Revisiting the Cutoff Criteria of Intelligibility in Context Scale-Traditional Chinese

Background This study evaluated the validity of the Intelligibility in Context Scale-Traditional Chinese (ICS-TC) and explored its potential as a screening tool for speech sound disorder (SSD) in Cantonese-speaking children in Hong Kong. Method The parents of 789 Cantonese-speaking children aged between 2;4 (years;months) and 6;9 completed the ICS-TC. Children were categorized into 2 groups: (a) an SSD group whose initial consonant scores in a standardized assessment were equal to or lower than -1.33 SD and (b) a non-SSD group whose scores were higher than -1.33 SD. The screening accuracy of ICS-TC using a previously proposed cutoff was appraised. A cutoff score for each age group was determined when the effect of age on the ICS-TC mean scores was significant and the corresponding screening accuracy was appraised. Results When the previously proposed cutoff was applied to the whole sample, sensitivity and specificity were unsatisfactory. Given the significant age effect, new cutoff scores for each age group were estimated. The new cutoff scores only led to remarkably improved screening accuracy for Age Group 4 (4;0-4;5) but little to no improvement for other age groups. Conclusions There is limited clinical use of ICS-TC as a screening tool with a single cutoff score for children at different ages. Its clinical utility might be limited to children of about 4 years of age, where ICS-TC scores demonstrated the best differentiation between children with and without speech concerns. Future studies could refine the screening criteria to further minimize the number of false positives.