Development and validation of red flags for early detection of dyslexia in Sinhala (REaDDS tool) for dyslexia...

Sinhala is an alpha-syllabic language. However, majority of dyslexia screening tools are developed in English. Despite growing evidence on language skills associated with dyslexia, a linguistically and culturally appropriate standardized tool is not available for Sinhala-speaking children. This study aimed to develop and validate a screening instrument to identify early signs of dyslexia, focusing on language-based skills in children aged 4-6 years. The Red Flags for Early Detection of Dyslexia in Sinhala (REaDDS) tool was developed through two phases. Study 01 encompassed tool development, Delphi review, pilot testing, and pretesting. Study 02 focused on psychometric evaluation. The REaDDS tool comprises a test kit, administration manual, and score sheets, assessing four domains: (1) phonological processing, (2) morphology, (3) other language skills, and (4) visual processing and cognitive abilities. The initial 24 subsets were refined to 19 following expert review and pilot testing during Study 01. In Study 02, the refined tool was administered to 214 typically developing children and 125 with dyslexia. Validity and reliability analyses were conducted using data from 57 typically developing children and 79 with dyslexia aged 6-6.99 years. Cronbach's alpha values ranged from 0.777 to 0.930, indicating acceptable to excellent internal consistency. Inter-rater reliability was strong (ICC = 0.75-0.90), and sensitivity and specificity were acceptable across domains (AUC > 0.75). Item-level Content Validity Index (I-CVI) values exceeded 0.78 for all items. The REaDDS tool represents the first comprehensive, language-based, user-friendly, standardized dyslexia screening instrument for Sinhala, with evidence of validity and reliability.