Longitudinal study of the development of obstruent correctness from ages 3 to 5 years in 108 Danish children with unilateral cleft lip and palate: a sub-study within a multicentre randomized controlled trial.

Background: Speech-sound development in preschoolers with unilateral cleft lip and palate (UCLP) as a group is delayed/disordered, and obstruents comprise the most vulnerable sound class.

Aims: To evaluate the development of obstruent correctness (PCC-obs) and error types (cleft speech characteristics (CSCs) and developmental speech characteristics (DSCs)) from ages 3-5 and to investigate possible predictors (error types, velopharyngeal dysfunction (VPD) and gender) of PCC-obs at age 5 in two groups of children with UCLP.

Methods & Procedures: Subgroup analysis was conducted within a multicentre randomized controlled trial (RCT) of primary surgery (Scandcleft Project). A total of 125 Danish children with UCLP received lip and soft palate repair around 4 months of age and early hard palate closure at 12 months (EHPC group) or late hard palate closure at 36 months (LHPC group). Audio and video recordings of a naming test were available for 108 children at ages 3 and 5, and recordings were transcribed phonetically by blinded raters.

Outcomes & Results: PCC-obs scores increased significantly from ages 3-5 in both groups, but with small effect sizes in the EHPC group that had higher scores at age 3 than the LHPC group. DSCs decreased in both groups whereas CSCs only decreased in the LHPC group that had more CSCs at age 3 than the EHPC group. The frequency of CSCs at age 3 was a significant predictor of PCC-obs scores at age 5 in both groups. DSCs significantly improved the logistic regression model in the EHPC group, whereas VPD and gender did not significantly improve the model in either group.

Conclusions & Implications: Although PCC-obs developed significantly from ages 3 to 5, children with UCLP as a group did not catch up to typically developing Danish children at age 5. Furthermore, the LHPC group at age 5 did not reach the 3-year level of the EHPC group, which means that delaying hard palate closure until age 3 is detrimental to obstruent development. Both CSCs and DSCs at age 3 were important predictors of PCC-obs at age 5 and should be considered when determining need for intervention.