Childhood Autism Tool - Trivandrum (CAT-T) - Development and Validation.

Objectives: To develop and validate a culturally appropriate measure for the diagnosis of ASD among children between 2 and 6 y of age in Kerala.

Methods: This qualitative study was conducted among 200 children who were consecutively recruited over a period of 18 mo. The development of the new measure was based on the Consensus based Standards for the selection of health Measurement Instruments (COSMIN) protocol. The face and content validity were already established while developing the measure. The convergent and divergent validity of CAT-T were measured against Childhood Autism Rating Scale (CARS) and Vineland Social Maturity Scale (VSMS) respectively. The construct validity of CAT-T was evaluated using exploratory factor analysis.

Results: A 39-item measure was developed by using the 8 steps recommended for psychosocial measure development. The 39 items of the tool were subjected to factor analysis and finally a tool having 24 items was developed (CAT-T). Convergent validity of the measure with CARS (r = 0.67, p = 0.0001) and divergent validity with VSMS (r = -0.50, p = 0.0001) were moderate. The tool has good test retest reliability (ICC = 0.86), inter rater reliability (ICC = 0.89), and internal consistency of 24-item CAT-T was very high (Cronbach's alpha = 0.86). The construct validity of CAT-T demonstrated a 7- factor structure that explained 66.22% of the variance.

Conclusions: A 24-item final measure, the Childhood Autism Tool-Trivandrum (CAT-T), was developed. The measure CAT-T has adequate validity and reliability parameters.