Predicting the diagnosis of autism in adults using the Autism-Spectrum Quotient (AQ) questionnaire

K. L. Ashwood, N. Gillan, J. Horder, Hannah Hayward, E. Woodhouse, F. S. Mcewen, J. Findon, H. Eklund, D. Spain, C. E. Wilson, T. Cadman, Susan Young, V. Stoencheva, Clodagh Murphy, Dene Robertson, T. Charman, Philip Bolton, K. Glaser, P. Asherson, E. SimonoffD. G. Murphy

Research output: Contribution to journalArticle (Academic Journal)peer-review

65 Citations (Scopus)
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Abstract

Background

Many adults with autism spectrum disorder (ASD) remain undiagnosed. Specialist assessment clinics enable the detection of these cases, but such services are often overstretched. It has been proposed that unnecessary referrals to these services could be reduced by prioritizing individuals who score highly on the Autism-Spectrum Quotient (AQ), a self-report questionnaire measure of autistic traits. However, the ability of the AQ to predict who will go on to receive a diagnosis of ASD in adults is unclear.

Method

We studied 476 adults, seen consecutively at a national ASD diagnostic referral service for suspected ASD. We tested AQ scores as predictors of ASD diagnosis made by expert clinicians according to International Classification of Diseases (ICD)-10 criteria, informed by the Autism Diagnostic Observation Schedule-Generic (ADOS-G) and Autism Diagnostic Interview-Revised (ADI-R) assessments.

Results

Of the participants, 73% received a clinical diagnosis of ASD. Self-report AQ scores did not significantly predict receipt of a diagnosis. While AQ scores provided high sensitivity of 0.77 [95% confidence interval (CI) 0.72–0.82] and positive predictive value of 0.76 (95% CI 0.70–0.80), the specificity of 0.29 (95% CI 0.20–0.38) and negative predictive value of 0.36 (95% CI 0.22–0.40) were low. Thus, 64% of those who scored below the AQ cut-off were ‘false negatives’ who did in fact have ASD. Co-morbidity data revealed that generalized anxiety disorder may ‘mimic’ ASD and inflate AQ scores, leading to false positives.

Conclusions

The AQ's utility for screening referrals was limited in this sample. Recommendations supporting the AQ's role in the assessment of adult ASD, e.g. UK NICE guidelines, may need to be reconsidered.
Original languageEnglish
Pages (from-to)2595-2604
Number of pages10
JournalPsychological Medicine
Volume46
Issue number12
Early online date29 Jun 2016
DOIs
Publication statusPublished - 1 Sep 2016

Keywords

  • Autism
  • autism spectrum disorders
  • neurodevelopmental disorders
  • screening
  • self-report

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