cases

In What is Most Important: Social Factors, Health Selection, and Adolescent Educational Achievement, (2013), Roos et al. excluded cases of ID in their analysis. In this study, ID was defined as anyone up to age 14 diagnosed with ID, selected using the following method:


• within the hospital abstracts and medical services data using the ICD-9-CM codes listed above. Additional exclusions in this study included anyone diagnosed with "autism and other psychoses with origin specific to childhood": ICD-9-CM code = 299; and/or
  
• within the Education data with special needs identified by "multiple handicaps" (MH), "autism" (AUT), or "Autism Spectrum Disorder (ASD)";
  
  NOTE: The "autism" (AUT) code is no longer used in the Education data.

Due to the time frame of this study, the abstract data also contained diagnoses coded using ICD-10-CA. (NOTE: In Manitoba, for data beginning April 1, 2004, up to 25 diagnoses can be recorded in the abstract using ICD-10-CA codes). The following ICD-10-CA codes were used to select and exclude ID cases:


• F70 = Mild mental retardation
  
• F71 = Moderate mental retardation
  
• F72 = Severe mental retardation
  
• F73 = Profound mental retardation
  
• F78 = Other mental retardation
  
• F79 = Unspecified mental retardation
  
• F84 = Pervasive developmental disorders

SAS Code for Intellectual Disability

An example SAS code program for identifying intellectual disability cases is available from the SAS code and formats section below - internal access only.

2 - Identification of Developmental Disability (DD)

There are different methods that have been used to identify developmental disabilities using data from the MCHP Data Repository. These are listed below.

1. Brownell et al. (2015) and Preliminary Research by Shooshtari et al.

In Brownell et al. (2015) and preliminary research by Shooshtari et al. - (unpublished), three different data sources are used to identify children with developmental disability (DD):


1. Enrollment, Marks and Assessments (STS/ICAB) Data - In the Manitoba Education & Youth (MEY) Special Needs data file, children receiving special (categorical) funding for special needs were identified using the variable CATEGORYN. Children with developmental disabilities are selected by a value of "Multiple Handicaps" ("MH") or "Autism Spectrum Disorder" (ASD) in this variable.
   
   The 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.
   
   For more information, please read the Special Needs Children - Method of Identification from Education Data concept.
   
   
2. Hospital Abstract Data
   
   In the Hospital Abstract data, individuals with at least one of the following ICD-9-CM diagnosis codes in any of the diagnosis fields were selected as DD cases. ( NOTE: In Manitoba, up to 16 diagnoses can be coded in a hospital abstract using ICD-9-CM):
   
   
   • 317 = Mild Mental Retardation (MR)
     
   • 318 = Other MR
     
   • 319 = Unspecified MR
     
   • 299 = Autism and other psychoses with origin specific to childhood
     
   • 758.0 - 758.3 = Chromosomal Anomalies (includes Down's, Patau's and Edward's syndromes)
     
   • 759.81 - 759.89 = Other and unspecified congenital anomalies (includes Fragile X and Prader-willi syndromes)
     
   • 760.71 = Fetal Alcohol Syndrome (FAS)
   
   The timeframe for this study involved a change in the ICD coding system in the Hospital Abstract data, and the following ICD-10-CA codes were used to select cases of Developmental Disability. ( NOTE: up to 25 diagnoses can be coded in a hospital abstract using ICD-10-CA):
   
   
   • F70.0, F70.1, F70.8, F70.9 = Mild mental retardation;
     
   • F71.0, F71.1, F71.8, F71.9 = Moderate mental retardation;
     
   • F72.0, F72.1, F72.8, F72.9 = Severe mental retardation;
     
   • F73.0, F73.1, F73.8, F73.9 = Profound mental retardation;
     
   • F78.0, F78.1, F78.8, F78.9 = Other mental retardation;
     
   • F79.0, F79.1, F79.8, F79.9 = Unspecified mental retardation;
     
   • F84.0, F84.1, F84.3, F84.4, F84.5, F84.8, F84.9 = Pervasive developmental disorders;
     
   • P04.3 = Fetus and newborn affected by maternal use of alcohol (this excludes fetal alcohol syndrome = Q86.0);
     
   • Q86.0, Q86.1, Q86.2, Q86.8 = Congenital malformation syndromes due to known exogenous causes, not elsewhere classified;
     
   • Q87.0, Q87.1, Q87.2, Q87.3, Q87.5, Q87.8 = Other specified congenital malformation syndromes affecting multiple systems;
     
   • Q89.8 = Other specified congenital malformations;
     
   • Q90.0, Q90.1, Q90.2, Q90.9 = Down's syndrome;
     
   • Q91.0, Q91.1, 91.2, Q91.3, 91.4, Q91.5, 91.6, Q91.7 = Edward's syndrome and Patau's syndrome;
     
   • Q93.0, Q93.1, Q93.2, Q93.3, Q93.4, Q93.5, Q93.6, Q93.7, Q93.8, Q93.9 = Monosomies and deletions from the autosomes, not elsewhere classified; and
     
   • Q99.2 = Fragile X chromosome
   
   
3. Medical Services / Physician Visit Data
   
   In the Medical Services (Physician Visit) data, diagnoses are recorded using 3-digit ICD-9-CM diagnosis codes, and therefore the 5-digit, specific codes used in the hospital data are not available from the Medical Services data. Note: In December 2018, a 5-digit diagnosis code variable was added to the Medical Services data. If recorded, the first 3-digits of both the 3-digit and 5-digit diagnosis code variables will match exactly. The 5-digit diagnosis code variable applies to records from 2015/16 forward.
   
   The following 3-digit ICD-9-CM codes were used to select cases of Developmental Disability from the Medical Services data:
   
   
   • 317 = Mild Mental Retardation (MR)
     
   • 318 = Other MR
     
   • 319 = Unspecified MR
     
   • 299 = Autism and other psychoses with origin specific to childhood

2. Shooshtari et al. (2011)

In Shooshtari et al. (2011), a variety of data sources are used to develop a case definition to identify adults with developmental disability (DD). This case definition "... included those meeting at least one of the following three criteria:


1. received income assistance for reasons of ID, from Manitoba Department of Family Services and Consumer Affairs;
   
   
2. received special education funding from Manitoba Department of Education for reasons of multiple handicaps, usually defined as ID plus one or more physical disabilities; and
   
   
3. had at least one ICD diagnostic code for ID and/or ASDs in either the physician claims [Medical Services] or the hospital abstracts database. The ICD diagnostic codes used in this study to identify cases with ID included 317 (mild mental retardation (MR)), 318 (moderate, severe, and profound MR), 319 (unspecified MR), 760 (fetal alcohol spectrum disorders (FASDs)), and 758 and 759 (chromosomal and congenital anomalies associated with MR, including Down’s syndrome, Patau’s and Edward syndromes, Fragile X syndrome, and Prader Willi syndrome). The ICD–10–CD that were used included F70.0–F70.1; F70.8–F71.1; F71.8–F72.1; F72.8–F73.1; F73.8–F73.9; F7.80–F78.1; F78.8–F79.1; F79.8–F79.9; F84.0–F84.1; F84.3–F84.5; F84.8–F84.9; P04.3; Q86.0–Q86.2; Q86.8; Q87.0–Q87.3; Q87.5; Q87.8; Q89.8; Q90.0–Q90.2; Q90.9–Q91.7; Q93.0–Q93.9; Q99.2"

For more information, please read the full text journal publication that is available from the Abstract link in the Shooshtari et al. (2011) reference below.

3. Chartier et al. (2015)

In the Care of Manitobans Living with Chronic Kidney Disease deliverable by Chartier et al. (2015) they investigated developmental disability as a comorbidity to chronic kidney disease (CKD) and end stage kidney disease (ESKD) for children aged 0 - 17 years old. They defined DD from the hospital abstracts data and the medical services (physician claims) data using the following ICD diagnosis codes and conditions. The diagnosis codes are described above in section 1 of Developmental Disabilities:


• one or more hospitalizations with diagnoses for intellectual disabilities, pervasive developmental disorders, Down's syndrome, autosomal deletion syndromes, Prader-Willi syndrome, other specified congenital anomalies, or FASD using:
  
  • ICD-9-CM codes: 317, 318, 319, 299, 758.0, 758.3, 759.81, 759.89, 760.71; OR
    
  • ICD-10-CA codes: : F70.0, F70.1, F70.8, F70.9, F71.0, F71.1, F71.8, F71.9, F72.0, F72.1, F72.8, F72.9, F73.0, F73.1, F73.8, F73.9, F78.0, F78.1, F78.8, F78.9, F79.0, F79.1, F79.8, F79.9, F84.0, F84.1, F84.3, F84.4, F84.5, F84.8, F84.9, P04.3, Q86.0, Q86.1, Q86.2, Q86.8, Q87.0, Q87.1, Q87.2, Q87.3, Q87.5, Q87.8, Q89.8, Q90.0, Q90.1, Q90.2, Q90.9, Q91.0, Q91.1, Q91.2, Q91.3, Q91.4, Q91.5, Q91.6, Q91.7, Q93.0, Q93.1, Q93.2, Q93.3, Q93.4, Q93.5, Q93.6, Q93.7, Q93.8, Q93.9, Q99.2; OR
  
  
• one or more physician claims with diagnoses for intellectual disabilities, pervasive developmental disorders:
  
  • ICD-9-CM codes: 317, 318, 319, 299

For more information on the prevalence and relative risk of developmental disabilities and chronic kidney disease, see:


• Table 5.2: Mental Disorders in Children.

3 - Identification of Developmental Disorders / Developmental Disability / Intellectual or Developmental Disability (IDD)

In the The Mental Health of Manitoba's Children deliverable by Chartier et al. (2016), The PAX Program in Manitoba: A Population-Based Analysis of Children's Outcomes by Brownell et al. (2018), The Overlap Between the Child Welfare and Youth Criminal Justice Systems: Documenting "Cross-Over Kids" by Brownell et al. (2020), and Our Children, Our Future: The Health and Well-being of First Nations Children in Manitoba by Chartier et al. (2020) they use four different data sources to define developmental disorders / developmental disability / intellectual or developmental disability (IDD) in children. In Chartier et al. (2016, 2020), this was restricted to children aged 0-19, in Brownell et al. (2018) this was restricted to children aged 3 years and older, and in Brownell et al. (2020) this was restricted to children aged 0-17. Brownell et al. (2020) also introduced the term intellectual or developmental disability (IDD).

The data sources and codes used to define developmental disorders (term used in Chartier et al. (2016) and Brownell et al. (2018)) / intellectual or developmental disability (term used in Brownell et al. (2020)) include:


1. Medical Services / Physician Visit Data
   
   The following 3-digit ICD-9-CM codes were used to select cases of developmental disorders / developmental disability from the Medical Services data:
   
   
   • 317 = Mild Mental Retardation (MR)
     
   • 318 = Other MR
     
   • 319 = Unspecified MR
     
   • 299 = Autism and other psychoses with origin specific to childhood
   
   
2. Hospital Abstracts Data
   
   The following ICD-10-CA codes were used to select cases of developmental disorders / developmental disability from the hospital data, including:
   
   
   • F70.0, F70.1, F70.8, F70.9 = Mild mental retardation;
     
   • F71.0, F71.1, F71.8, F71.9 = Moderate mental retardation;
     
   • F72.0, F72.1, F72.8, F72.9 = Severe mental retardation;
     
   • F73.0, F73.1, F73.8, F73.9 = Profound mental retardation;
     
   • F78.0, F78.1, F78.8, F78.9 = Other mental retardation;
     
   • F79.0, F79.1, F79.8, F79.9 = Unspecified mental retardation;
     
   • F84.0, F84.1, F84.3, F84.4, F84.5, F84.8, F84.9 = Pervasive developmental disorders;
     
   • P04.3 = Fetus and newborn affected by maternal use of alcohol (this excludes fetal alcohol syndrome = Q86.0)
     
   • Q86.0, Q86.1, Q86.2, Q86.8 = Congenital malformation syndromes due to known exogenous causes, not elsewhere classified;
     
   • Q87.0, Q87.1, Q87.2, Q87.3, Q87.5, Q87.8 = Other specified congenital malformation syndromes affecting multiple systems;
     
   • Q89.8 = Other specified congenital malformations;
     
   • Q90.0, Q90.1, Q90.2, Q90.9 = Down's syndrome;
     
   • Q91.0, Q91.1, 91.2, Q91.3, 91.4, Q91.5, 91.6, Q91.7 = Edward's syndrome and Patau's syndrome;
     
   • Q93.0, Q93.1, Q93.2, Q93.3, Q93.4, Q93.5, Q93.6, Q93.7, Q93.8, Q93.9 = Monosomies and deletions from the autosomes, not elsewhere classified; and
     
   • Q99.2 = Fragile X chromosome
     
     NOTE: In the definitions used in Chartier et al. (2016, 2020) and Brownell et al. (2020), two ICD-10-CA codes previously included were excluded:
     
     
     • P04.3 - "Fetus and newborn affected by maternal use of alcohol" presented unreliable coding; and
       
     • Q86.0 - fetal alcohol syndrome (dysmorphic) - this condition was determined using the Manitoba Fetal Alcohol Spectrum Disorder (FASD) data (see section #4 below).
   
   
3. Enrollment, Marks and Assessments (STS/ICAB) Data
   
   The Special Needs file in the education data is used to identify children receiving funding for special needs. Children with developmental disorders / developmental disability are identified by a value of "Multiple Handicaps" (MH) or "Autism Spectrum Disorder" (ASD) in the CATEGORYN variable.
   
   The 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.
   
   
4. Manitoba Fetal Alcohol Spectrum Disorder (FASD) Data
   
   Individuals identified as having developmental disorders / developmental disability are included if they had any of the following values in the DIA_Diagnosis variable:
   
   • "ARBD" - alcohol-related birth defects,
     
   • "ARND" - alcohol-related neurodevelopmental disorder,
     
   • "ARND/ARBD",
     
   • "FAS" - fetal alcohol syndrome,
     
   • "FAS/ARBD", or
     
   • "Partial FAS".

MCHP Research Findings

For more information on the MCHP research findings into Developmental Disorders / Developmental Disability / Intellectual or Developmental Disability, see:


• the section titled Developmental Disorders from The Mental Health of Manitoba's Children (2016) deliverable.
  
• the line with the heading "Child Diagnosed with a Developmental Disability (%)" from Table 4.1: Characteristics of all Grade 1 Students in Manitoba by Involvement in PAX RCT, 2011-12 from The PAX Program in Manitoba: A Population-Based Analysis of Children's Outcomes (2018) deliverable.
  
• the section titled Mental Disorders and Intellectual or Developmental Disabilities from The Overlap Between the Child Welfare and Youth Criminal Justice Systems: Documenting "Cross-Over Kids" (2020) deliverable.
  
• the section titled Developmental Disorders – including Autism from the Our Children, Our Future: The Health and Well-being of First Nations Children in Manitoba (2020) deliverable.

Cautions / Limitations

The following cautions / limitations apply to the identification of intellectual disability / developmental disability / developmental disorders:


• Although the use of the terms "mental retardation", "intellectual disability" and "developmental disability" are still prevalent, the term "developmental disorders" is being used more frequently in literature and covers a broader scope of medical conditions. Unfortunately, at this time, there is no standard definition using ICD or other coding systems that allow for a consistent method to define these conditions. In this situation, the choice of medical conditions that are used to define cases will have an impact on the over-/under-identification of cases in a study compared to other studies.
  
  
• The use of multiple data sources enhances the ability to identify a broader spectrum of disease/medical conditions in the population. One consideration when using multiple data sources is 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.
  
  
• Note the exclusion of two previously used ICD-10-CA codes from the hospital discharge data in the research by Chartier et al., (2016, 2020) and Brownell et al. (2020). One of these conditions, fetal alcohol syndrome (FAS), can now be identified using the Manitoba FASD data from 1999 forward.