Mediation of 6-year mid-childhood follow-up outcomes after pre-school social communication (PACT) therapy for autistic children: randomised controlled trial

TY - JOUR

T1 - Mediation of 6-year mid-childhood follow-up outcomes after pre-school social communication (PACT) therapy for autistic children

T2 - randomised controlled trial

AU - Carruthers, Sophie

AU - Pickles, Andrew

AU - Charman, Tony

AU - McConachie, Helen

AU - Le Couteur, Ann

AU - Slonims, Vicky

AU - Howlin, Patricia

AU - Collum, Rachel

AU - Salomone, Erica

AU - Tobin, Hannah

AU - Gammer, Isobel

AU - Maxwell, Jessica

AU - Aldred, Catherine

AU - Parr, Jeremy

AU - Leadbitter, Kathy

AU - Green, Jonathan

N1 - Funding Information: The trial and follow‐up were sponsored by the University of Manchester and principally funded by MRC (G0401546, MR/K005863/1) with additional funding from the UK Department of Health and the National Institute for Health and Care Research (NIHR) through the Maudsley Biomedical Research Centre at the South London and Maudsley NHS Trust and King's College London and NIHR Senior Investigator funding to J.G. and A.P. (NIHR NF‐SI‐0617‐10168 and NF‐SI‐0617‐10120 respectively). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health. S.C. was supported by the MRC (MR/N013700/1). The authors gratefully thank all families who participated in the study and the referring professionals. The authors also acknowledge the fundamental contribution of the therapists who delivered the trial intervention and the large number of research assessors, acknowledged in previous papers, who generated the data on which this analysis is based. J.G. and C.A. receive Director's fees from a not‐for‐profit PACT training company IMPACT (CiC 10902031). T.C. has served as a paid consultant to F. Hoffmann‐La Roche Ltd. and Servier and has received royalties from Sage Publications and Guilford Publications. A.P. receives book and questionnaire royalties from WPS, OUP and Imperial College Press. The remaining authors have declared that they have no competing or potential conflict of interest. Key points Publisher Copyright: © 2023 The Authors. Journal of Child Psychology and Psychiatry published by John Wiley & Sons Ltd on behalf of Association for Child and Adolescent Mental Health.

PY - 2023/4/24

Y1 - 2023/4/24

N2 - Background: There are very few mechanistic studies of the long-term impact of psychosocial interventions in childhood. The parent-mediated Paediatric Autism Communication Therapy (PACT) RCT showed sustained effects on autistic child outcomes from pre-school to mid-childhood. We investigated the mechanism by which the PACT intervention achieved these effects. Methods: Of 152 children randomised to receive PACT or treatment as usual between 2 and 5 years of age, 121 (79.6%) were followed 5–6 years after the endpoint at a mean age of 10.5 years. Assessors, blind to the intervention group, measured Autism Diagnostic Observation Scale Calibrated Severity Score (ADOS CSS) for child autistic behaviours and Teacher Vineland (TVABS) for adaptive behaviour in school. Hypothesised mediators were child communication initiations with caregivers in a standard play observation (Dyadic Communication Measure for Autism, DCMA). Hypothesised moderators of mediation were baseline child non-verbal age equivalent scores (AE), communication and symbolic development (CSBS) and ‘insistence on sameness’ (IS). Structural equation modelling was used in a repeated measures mediation design. Results: Good model fits were obtained. The treatment effect on child dyadic initiation with the caregiver was sustained through the follow-up period. Increased child initiation at treatment midpoint mediated the majority (73%) of the treatment effect on follow-up ADOS CSS. A combination of partial mediation from midpoint child initiations and the direct effect of treatment also contributed to a near-significant total effect on follow-up TVABS. No moderation of this mediation was found for AE, CSBS or IS. Conclusions: Early sustained increase in an autistic child's communication initiation with their caregiver is largely responsible for the long-term effects from PACT therapy on autistic and adaptive behaviour outcomes. This supports the theoretical logic model of PACT therapy but also illuminates fundamental causal processes of social and adaptive development in autism over time: early social engagement in autism can be improved and this can have long-term generalised outcome effects.

AB - Background: There are very few mechanistic studies of the long-term impact of psychosocial interventions in childhood. The parent-mediated Paediatric Autism Communication Therapy (PACT) RCT showed sustained effects on autistic child outcomes from pre-school to mid-childhood. We investigated the mechanism by which the PACT intervention achieved these effects. Methods: Of 152 children randomised to receive PACT or treatment as usual between 2 and 5 years of age, 121 (79.6%) were followed 5–6 years after the endpoint at a mean age of 10.5 years. Assessors, blind to the intervention group, measured Autism Diagnostic Observation Scale Calibrated Severity Score (ADOS CSS) for child autistic behaviours and Teacher Vineland (TVABS) for adaptive behaviour in school. Hypothesised mediators were child communication initiations with caregivers in a standard play observation (Dyadic Communication Measure for Autism, DCMA). Hypothesised moderators of mediation were baseline child non-verbal age equivalent scores (AE), communication and symbolic development (CSBS) and ‘insistence on sameness’ (IS). Structural equation modelling was used in a repeated measures mediation design. Results: Good model fits were obtained. The treatment effect on child dyadic initiation with the caregiver was sustained through the follow-up period. Increased child initiation at treatment midpoint mediated the majority (73%) of the treatment effect on follow-up ADOS CSS. A combination of partial mediation from midpoint child initiations and the direct effect of treatment also contributed to a near-significant total effect on follow-up TVABS. No moderation of this mediation was found for AE, CSBS or IS. Conclusions: Early sustained increase in an autistic child's communication initiation with their caregiver is largely responsible for the long-term effects from PACT therapy on autistic and adaptive behaviour outcomes. This supports the theoretical logic model of PACT therapy but also illuminates fundamental causal processes of social and adaptive development in autism over time: early social engagement in autism can be improved and this can have long-term generalised outcome effects.

KW - Autism spectrum disorder

KW - developmental psychopathology

KW - early intervention

KW - mediation

KW - structural equation modelling

UR - http://www.scopus.com/inward/record.url?scp=85153623439&partnerID=8YFLogxK

U2 - 10.1111/jcpp.13798

DO - 10.1111/jcpp.13798

M3 - Article

AN - SCOPUS:85153623439

SN - 0021-9630

VL - 65

SP - 233

EP - 244

JO - Journal of child psychology and psychiatry

JF - Journal of child psychology and psychiatry

IS - 2

ER -