Does Treatment Fidelity of the Early Start Denver Model Impact Skill Acquisition in Young Children with Autism?

Zitter et al. (2023) ran a randomized trial in general-education classrooms. They tested whether doing CPRT with high fidelity helps autistic students learn more. Teachers got training and then delivered the lessons. The team tracked how closely staff followed the steps and how much kids learned.

Higher fidelity led to bigger learning gains. Students whose teachers stuck to the CPRT script showed more growth. The training also cut approach-withdrawal problems and lifted engagement compared with the wait-list group.

The result lines up with McMiezah et al. (2020), who saw positive vocal turns after six months of home-based PRT. It also echoes Biggs et al. (2026), where LEGO therapy reached high fidelity in 98 schools, proving classroom staff can hit the mark when they are trained well.

Yet Burrows et al. (2018) seems to disagree. Their preschool classroom trial found no social-communication boost after the ASAP program. The gap is about age and focus. ASAP targeted only preschool play skills and found nothing. CPRT covered broader classroom learning and found clear gains.

Ventola et al. (2014) came first, showing short PRT can help social skills in small cases. Zitter moves the same idea into real classrooms and ties the gains to fidelity, updating the story.

You now have hard evidence that every extra fidelity point pays off in student learning. Run a quick fidelity check during your next CPRT session. If you spot drift, pause and re-model the step. Five minutes of correction now can save weeks of re-teaching later.