Practice Parameter: Screening and Diagnosis of Autism; EP Magazine Will Be Exploring the Causes, Effects and Treatment of Autism through 2003. as a Basis for Planning These Articles, and to Invite Comment and Contributions, We Are Publishing the "Practice Parameter: Screening and Diagnosis of Autism" from the Report of the Quality Standards Subcommittee of the American Academy of Neurology and the Child Neurology Society. (EP on Autism)

Article excerpt

Level one: routine developmental surveillance and screening specifically for autism. Analysis of the evidence. When and how often should developmental surveillance/screening be performed? Approximately 25% of children in any primary care practice show developmental issues. However, fewer than 30% of primary care providers conduct standardized screening tests at well-child appointments. The American Academy of Pediatrics (AAP) stresses the importance of a flexible, continual developmental surveillance process at each well-child visit, and recommends eliciting and valuing parental concerns, probing regarding age-appropriate skills in each developmental domain, and observing each child.

What are the appropriate developmental screening questionnaires that provide sensitive and specific information? Developmental screening tools have been formulated based on screening of large populations of children with standardized test items. Sensitive and specific developmental screening instruments include: the Ages and Stages Questionnaire, the BRIGANCE Screens, the Child Development Inventories and the Parents' Evaluations of Developmental Status.

The Denver-II (DDST-II, formerly the Denver Developmental Screening Test-Revised) has been the traditional tool used for developmental screening, but research has found that it is insensitive and lacks specificity. The Revised Denver Pre-Screening Developmental Questionnaire (R-DPDQ) was designed to identify a subset of children who needed further screening. However, studies have shown that it detected only 30% of children with language impairments and 50% of children with mental retardation.

How are conventional developmental milestones defined? Conventional developmental language milestones are based on normative data from numerous standardized language instruments for infants. Lack of acquisition of the following milestones within known accepted and established ranges is considered abnormal: no babbling by 12 months, no gesturing (e.g., pointing, waving bye-bye) by 12 months; no single words by 16 months; no 2-word spontaneous (not just echolalic) phrases by 24 months; and any loss of language or social skills at any age. Failure to meet these milestones is associated with a high probability of a developmental disability.

Do parents provide reliable information regarding their child's development? Several studies encompassing 737 children showed that parental concerns about speech and language development, behavior, or other developmental issues were highly sensitive (i.e., 75% to 83%) and specific (79% to 81%) in detecting global development deficits. However, the absence of such concerns had modest specificity in detecting normal development (47%). An additional study that combined parental concern with a standardized parental report found this to be effective for early behavioral and developmental screening in the primary care setting.

Can autism be reliably diagnosed before 36 months of age? Because there are no biological markers for autism, screening must focus on behavior. Recent studies comparing 109 autistic and 33 typically developing children demonstrated that problems with eye contact, orienting to. one's name, joint attention, pretend play, imitation, nonverbal communication, and language development are measurable by 18 months of age. These symptoms are stable in children from toddler age through preschool age. Retrospective analysis of home videotapes has also identified behaviors that distinguish infants with autism from other developmental disabilities as early as 8 months of age.

Current screening methods may not identify children with milder variants of autism, those without mental retardation or language delay, such as verbal individuals with high-functioning autism and Asperger's disorder, or older children, adolescents, and young adults.

Is there an increased risk of having another child with autism (recurrence)? …

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