Your Family Physician

May 11, 2009 (Chicago, Illinois) — Researchers have come up with a relatively simple tool that could be the answer to many clinicians' wish for a practical screen for autism in very young children. Called the Systematic Observation of Red Flags (SORF), the instrument distinguishes between 18- to 24-month-olds with autism spectrum disorders (ASDs) and those with either developmental delays or who are healthy, normal children.

A study presented here at the 8th Annual International Meeting for Autism Research indicates that children who have at least eight of the 20 "red flags" in SORF have a high probability of having autism.

In 2007, members of the American Academy of Pediatrics' Council on Children With Disabilities called for pediatricians to systematically screen all infants for ASDs at 18 and 24 months of age (Johnson CP et al. Pediatrics. 2007;120:1183-1215).

However, there were no reliable physician-administered tools for ASD screening of the general infant population; the Modified Checklist for Autism in Toddlers (M-CHAT) and the Infant-Toddler Checklist (ITC) are usually relied upon for first-line, parent-reported screening. The SORF could help fill that gap, notes Geri Dawson, PhD, chief scientific officer for Autism Speaks.

"This is like a second-level screening; it complements the M-CHAT," Dr. Dawson told Medscape Psychiatry. "The main point is that it's very exciting to see a screening tool being developed that can be easily used in pediatricians' offices, so these kids can be identified early and can get into early intervention, so they can get the best outcomes possible."

Not All "Red Flags" Useful

Lead investigator Amy Wetherby, PhD, from Florida State University, in Tallahassee, and colleagues published a paper last year on a study of the combined use of the ITC and a clinician-administered, videotape-based screener called the Communication and Symbolic Behavior Scale Developmental Profile (CSBS DP) Behavior Sample (Wetherby AM et al. Autism. 2008;12:487-508).

The CSBS DP Behavior Sample involves a warm-up of about 10 minutes and a 30- to 40-minute videotaped session in which the infant is tested for communication and comprehension abilities.

The team selected its subjects from a pool of 6581 children recruited by the Florida State University FIRST WORDS Project. The children's parents were asked to complete the ITC, which has 24 questions about the child's developmental milestones and 1 question about whether the parent is concerned about the child's development. The ITC provides a first-line indicator of whether the child is at risk for communication delay; it does not determine whether a child has ASD.

Next, parents whose children screened positive on the ITC or who responded in the affirmative to the ITC question about concerns about the child's development underwent the CSBS DP Behavior Sample videotaping session. The investigators reviewed the videotapes and scored the children for the presence of 29 "red flags." This takes about 30 minutes per videotape.

They found that 9 of the 29 red flags were not useful in discriminating between children with and without ASDs. Therefore, they focused on the remaining 20 red flags as true indicators of the presence of ASDs and dubbed this constellation the SORF.

These 20 items probe for the presence of impairment in social interaction, repetitive behaviors and fixated interests, impairment in communication, and difficulties with emotional regulation. A child can score from zero to 2 for each of the red flags; hence the highest possible score on the SORF is 40 and the lowest is zero.

Quicker Screening Tool?

Dr. Wetherby and her coinvestigators found that a score of 10 or more on the SORF yields a sensitivity of 0.87 for an ASD diagnosis. The specificity is 0.81, the positive predictive value is 0.76, and the negative predictive value is 0.94.

They also found that the presence of eight red flags is also a useful cutoff for ASD; it has a sensitivity of 0.87, a specificity of 0.84, a positive predictive value of 0.79, and a negative predictive value of 0.91. A total of 60 children in their sample were found to have ASD.

A check of correlations with other ASD measures, such as the gold-standard Autism Diagnostic Observation Schedule, showed very high levels of agreement between these and the SORF for both the subjects' total score from the 20 items and the total number of red flags.

"We are beginning to study a checklist of fewer than 20 of the red flags to compare with our more detailed list," said Dr. Wetherby. "If it achieves the same accuracy, then we can use this as a quicker screening measure. But we don't yet know if that is feasible."

The study is supported by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health, the Centers for Disease Control and Prevention, and the US Department of Education. Dr. Wetherby discloses that as an author of the Communication and Symbolic Behavior Scales, she receives royalties on the sales of the test.

Source : http://www.medscape.com/viewarticle/702626?sssdmh=dm1.470812&src=nldne