“For clinical researchers, the closest thing to a gold standard for the assessment of child and adolescent depression is a semi-structured clinical interview, typically administered not just to the child but to a parent or other caregiver as well,” said David A. Cole of the Department of Psychology and Human Development at Vanderbilt University in Tennessee, and lead author of a new study examining the validity of the IRT for adolescent depression. “The application of item response theory (IRT) to semi-structured clinical interview data can simultaneously advance the understanding of psychopathology and enhance the fidelity of its measurement.”
Cole said, “Analyzing symptom-level information derived from such measures can provide insights into the structure of the underlying depression construct, lead to the psychometric enhancement of these measures, and eventually enable researchers to derive more information from such interviews of depressed children and adolescents.” To test his theory, Cole examined data from 3,403 youth who were screened using the Kiddie Schedule of Affective Disorders and Schizophrenia for School-Aged Children (K-SADS). He found that the IRT was useful in identifying the severity of the depression based on the symptoms reported. “Some symptoms may be evident at relatively mild levels of the disorder, whereas other symptoms may only emerge at very severe levels,” said Cole. “In other words, severe depression may be characterized by symptoms that are not often evident in mild depression. If the severity of depression is assessed simply by counting the number of symptoms, then all symptoms are treated as though they were of equal severity or importance and other valuable information that could be derived from the assessment process potentially is ignored.”
Cole also pointed out that the IRT was effective at uncovering nuances of symptoms in the subclinical range that were not revealed in the standard clinical interview, and believes this is important for clinicians treating adolescents at risk for depression. He added, “The inclusion of even one extra response option to indicate the subclinical presence of each symptom can substantially enhance the researcher’s capacity to detect a treatment difference.”
Cole, David A., Li Cai, Nina C. Martin, Robert L. Findling, Eric A. Youngstrom, Judy Garber, John F. Curry, Janet S. Hyde, Marilyn J. Essex, Bruce E. Compas, Ian M. Goodyer, Paul Rohde, Kevin D. Stark, Marcia J. Slattery, and Rex Forehand. “Structure and Measurement of Depression in Youths: Applying Item Response Theory to Clinical Data.” Psychological Assessment 23.4 (2011): 819-33. Print.
© Copyright 2011 by By John Smith, therapist in Bellingham, Washington. All Rights Reserved. Permission to publish granted to GoodTherapy.org.
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