Predictive validity of self-report questionnaires in the assessment of autism spectrum disorders in adults

Abstract

While various screening instruments for autism spectrum disorders are widely used in diagnostic assessments, their psychometric properties have not been simultaneously evaluated in the outpatient setting where these instruments are used most. In this study, we tested the Ritvo Autism Asperger Diagnostic Scale-Revised and two short versions of the Autism-Spectrum Quotient, the AQ-28 and AQ-10, in 210 patients referred for autism spectrum disorder assessment and in 63 controls. Of the 210 patients, 139 received an autism spectrum disorder diagnosis and 71 received another psychiatric diagnosis. The positive predictive values indicate that these tests correctly identified autism spectrum disorder patients in almost 80% of the referred cases. However, the negative predictive values suggest that only half of the referred patients without autism spectrum disorder were correctly identified. The sensitivity and specificity of each of these instruments were much lower than the values reported in the literature. In this study, the sensitivity of the Ritvo Autism Asperger Diagnostic Scale-Revised was the highest (73%), and the Autism-Spectrum Quotient short forms had the highest specificity (70% and 72%). Based on the similar area under the curve values, there is no clear preference for any of the three instruments. None of these instruments have sufficient validity to reliably predict a diagnosis of autism spectrum disorder in outpatient settings.

Examining the Diagnostic Validity of Autism Measures Among Adults in an Outpatient Clinic Sample

“…10 Best practices in ASD assessment suggest using multiple measures (interviews and questionnaires) and multiple reporters (e.g., self and parent/caregiver). 11,12 An additional barrier to the diagnosis of adults on the spectrum is the comparative paucity of assessment tools that specifically diagnose ASD among adults. Relatively few measures have been modified, psychometrically tested, or developed specifically for adults.…”

“…26 Short forms of the AQ (28-and 10-item versions) found comparable levels of sensitivity (0.77-0.79) but low levels of specificity (0.36-0.41) among an ASD diagnosis-seeking Dutch sample. 12 The Ritvo Autism Asperger's Diagnostic Scale-Revised (RAADS-R) 27 was also developed as a self-report screening tool for ASD characteristics in individuals without cooccurring ID. Utilizing >700 autistic individuals at nine sites, Ritvo et al found the RAADS-R sensitivity, specificity, and test-retest reliability to be in acceptable ranges.…”

“…28 Similar sensitivity and specificity were observed in a Dutch sample of 210 adults in a diagnostic clinic. 12 Previous research has suggested that the ability for current self-report measures to predict a diagnosis of ASD is lacking in an outpatient clinic setting. 12 Self-report measures, in particular, may pose a difficulty for autistic individuals, because in many cases it can require comparison with other's internal states.…”

“…12 Previous research has suggested that the ability for current self-report measures to predict a diagnosis of ASD is lacking in an outpatient clinic setting. 12 Self-report measures, in particular, may pose a difficulty for autistic individuals, because in many cases it can require comparison with other's internal states. 29 One potential explanation for such disparities in self-report is alexithymia, difficulties in identifying and describing one's own emotions.…”

“…33 However, one study that assessed the predictive validity of two short forms of the AQ and the RAADS-R found high levels (80%) of confirmation of ASD diagnosis among adults. 12 The purpose of this study is to explore the correspondence between several adult ASD measures (AQ, RAADS-R, and ADOS) in diagnosing adults on the spectrum at an outpatient adult ASD diagnostic clinic. Although relying on one measure to make an ASD diagnosis is not a recommended approach, it is important to investigate the association between individual measures and a clinical diagnosis.…”