Monitoring Intervention Fidelity and Adaptations

Section 1



Leah Tuzzio, MPH

Eric Larson, MD, MPH

James Fraser

Russell Glasgow, PhD


Contributing Editor

Liz Wing, MA

A primary goal of conducting embedded PCTs (ePCTs) is to contribute high-quality evidence needed to establish and sustain a learning healthcare system. Embedded PCTs by nature are conducted in dynamic, complex healthcare delivery settings where unanticipated events and changes will happen. In addition to the importance of designing ePCT interventions with implementation in mind, it is likewise essential to monitor both planned and unplanned changes to the intervention during the trial’s execution phase. Evaluating such changes will help inform whether the intervention was successful or not. It may also be useful in the implementation, dissemination, and sustainability of an effective intervention, or at least its core functions, within the health system (Denis et al. 2002).

Interventions that are more pragmatic on the PRECIS-2 spectrum deliberately build in flexibility to the intervention’s components, delivery, and adherence in order to be “fit for purpose” (Louden et al. 2015; Norton et al. 2019). Researchers should expect health systems to make slight adjustments so that the intervention fits within clinical workflow and care provision, and to minimize additional work and burden. And researchers should plan for course corrections in order to promote effectiveness of trial implementation and sustainability in the real-world contexts in which they are set. Consistent monitoring and reporting of intervention adaptations will also be needed to assess fidelity to the intervention’s design and analysis and to determine whether the adaptation had an impact—positive or negative—on the effectiveness or reproducibility of the intervention and potentially on the findings (Wiltsey Stirman et al. 2019).

In this chapter, we describe different types of changes a study team may encounter while conducting an ePCT. We also introduce strategies that teams can use to anticipate, monitor, and document adaptations to their intervention to support study analysis and sustainability, and to set the stage for dissemination and implementation of successful interventions in other healthcare settings.




Denis JL, Hebert Y, Langley A, Lozeau D, Trottier LH. 2002. Explaining diffusion patterns for complex health care innovations. Health Care Manage Rev. 27:60-73. PMID: 12146784.

Loudon K, Treweek S, Sullivan F, Donnan P, Thorpe KE, Zwarenstein M. 2015. The PRECIS-2 tool: designing trials that are fit for purpose. BMJ. 350:h2147. doi:10.1136/bmj.h2147. PMID: 25956159.

Norton WE, Zwarenstein M, Czajkowski S, et al. 2019. Building internal capacity in pragmatic trials: a workshop for program scientists at the US National Cancer Institute. Trials. 20:779. doi:10.1186/s13063-019-3934-y.

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Wiltsey Stirman S, Baumann AA, Miller CJ. 2019. The FRAME: an expanded framework for reporting adaptations and modifications to evidence-based interventions. Implement Sci. 14:58. doi:10.1186/s13012-019-0898-y. PMID: 31171014.

Version History

Published March 2020


Monitoring Intervention Fidelity and Adaptations: Introduction. In: Rethinking Clinical Trials: A Living Textbook of Pragmatic Clinical Trials. Bethesda, MD: NIH Health Care Systems Research Collaboratory. Available at: Updated March 27, 2020.