Children, Youth, Families & Schools, Nebraska Center for Research on


Document Type


Date of this Version



Developmental Medicine & Child Neurology 63:1 (January 2021), 97–103.

doi: 10.1111/ dmcn.1470297


Copyright © 2020 Mac Keith Press. Published by Wiley. Used by permission.


Aim: To describe the development of an intervention-specific fidelity measure and its utilization and to determine whether the newly developed Sitting Together and Reaching to Play (START-Play) intervention was implemented as intended. Also, to quantify differences between START-Play and usual early intervention (uEI) services. Method: A fidelity measure for the START-Play intervention was developed for children with neuromotor disorders by: (1) identifying key intervention components, (2) establishing a measurement coding system, and (3) testing the reliability of instrument scores. After establishing acceptable interrater reliability, 103 intervention videos from the START-Play randomized controlled trial were coded and compared between the START-Play and uEI groups to measure five dimensions of START-Play fidelity, including adherence, dosage, quality of intervention, participant responsiveness, and program differentiation. Results: Fifteen fidelity variables out of 17 had good to excellent interrater reliability evidence with intraclass correlation coefficients (ICCs) ranging from 0.77 to 0.95. The START-Play therapists met the criteria for acceptable fidelity of the intervention (rates of START-Play key component use ≥ 0.8; quality ratings ≥ 3 [on a scale of 1–4]). The START-Play and uEI groups differed significantly in rates of START-Play key component use and quality ratings. Interpretation: The START-Play fidelity measure successfully quantified key components of the START-Play intervention, serving to differentiate START-Play from uEI.