Many young children with Autism Spectrum Disorder (ASD) respond well to intensive early intervention and therefore early diagnosis is important. However, it is also critical to screen for ASD at older ages as well because signs can be missed in children who are young and have not yet regressed, as well as in those who do not show problems until school age because they are mildly affected. The PDDBI-SV (containing 18 items) was developed as a screening tool to help clinicians quickly identify children at risk for ASD, and covers a broader age span (18 months to 12-1/2 years of age) than that found with most other screening instruments. It was derived from the PDD Behavior Inventory, a reliable and valid informant-based assessment tool. Previous data (Cohen et al., 2010) indicated that the PDDBI Social Discrepancy Score, a measure of social competence, has excellent sensitivity (98%) and specificity (93%) and so the PDDBI-SV score was based on this measure. We found that the PDDBI-SV score agrees very well with the Social Discrepancy Score, is reliable, agrees well with other instruments, and reflects the severity of ASD.
Objectives:
The aim of this study was to develop a scoring system for a brief screening version of the PDDBI and to evaluate its reliability and validity.
Methods:
Using the original PDDBI standardization sample of 369 cases, multiple regression analyses were computed to identify a subset of 18 items that best correlated with the Social Discrepancy Score. The internal consistency, one year test-retest, and mother-father interrater reliability were then computed. Diagnostic validity (ROC analyses), and criterion-related validity were examined in terms of agreement with the M-CHAT, CARS, and Social Responsiveness Scale (SRS). PDDBI domain profiles were also examined as a function of degree of severity of the composite score (in SD units) using multivariate analysis of variance.
Results: A composite score (called the Social Deficit Score; SOCDEF) was identified that correlated highly (r=-0.97) with the PDDBI Social Discrepancy Score. Internal consistency reliability (alpha) was 0.87 (n=100); one-year test-retest reliability was 0.74 (n=38); and the mother-father intraclass r was 0.62 (n=121). ROC analyses (n=100; 50 ASD; 50 matched controls) yielded an area under the curve (AUC) value of 0.96 (C95 = 0.92 - 0.99). Correlation with the M-CHAT (n=25) was 0.73 for the total score and 0.67 for the number of critical items failed. The correlation between the SOCDEF score and the SRS was 0.83 (n=26) and the correlation with the CARS was 0.54 (n=84). PDDBI domain profiles were found to reflect increasing levels of severity (manifested by greater problem behaviors and fewer communicative skills) as the SOCDEF score increased in value.
Conclusions:
The SOCDEF score appears to be both reliable and valid. The PDDBI-SV should therefore serve as a useful Level 1 screening device for social deficits in children between 18 months and 12-1/2 years. It also should serve as a brief quantitative measure of ASD severity.
See more of: Clinical Phenotype
See more of: Symptoms, Diagnosis & Phenotype