Psychometric properties of the Sinhala version of the Swanson, Nolan, and Pelham rating scale (SNAP-IV) Parent Form in healthy children and children with ADHD.

OBJECTIVE: The present study aimed to translate and adapt the Parent Form of the MTA Version of the Swanson, Nolan, and Pelham ADHD/ODD rating scale (SNAP-IV) into Sinhala and examine its psychometric properties. METHOD: The MTA version of the SNAP-IV was translated into the Sinhala language by adhering to the WHO translation and adaptational process. The final Sinhala SNAP-IV (S-SNAP-IV) was administered to parents of 412 healthy children and adolescents (age: 6-18 years), and 272 children and adolescents with ADHD (age: 4-19 years). Internal consistency and factor structure of the S-SNAP-IV were determined in each sample. RESULTS: Conforming to that of the original English version, the S-SNAP-IV showed a three-factor structure (inattention, hyperactivity/impulsivity, and oppositional defiant disorder) in each sample, except for three item deviations (10,11, and 13) in the healthy sample. The S-SNAP-IV showed excellent internal consistency in the total sample (Cronbach's alpha = 0.97), healthy sample (Cronbach's alpha = 0.90), and the clinical sample (Cronbach's alpha = 0.94). The S-SNAP-IV also showed good discriminative validity: Only 1.5% of the healthy sample exceeded the cut-off scores in any domain, whereas all newly diagnosed, unmedicated children were S-SNAP-IV positive in at least one domain. CONCLUSIONS: The findings suggest that the three-factor model fits the S-SNAP-IV, and it clearly distinguishes children with ADHD from non-ADHD children. We conclude that the S-SNAP-IV possesses satisfactory psychometric properties-consistent with the MTA English version and its translations into other languages-making it a reliable and valid instrument for screening children with ADHD.