The four ASD assessments
An explanation of the four different assessments for autism present in the latest 3di software.
Background
Within the 3di's autism provision, there are four different assessments:
ICD-10 ASD extended
ICD-10 ASD brief
DSM-5 ASD extended
DSM-5 ASD brief
Each ASD assessment has a corresponding set of questions (known as a route), a scoring algorithm, and a set of scoring tables in the Word reports. The assessments were added to the software over years of research and use. We have always maintained the capability to run the older assessments.
The 3di has a bank of nearly 900 questions. Each ASD assessment uses a different and much smaller subset of questions drawn from this bank. Every last question in the question bank is listed in the Interview Explorer, and during an interview you can view and answer any question at any time. However in typical usage, you will choose a single assessment and answer only the much smaller set of questions from its route.
Recall from Key concepts that a report can be generated at any stage of completion of the 3di's questions. The structure of the full report is always the same and will be filled in as completely as possible based on the questions you have answered. In the latest 3di versions, there are therefore up to four sets of report tables, corresponding to each of the four assessments.
In normal clinical use, picking the appropriate ASD route in the Route Explorer will allow you to complete just the necessary questions for that single assessment, thus populating the corresponding report components.
If you generate a report without answering any questions, the result will be structurally complete but clinically uninformative — containing only placeholder notes explaining why scores could not be calculated. For clinical validity, you should aim to complete all questions on the route relevant to your chosen assessment.
It is possible but nowadays unusual to fill in sufficient questions to complete more than one assessment. Formerly, the 3di contained a combined route which covered both the ICD-10 brief and DSM-5 extended assessments, which might further be supplemented by completing a question set for a related non-ASD disorder.
For details on the structure and content of the report documents, see Reports.
The ASD assessments today
The ASD routes contain only those questions which contribute to the scoring tables in the report. They do not contain the qualitative questions about the child's family, medical and educational history. For a richer report, you can complete these in advance using pre-entry, or during the interview via the Interview Explorer.
1. ICD-10 extended
This was the first ASD algorithm implemented in the 3di, around 2004. Its scoring is based on 134 questions. The corresponding route is ASD_extended (ICD-10).
This original 3di assessment was published in The developmental, dimensional and diagnostic interview (3di): a novel computerized assessment for autism spectrum disorders.
In recent 3di versions, if you still want to see ICD-10 report components you need to visit the Preferences form. This output of this algorithm appears only in the extended Word report, and not in the brief Word report. In the extended Word report the corresponding tables appear under the heading ICD-10 ASD.
2. ICD-10 brief
This was the second ASD algorithm implemented in the 3di, around 2009. Its scoring is based on 61 questions. The corresponding route is ASD_brief (ICD-10).
The derivation and validation of this assessment was published in The construction and validation of a short form of the developmental, diagnostic and dimensional interview.
In recent 3di versions, if you still want to see ICD-10 report components you need to visit the Preferences form. This output of this algorithm appears only in the brief Word report, and not in the extended Word report. In the brief Word report the corresponding sections appear under the heading ICD-10 ASD.
3. DSM-5 extended
This was the third ASD algorithm implemented in the 3di, around 2013. Its scoring is based on 177 questions. The corresponding route is ASD_extended (DSM-5 Crit A + B).
This output of this algorithm appears only in the extended Word report, and not in the brief Word report, under the heading DSM-5: ASD extended assessment.
4. DSM-5 brief
This was the fourth ASD algorithm implemented in the 3di, in 2022. Its scoring is based on 66 questions. The corresponding route for this algorithm is named ASD_brief (DSM-5 Crit A+B).
This output of this algorithm, despite having 'brief' in the name, appears in both the brief and extended Word reports, under the heading DSM-5: ASD brief assessment.
Details of the scoring algorithms
Details of the algorithms 1 and 2 and our amalgamation of ICD-10 and DSM-4 are explained in three files found in the 3di installation folder under the Reference subfolder. ASD_three-domain_scales_defined and ASD_diagnosis_flowcharts_3_domain describe the algorithm and how a diagnostic outcome is arrived at, while ASD_scales_Ref details which individual questions contribute to each subscale.
Details of the DSM-5 algorithms 3 and 4 are explained in two files found in the 3di installation folder under the Reference subfolder. DSM-5_ASD_scoring describes the algorithm, while ASD_scales_Ref details which individual questions contribute to each subscale.
3di-adult
You may have heard about this assessment. The 3di-adult was a standalone, pen-and-paper tool developed as part of a research project which drew on the 3di question bank but was never implemented in the software, and presently there are no plans to do so. You can read the paper here.
The 3di software is currently not suitable for the assessment of adults.
Origin of the assessments
The 3di was initially developed as a research tool starting around the year 1998 at the Great Ormond Street Institute of Child Health under the direction of Professor David Skuse. The World Health Organisation's International Statistical Classification of Diseases and Related Health Problems, 10th revision, or ICD-10, came into effect on 1 Jan 1993. Meanwhile the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, fourth edition, or DSM-IV, was published in 1994. The 3di treated the two systems as broadly equivalent, and the 3di's first ASD assessment was built around an amalgamation of ICD-10 and DSM-IV criteria.
The first autism assessment in the 3di, now known as the ICD-10 extended, contained 134 questions, and was designed for research use where there was sufficient time for such a thorough assessment.
Over the following years, demand grew for a quicker autism informant interview for use in CAMHS clinics where there was less time available. This led to the development of the ICD-10 brief assessment.
DSM-5 came into effect in 2013, followed by ICD-11 on 1 Jan 2022. The 3di was updated with a new DSM-5 extended assessment for autism in 2013. Finally in late 2022 the DSM-5 brief assessment was released.
Comparing DSM-5 and ICD-11, we consider that by design the two sets of criteria are so similar that ASD outcomes (and many others) can be reported as DSM-5 or as ICD-11. The 3di always references DSM-5 because the APA got there many years before the WHO; you can substitute one term for the other in your reports or perhaps reference neither.
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