Diagnosis of autism spectrum disorders in 2‐year‐olds: a study of community practice

As awareness of the early signs of autism spectrum disorders (ASD) increases,more physicians routinely screen for the presence of the disorder and children are referred to community diagnostic clinics with suspicion of the disorder at younger ages.The American Academy of Pediatrics has suggested routine screening for ASD at the 18- and 24-month well child visits (Johnson, Myers, & American Academy of Pediatrics Council on Children With Disabilities, 2007) which can lead to an increase in referrals for diagnosis at early ages. Several studies have foundthat ASD can be reliably diagnosed in children under 3 years of ageby experienced, highly trained clinicians in specialty clinic and research settings(Charman et al., 2005; Lord et al., 2006; Turner & Stone, 2007) and that the greatest accuracy in diagnosis of young children is achieved when using a standardized parent interview and a standardized observational measure in combination with clinical judgment (Corsello et al., 2007; Lord et al., 2006; Risi et al., 2006). Given the emphasis on appropriate early intervention and the expense of intensive early intervention services, diagnostic accuracy is crucial. There are relatively few standardized diagnostic measures that have demonstrated strong discriminative ability in young children and predictive validity over time (Lord et al., 2006). Two of the most well validated and commonly used measures in research studies are the Autism Diagnostic Observation Schedule (ADOS; Lord, Rutter, DiLavore, & Risi, 2001) and the Autism Diagnostic Interview – Revised (ADI-R; Rutter, Le Couteur, & Lord, 2003). These measures are considered the gold standard in research protocols and have become widely known among clinical professionals. Both are available through a U.S. Publisher, but only the ADOS has become widely used by cliniciansbecause the length of the ADI-R makes it difficult to incorporate into clinical practice.Additionally, studies using the ADI-R with children under 3 years of age have reported mixed results, with several reporting an under-identification of children with ASDprimarily due to less children meeting criteria on the restricted behavior area(Ventola et al., 2006; Wiggins & Robins, 2008). While the ADOS is widely available and recommended as one of the appropriate standardized measures recommended in several Best Practice Guidelines as an appropriate standardized diagnostic observation tool(California Department of Developmental Services, 2002; Filipek et al., 2000; Filipek et al., 1999; National Research Council, 2001), little is known about the effectiveness of this measure when administered by community clinicians who have not met the research training requirements and are not using the ADOS in combination with ADI-R. The results from studies of the ADOS conducted by community based clinicians that have achieved reliability are variable depending on clinic type and population evaluated. In an ASD specific clinic, the ADOS demonstrated good sensitivity and specificityin a sample of 2 to 8 year old children (Mazefsky & Oswald, 2006). On the other hand, the ADOS was not as specific and resulted in more false-positive ASD classifications in a complicated community based general developmental clinic sample of 2 to 16 year old children(Molloy, Murray, Akers, Mitchell, & Manning-Courtney, 2011). Clinicians working outside an ASD specialty clinic or research setting often have less rigorous training on standardized diagnostic measures, see a lower percentage of children with ASD, and are more likely to evaluate children who are diagnostically complex(Molloy et al., 2011). Clinic-referred samples may be more likely to include children from minority backgrounds, parents with a lower level of education, and families with more disadvantaged circumstances, all factors that have been associatedwith increased age of diagnosis (Mandell, Ittenbach, Levy, & Pinto-Martin, 2007; Mandell, Novak, & Zubritsky, 2005; Shattuck et al., 2009). Complicated diagnostic presentations, combined with the often limited training of community clinicians on research based measures, may affect measurement accuracy when used in community programs. Additionally, most studies on community based samples compare the classification on the measure with clinical diagnosis that included the scores and observations from the measures. This decreases the objectivity and independence of the clinical diagnosis. The CDC has developed a method for giving a diagnosisbased on a record review(Centers for Disease Control, 2007). This method allows for an outside reviewer to provide a diagnosis without scores or classifications on measures. The ADI-R is also available but isless commonly used in clinical practicegiven the difficulty of obtaining insurance funding for the lengthy interview. Aside from the ADI-R, there are very few diagnostic measures based on parent report. For this reason, many clinicians constrained by funding have resorted to using screening measures as well as parent questionnaires to obtain standardized parent information to augment their clinical interview. One such screening measure, the Social Communication Questionnaire (SCQ; Rutter, Bailey, & Lord, 2003), is based on the ADI-R and is more widely utilized given its brevity. The SCQ has been demonstrated to discriminate ASD from Non-Spectrum (NS) diagnoses in children under age 5 with a reduced cut-off(Corsello et al., 2007) but little is known about how accurate it is with children under age 3. Another screening measure, the Modified Checklist for Autism in Toddlers (M-CHAT; Robins, Fein, Barton, & Green, 2001) is widely used in children under the age of 30 months (Kleinman et al., 2008; Pandey et al., 2008; Robins et al., 2001). While the M-CHAT can accurately identify many children with ASD, some children without an ASD screen positive for the disorder (Pandey et al., 2008), especially when a follow-up interview is not employed which is often the case in community clinics (Pandey, et. al., 2008; Robins & Dumont-Mathieu, 2006). Despite this weakness, without other options clinicians may turn to this screener when evaluating very young children referred for an ASD. Most of the evidence for making an accurate diagnosis in young children is based on studies conducted with experienced and highly trained staff in research settings. We investigated whether these results can be replicated within a community based sample in a general developmental evaluation clinic with very young children when the clinician, in this case a clinical psychologist, has not received intensive training on standardized measures. The present study was designed to addresses the following questions: 1) How well does the ADOS perform when used by community clinicians in a young community based sample? 2) Does using a brief parent measure (M-CHAT or SCQ) in combination with the ADOS improve diagnostic accuracy in this young community sample?