BOCA RATON, FLA. – Severity of autism core symptoms and monitoring of improvements with treatment can be measured with a brief 10-item scale developed by researchers at Ohio State University, Columbus, according to a study presented at a meeting of the New Clinical Drug Evaluation Unit sponsored by the National Institute of Mental Health.
“We don't have a good brief scale to assess core symptoms of autism,” Eric M. Butter, Ph.D., of the pediatrics department at Ohio State, said in an interview at his poster presentation. Although effective treatments for autism have been few, some pharmaceutical agents appear promising, which increases the need for a quick assessment of treatment response, he added. The scale measures response to pharmaceutical and social interventions.
Dr. Butter and his associate James A. Mulick, Ph.D., a professor of pediatrics and psychology at the university, developed the Ohio Autism Clinical Impressions Scale (OACIS) as a symptom-specific version of the Clinical Global Impressions scale. They tested the OACIS's reliability with physicians and psychologists, and compared results with teacher ratings.
In addition to one item that rates global severity of autism, the scale measures impressions about the following nine core symptoms: social interaction, aberrant behaviors, repetitive behaviors, verbal communication, nonverbal communication, hyperactivity, anxiety, sensory sensitivity, and restricted, narrow interests. The rater scores each item on a scale of 1 to 7, with a higher number reflecting greater severity.
A total of 31 children being assessed for an initial diagnosis of pervasive developmental disorder made up the clinical sample assessed by physicians or psychologists. An additional 37 children were assessed by teachers at a specialized school for children with autism spectrum disorders. The children's mean age was 8 years; 62% were diagnosed with autism and 38% with pervasive developmental disorder.
The researchers found a 0.71 interrater reliability in the clinic sample and 0.52 in the school-based group. “Doctors and psychologists agreed better than the teachers did,” Dr. Butter said at the meeting, cosponsored by the American Society for Clinical Psychopharmacology. A reason for the disparity, he speculated, is that “the teachers had broader experience with the children, whereas pediatricians and psychologists were seeing them at the same time.”
Initial findings suggest internal reliability and test-retest reliability were strong. Specifically, internal reliability was 0.92 for the clinical raters and 0.94 for the teachers. Raters repeated the test with a subgroup of the children 1 week later; the test-retest reliability was 0.91 for the clinicians and 0.96 for the teachers.
To test the validity of OACIS, the researchers also tested all participants with the Gilliam Autism Rating Scale (GARS), the Aberrant Behavior Checklist (ABC) irritability subscale, and the Pervasive Developmental Disorders Behavior Inventory (PDDBI). They found that the OACIS total score had a 0.75 correlation with the GARS, 0.57 with the ABC-I, and 0.63 with the PDDBI.
Some of these correlations were surprising, Dr. Butter said. “I'm concerned about the high validity with the GARS–one of our goals is to replace this. I have to figure out why they correlated so well.” He was happy with the lower correlation with the ABC-I. “I wanted it to be divergent because only some kids with autism have irritability.”
The low correlation with the PDDBI was expected, because it is a comparison of a 180-item scale with a 10-item measure, Dr. Butter said.
Data collection is ongoing about how well the OACIS assesses response to pharmacologic or social interventions for autism, Dr. Butter said. Preliminary findings suggest the “improvement index did well, too.” The index had a 0.78 correlation with a language “learning rate” variable devised by the researchers.
“With Risperdal, it will be interesting to see if the scale picks up changes from this medication, as well as other medications in development for core symptoms,” Dr. Butter said.