A-TAC screening questionnaire
The A-TAC (Autism-Tics, ADHD and other Comorbidities) is a telephone interview developed by Christopher Gillberg and his group.
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About A-TAC
The A-TAC (Autism-Tics, ADHD and other Comorbidities) is a telephone interview developed by Christopher Gillberg and his group at Gothenburg University for use in the CATSS (Child and Adolescent Twin Study in Sweden). It can be used by non-child-psychiatrists. It provides good proxies for several ESSENCE diagnostic categories (including autism, ADHD, DCD, and learning disability), but cannot be used as a stand-alone diagnostic instrument. There have been many studies published reporting results from the CATSS using A-TAC and also a number of clinical validation studies, including the original publication in the British Journal of Psychiatry (Hansson et al, 2006). Cut-offs for various diagnostic category proxies can be found in these publications.
How is the A-TAC calculated?
The A-TAC consists of a number of modules which, either individually or cumulatively, indicate a potential screening diagnosis. The A-TAC has seen a few changes over the years, but the gate questions form the basis of the validations. The gate questions are the questions above the black line in each module. For example, question 1 for module A and questions 7-15 in module C. The questions below the gate (those that start with a letter) are of clinical interest but do not add anything in terms of the statistical prediction of a diagnosis. Modules C and D constitute ADHD and modules H, I and J constitute autism. If a person answers “No”, this is scored as 0, “Yes, to some extent” is scored as 0.5 and “Yes” is scored as 1.
How is the A-TAC validated?
The validations are based on A-TAC-interviews where laymen (in one case psychology students) have asked parents the questions verbatim over the phone, after which the concordance has been calculated through clinical studies or registry follow-ups. Note that the validations are primarily based on A-TAC interviews with parents whose children were either nine or twelve years old, and always over the phone. The A-TAC has not only been validated in Sweden; a Spanish research group has also carried out an external validation of the autism module. Links to the validation studies are included below.
Are there cut-offs?
Different conditions have different cut-offs. The table below shows that autism, ADHD, learning difficulties and developmental coordination disorder have both a high and a low cut-off, depending on which level of sensitivity and specificity one wishes to apply. Note that these are based on the gate questions (see above), where each question is scored as 0 for “No”, 0.5 for “Yes, to some extent” and 1 for “Yes”. The cut-offs only serve as indications but can provide an overview of the individual’s constellations of problems.
| Condition | Cut-off |
|---|---|
| Autism | 4,5 (low), 8,5 (high) |
| ADHD | 6 (low), 12,5 (high) |
| Learning difficulties | 1 (low), 3 (high) |
| Developmental coordination disorder | 0.5 (low), 1 (high) |
| Tic disorder | 1,5 |
| Oppositional defiant disorder | 3 |
| Conduct disorder | 2 |
| Obsessive-compulsive disorder | 1 |
| Eating disorder | 1 |
