Lower sentence comprehension than word comprehension in preschool children who stutter predicts persistent stuttering and stuttering severity at school-age

This study investigated whether preschool language profiles predict persistent stuttering and stuttering severity at school-age, and whether children who stutter (CWS) with specific language profiles respond differently to RESTART-DCM treatment versus the Lidcombe Program (LP). Data from 149 CWS in a longitudinal follow-up of the RESTART randomised trial were analysed. Four difference scores within individual language profiles at preschool age (3;0–6;3 years) were examined: word comprehension minus sentence comprehension quotient (∆WC-SC), word comprehension minus word production quotient (∆WC-WP), word production minus sentence production quotient (∆WP-SP), and sentence comprehension minus sentence production quotient (∆SC-SP). Outcome measures at school age (8–17 years) included Stuttering Severity Instrument scores from trained observers and subjective severity ratings from parents, speech-language pathologists, children, and teachers using Yairi & Ambrose's eight-point scale. Results revealed that children with persistent stuttering (CWS-per) showed imbalanced language profiles at preschool age, particularly with sentence comprehension lagging behind word comprehension. In contrast, children with transient stuttering (CWS-tran) demonstrated balanced profiles. The word-sentence comprehension difference score significantly predicted persistent stuttering and stuttering severity at school age, especially in boys. Treatment type showed no significant effect. In conclusion, an imbalanced preschool language profile, specifically when sentence comprehension lags behind word comprehension, represents a risk factor for persistent stuttering at school age in boys. While this finding has clinical implications, no evidence suggested differential treatment benefits between RESTART-DCM and LP based on the preschool language profile.