Effectiveness of a Province-Wide Early Intervention Program for Preschoolers with ASD

Background:  Translation of efficacious early intervention methods into community practice is a challenge in many jurisdictions, especially for publicly funded services. Nova Scotia (NS) implemented a model of relatively low-intensity (15 hours/week) and short duration (1 year) intervention for ASD in 2005 (Bryson et al., 2007). The program employs Pivotal Response Treatment (PRT) as the primary treatment modality, and entails training and in vivo coaching of parents to complement the shorter period of 1:1 intervention by therapists. The primary target of intervention is social communication skills. Initial data for N = 45 suggested positive outcomes after one year of intervention (Smith et al., 2010).

Objectives:  To examine key outcomes for a larger cohort of children and families who participated in the PRT-based NS program.

Methods:  Participating families were enrolled in the clinical program, with eligibility based only on age under 6 years and a clinical diagnosis of ASD.  Research staff conducted independent assessments at baseline, and after 6 and 12 months of intervention. Data from all three timepoints were available for N = 76. Key outcomes (and associated measures) included language (PLS IV), IQ (Merrill-Palmer-Revised Scales), adaptive behaviour (VABS II), behaviour problems (CBCL 1½ -5) and autism symptoms (SRS).

Results: Children made meaningful gains in expressive and receptive language age equivalent scores (p<.001) and ratio scores (p < .05). After one year, 37% and 46% of children experienced greater gains in expressive and receptive language, respectively, than expected for typical development. In addition to better language/communication skills, children experienced large increases in cognitive standard scores (p<.001), with an average increase of 13.2 IQ points. After 1 year, 43% scored within the average IQ range, versus 12% at program entry. Children’s overall adaptive functioning also improved significantly (p < .001), as did child behaviour problems (p < .05). However, autism symptoms improved only for a higher-functioning subgroup (p < .05).

Conclusions:  One-year outcomes for children in this less-intensive program of short-term therapist intervention, combined with parent training in PRT, appear similar to published results for more intensive “traditional” models of EIBI. Substantial effect sizes were obtained for an explicitly targeted outcome (expressive communication), as well as for generalized, collateral improvements (e.g., receptive language, IQ). There is also evidence of differential responsiveness to intervention for children at different levels of initial cognitive functioning. Our next analyses will examine closely this and other factors that predict outcomes in this program.