A randomised-controlled trial of a pre-emptive intervention for infants showing early behavioural risk signs of autism spectrum disorder

‘High functioning autism’ is a term often used for individuals with autism spectrum disorder without an intellectual disability. Over time, this term has become synonymous with expectations of greater functional skills and better long-term outcomes, despite contradictory clinical observations. This study investigated the relationship between adaptive behaviour, cognitive estimates (intelligence quotient) and age at diagnosis in autism spectrum disorder. Participants ( n = 2225, 1–18 years of age) were notified at diagnosis to a prospective register and grouped by presence ( n = 1041) or absence ( n = 1184) of intellectual disability. Functional abilities were reported using the Vineland Adaptive Behaviour Scales. Regression models suggested that intelligence quotient was a weak predictor of Vineland Adaptive Behaviour Scales after controlling for sex. Whereas the intellectual disability group’s adaptive behaviour estimates were close to reported intelligence quotients, Vineland Adaptive Behaviour Scales scores fell significantly below intelligence quotients for children without intellectual disability. The gap between intelligence quotient and Vineland Adaptive Behaviour Scales scores remained large with increasing age at diagnosis for all children. These data indicate that estimates from intelligence quotient alone are an imprecise proxy for functional abilities when diagnosing autism spectrum disorder, particularly for those without intellectual disability. We argue that ‘high functioning autism’ is an inaccurate clinical descriptor when based solely on intelligence quotient demarcations and this term should be abandoned in research and clinical practice.

Key Points Question Does preemptive intervention compared with usual care reduce the severity of autism symptoms and the likelihood of an autism spectrum disorder (ASD) diagnosis in infants showing early signs of ASD? Findings In this randomized clinical trial of 103 infants showing early behavioral signs of ASD, preemptive intervention led to a statistically significant reduction in the severity of ASD behaviors across early childhood. Infants who received the preemptive intervention had lower odds of meeting diagnostic criteria for ASD (7%) than those who received usual care (21%) at age 3 years, with a number needed to treat of 7 participants. Meaning This study found that a preemptive intervention reduced ASD diagnostic behaviors when used at the time atypical development first emerges during infancy.

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Delays within the motor domain are often overlooked as an early surveillance marker for autism. The present study evaluated motor difficulties and its potential as an early predictive marker for later autism likelihood in a cohort of infants (N = 96) showing early behavioral signs of autism aged 9–14 months. The motor domain was evaluated using the motor subscales of the Mullen Scales of Early Learning at baseline, and at a 6‐month follow‐up. The Autism Diagnostic Observation Schedule – Toddler Module (ADOS‐T) was completed at follow‐up as a measure of autism likelihood. Motor difficulties were common at baseline, with 63/96 (65.6%) infants scoring very low or below average in the gross motor domain and 29/96 (30.2%) in the fine motor domain. At follow‐up, gross motor difficulties had resolved for many, with 23/63 (36.5%) infants maintaining these difficulties. Fine motor difficulties resolved in fewer infants, with 20/29 (69.0%) continuing to present with fine motor delays at follow‐up. Adjusted linear regression models suggested that fine motor scores at baseline (β = −0.12, SE = 0.04) and follow‐up (β = −0.17, SE = 0.05) were associated with higher ADOS‐T scores; with difficulties across both timepoints (β = 5.60, SE = 1.35) the strongest (largest in magnitude) association with ADOS‐T scores of the predictors examined. Motor difficulties are prominent in children displaying emerging signs of autism, with persistent fine motor difficulties predictive of the developing autism phenotype. The findings indicate the potential clinical value of including evaluation of motor skills within early autism surveillance measures. Lay Summary This prospective study evaluated motor development over a 6‐month period in infants showing early behavioral signs of autism. Atypical motor development was a common feature of infants showing early signs of autism and persistent fine motor difficulties were predictive of the emerging autism phenotype.

Often included within ‘high-risk sibling’ studies, the Autism Observation Scale for Infants (AOSI) has only one independent replication study and no evaluation with community-ascertained cohorts. We administered the AOSI and established clinical measures with 103 infants (68% male) at ‘high autism likelihood’ on the Social Attention and Communication Surveillance - Revised (SACS-R) tool, at 9–14 months of age and again 6 months later. AOSI Total scores showed adequate internal consistency and strong inter-rater agreement (live- or video-coded) and were approximately normally distributed at each visit. Modest significant associations presented between Time 1 AOSI scores and concurrent developmental/adaptive skills measures. Concurrent associations were stronger at Time 2, particularly between AOSI Total and Autism Diagnostic Observation Schedule (ADOS) Social Affect scores. AOSI scores were only moderately associated across Time 1 and 2 assessments, as were Time 1 AOSI with Time 2 ADOS scores. These data from a clinically indicated cohort broadly replicate previous AOSI validity accounts from ‘high-risk sibling’ studies, particularly beyond the first year. Strong inter-rater agreement indicates viable AOSI inclusion within protocols necessitating blinded evaluation (e.g. intervention trials). Moderate within-participant stability suggests that, like ‘high-risk siblings,’ community-ascertained infants experience variable early trajectories. Lay Abstract We investigated whether a commonly used research assessment – the Autism Observation Scale for Infants (AOSI) – accurately measures autism behaviours among infants showing early signs of autism identified within the community. The AOSI is often included in studies tracking the development of infants at increased likelihood of autism, such as the infant siblings of diagnosed children. However, the suitability of this measure has not previously been tested with community-referred infants. We administered the AOSI with infants when aged 9 to 14 months and again 6 months later. Our researchers – independent of the AOSI development team and newly trained on this measure – were able to administer the brief interactive assessment and score it accurately. The infants’ AOSI scores were linked to their scores on other established and validated clinical assessments, particularly at the second visit when average age was 18 months. Stronger correspondence of AOSI and other scores at this second visit suggests early autism behaviours are better established and more consistent by 18 months of age, even though these infants showed clear enough signs of possible autism to prompt referral to our study around 12 months of age. However, the moderate association of AOSI scores over time suggests that, like infant siblings – who mostly do not develop autism – community-identified infants showing early signs may also have variable developmental pathways in early life.

ImportanceThe growing global prevalence of autism spectrum disorder (ASD) is associated with increasing costs for support services. Ascertaining the effects of a successful preemptive intervention for infants showing early behavioral signs of autism on human services budgets is highly policy relevant.ObjectiveTo estimate the net cost impact of the iBASIS–Video Interaction to Promote Positive Parenting (iBASIS-VIPP) intervention on the Australian government.Design, Setting, and ParticipantsInfants (aged 12 months) showing early behavioral indicators of autism were recruited through community settings into the multicenter Australian iBASIS-VIPP randomized clinical trial (RCT), a 5- to 6-month preemptive parent-mediated intervention, between June 9, 2016, and March 30, 2018, and were followed up for 18 months to age 3 years. This economic evaluation, including cost analysis (intervention and cost consequences) and cost-effectiveness analyses of iBASIS-VIPP compared with usual care (treatment as usual [TAU]), modeled outcomes observed at age 3 through to 12 years (13th birthday) and was conducted from April 1, 2021, to January 30, 2023. Data analysis was conducted from July 1, 2021, to January 29, 2023.ExposuresiBASIS-VIPP intervention.Main Outcomes and MeasuresTo project the diagnostic trajectory and associated disability support costs drawing on the Australian National Disability Insurance Scheme (NDIS), the main outcome was the differential treatment cost of iBASIS-VIPP plus TAU vs TAU and disability-related government costs modeled to age 12 years, using a clinical diagnosis of ASD and developmental delay (with autism traits) at 3 years. Costs were calculated in Australian dollars and converted to US dollars. Economic performance was measured through the following: (1) differential net present value (NPV) cost (iBASIS-VIPP less TAU), (2) investment return (dollars saved for each dollar invested, taking a third-party payer perspective), (3) break-even age when treatment cost was offset by downstream cost savings, and (4) cost-effectiveness in terms of the differential treatment cost per differential ASD diagnosis at age 3 years. Alternate values of key parameters were modeled in 1-way and probabilistic sensitivity analysis, the latter identifying the likelihood of an NPV cost savings.ResultsOf the 103 infants enrolled in the iBASIS-VIPP RCT, 70 (68.0%) were boys. Follow-up data at age 3 years were available for 89 children who received TAU (44 [49.4%]) or iBASIS-VIPP (45 [50.6%]) and were included in this analysis. The estimated mean differential treatment cost was A $5131 (US $3607) per child  for iBASIS-VIPP less TAU. The best estimate of NPV cost savings was A $10 695 (US $7519) per child (discounted at 3% per annum). For each dollar invested in treatment, a savings of A $3.08 (US $3.08) was estimated; the break-even cost occurred at age 5.3 years (approximately 4 years after intervention delivery). The mean differential treatment cost per lower incident case of ASD was A $37 181 (US $26 138). We estimated that there was an 88.9% chance that iBASIS-VIPP would deliver a cost savings for the NDIS, the dominant third-party payer.Conclusions and RelevanceThe results of this study suggest that iBASIS-VIPP represents a likely good-value societal investment for supporting neurodivergent children. The estimated net cost savings were considered conservative, as they covered only third-party payer costs incurred by the NDIS and outcomes were modeled to just age 12 years. These findings further suggest that preemptive interventions may be a feasible, effective, and efficient new clinical pathway for ASD, reducing disability and the costs of support services. Long-term follow-up of children receiving preemptive intervention is needed to confirm the modeled results.

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