Screening for intellectual disability in autistic people: A brief report

Background: There is high co-occurrence between intellectual disability and Autism Spectrum Disorder (ASD). It is important to identify people who have both conditions for clinical and research reasons. This study explored if the Child and Adolescent Intellectual Disability Screening Questionnaire (CAIDS-Q) and Learning Disability Screening Questionnaire (LDSQ) could accurately identify intellectual disability in autistic children and adults respectively. Method: Pre-existing CAIDS-Q data for 40 autistic children and LDSQ data for 27 autistic adults were used. The participants were classified as likely to have an intellectual disability or not based on the age-appropriate cut-off score on the relevant screening tools. This was compared with their clinical diagnosis of intellectual disability. Results: The sensitivity, specificity, and positive and negative predictive values, for the CAIDS-Q were 93.1%, 88.5%, 90% and 92% respectively. The corresponding figures for the LDSQ were 75%, 95.6%, 75%, and 95.6%. Conclusions: The values for the CAIDS-Q were broadly consistent with figures found in previous research. The sensitivity and PPV figures for the LDSQ, were somewhat lower. The specificity and sensitivity values for both measures were above the threshold for levels that are generally considered to be acceptable for a developmental screening tool. The results suggest that the CAIDS-Q and LDSQ may be appropriate measures to screen for intellectual disability in autistic people