Supplementary Material for: Validity and Reliability of the Italian Adaptation of GOS.SP.ASS. ’98 Protocol for Assessing Speech in Children with Cleft Lip and Palate

Introduction: The study investigates the psychometric properties of the GOS.SP.ASS. '98 – Italian version protocol for assessing speech in individuals with clefts. Intra- and inter-rater reliability, concurrent validity, criterion validity, and responsiveness of the protocol were examined across specific parameters: hypernasality, hyponasality, nasal emission, turbulence, intelligibility, acceptability, and consonant production.
Methods: The retrospective cross-sectional observational study involved 45 Italian-speaking children with repaired cleft lip and/or palate, evaluated at ages 3 (n=15), 5 (n=15), or 10 years (n=15). For criterion validity, participants were divided into sub-groups based on the severity of speech impairment. For responsiveness, a subset of 18 children who underwent pre- and post-operative assessments following velo-pharyngoplasty was identified.
Results: Results showed good to very good reliability for most parameters, including hypernasality, nasal emission, intelligibility, and acceptability. However, hyponasality and nasal turbulence exhibited lower reliability due to limited variability. Intelligibility scores correlated significantly with the percentage of phonemes correct and percentage of consonants correct, demonstrating concurrent validity. Criterion validity was supported by the GOS.SP.ASS. '98 Italian version protocol's ability to distinguish between groups with different speech impairment levels based on intelligibility scores and articulatory accuracy. Post-surgical assessments revealed significant improvements in hypernasality and nasal emission, underscoring the protocol's responsiveness.
Conclusion: The findings suggest that the GOS.SP.ASS. '98 – Italian version is a reliable and valid tool for the perceptual evaluation of speech outcomes in cleft palate patients, supporting its clinical use to assess speech characteristics and detect changes pre- and post-surgery.