Objectives: To examine (1) concurrent validity of the ADOS, CARS, and SRS; (2) categorization of children’s diagnostic status or symptom severity across measures; and (3) stability of their diagnostic status.
Methods: Data for this study were collected on 140 children (ages 3 – 5) as part of a larger study comparing the efficacy of school-based, comprehensive treatment models for preschoolers with ASD. The reported data were collected across four states (CO, NC, FL, and MN), and at the beginning and end of one school year (range of 6-9 months between assessment time points).Trained and reliable research staff administered the ADOS and CARS. Parents of children enrolled in the study completed the SRS. Correlational analysis was used to determine concurrent validity, cross-tabulations were performed to examine children’s categorizations across measures, and weighted kappas were used to examine diagnostic stability.
Results: The ADOS severity score was significantly correlated with the CARS total score (r = .47) but not the SRS total score (r = .09). The CARS and SRS were significantly correlated with each other (r = .26). Cross-tabulations were performed to examine children’s diagnostic and severity classification across the three measures. Forty-five percent of the sample was similarly classified across all three measures, 24% on the ADOS and SRS but not CARS, 16% on the ADOS and CARS but not SRS, 13% on the ADOS but not CARS or SRS, and 2% on the SRS but not ADOS or CARS. In examining longitudinal data, children’s scores on each measure at the beginning of the school year were significantly correlated with their end of the year scores; the weighted kappas values were (ADOS, k = .35; CARS, k = .61; SRS, k = .61). (Note: Per Chlebowski et al. 2010, the CARS cut-off score of 25 was used).
Conclusions: Diagnostic status and symptom severity is a mostly stable construct across measures. Children’s scores on the measures were correlated with the exception of the SRS and ADOS. This may reflect method variance in that parents completed the SRS; however, research staff completed the ADOS and CARS. However, for the near majority of the sample, children were similarly classified across the three measures. Further, children’s diagnostic status remained largely unchanged from the beginning to the end of the school year; although kappa values were lower for the ADOS this was primarily an artifact of using weighted kappas.
See more of: Clinical Phenotype
See more of: Symptoms, Diagnosis & Phenotype