Identification of the Minimal Clinically Important Difference (MCID) for Childhood Autism Rating Scale Second Edition (CARS2) in children with ASD
- 1Boston University
Abstract
PurposeIn clinical trials, treatment efficacy is commonly assessed by comparing control and treatment groups. However, in large samples, even small and clinically trivial differences may achieve statistical significance. Accordingly, the Minimal Clinically Important Difference (MCID) is used as a threshold to determine whether statistically-significant effects are also clinically meaningful to patients. The objective of this study was to estimate the MCID for the Childhood Autism Rating Scale Second-Edition (CARS2) using the Patient Impression of Change (PIC) as an external anchor.
MethodsSingle-item PICs are not well suited to characterizing improvement in a multifaceted disorder such as ASD. Accordingly, the 77-item Autism Treatment Evaluation Checklist (ATEC) was used as a multi-item PIC. CARS2 and ATEC were administered concurrently to 62 children with ASD, aged 1.8-7.9 years, with assessments conducted six months apart.
ResultsThe correlation between changes in CARS2 and ATEC total scores was 0.41-0.44 (p<0.0001), supporting the use of ATEC as an anchor measure. Two anchor-based methods yielded MCIDs of 2.39-2.82 CARS2 points. Two distribution-based methods produced MCIDs of 1.33-3.32.
ConclusionsTaken together, these approaches suggest that a between-group difference of 2.6 CARS2 points (the midpoint of the anchor-based estimates) may serve as the MCID in children with ASD.
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BibTeX
@misc{vyshedskiy2026identification,
title = {{Identification of the Minimal Clinically Important Difference (MCID) for Childhood Autism Rating Scale Second Edition (CARS2) in children with ASD}},
author = {A. Vyshedskiy and L. E. Pavoski Poloni and A. Schmiedel Fucks and E. Khokhlovich and E. Fucks and A. Schmiedel},
howpublished = {medRxiv},
year = {2026},
month = aug,
doi = {10.64898/2026.08.31.26361823},
url = {https://www.medrxiv.org/content/10.64898/2026.08.31.26361823v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Identification of the Minimal Clinically Important Difference (MCID) for Childhood Autism Rating Scale Second Edition (CARS2) in children with ASD
AU - A. Vyshedskiy
AU - L. E. Pavoski Poloni
AU - A. Schmiedel Fucks
AU - E. Khokhlovich
AU - E. Fucks
AU - A. Schmiedel
PY - 2026
DA - 2026/08/31
PB - medRxiv
DO - 10.64898/2026.08.31.26361823
UR - https://www.medrxiv.org/content/10.64898/2026.08.31.26361823v1
AB - PurposeIn clinical trials, treatment efficacy is commonly assessed by comparing control and treatment groups. However, in large samples, even small and clinically trivial differences may achieve statistical significance. Accordingly, the Minimal Clinically Important Difference (MCID) is used as a threshold to determine whether statistically-significant effects are also clinically meaningful to patients. The objective of this study was to estimate the MCID for the Childhood Autism Rating Scale Second-Edition (CARS2) using the Patient Impression of Change (PIC) as an external anchor. MethodsSingle-item PICs are not well suited to characterizing improvement in a multifaceted disorder such as ASD. Accordingly, the 77-item Autism Treatment Evaluation Checklist (ATEC) was used as a multi-item PIC. CARS2 and ATEC were administered concurrently to 62 children with ASD, aged 1.8-7.9 years, with assessments conducted six months apart. ResultsThe correlation between changes in CARS2 and ATEC total scores was 0.41-0.44 (p<0.0001), supporting the use of ATEC as an anchor measure. Two anchor-based methods yielded MCIDs of 2.39-2.82 CARS2 points. Two distribution-based methods produced MCIDs of 1.33-3.32. ConclusionsTaken together, these approaches suggest that a between-group difference of 2.6 CARS2 points (the midpoint of the anchor-based estimates) may serve as the MCID in children with ASD.
ER -