A Novel Method for Assessing Design Fidelity in Web-Based Behavioral Interventions

Jeffrey Lambert, Lewis Elliott, Adrian Taylor, Paul Farrand, Anne Haase, Colin Greaves

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Objective: Delivery is one of the most common ways of assessing fidelity in behavioral interventions.
However, there is a lack of research reporting on how well an intervention protocol reflects its proposed
theoretical principles (design fidelity). This study presents a systematic method for assessing design
fidelity and applies it to the eMotion web-based intervention targeting physical activity and depression.
Method: The eMotion intervention comprises of 13 web-based modules, designed according to an
underlying intervention map. An independent rater with expertise in behavior change coded the presence
or absence of behavior change techniques (BCTs) in the content of eMotion. Results of coding were
compared to the intervention designers’ a priori specification for interrater reliability. Results: After
discussion, the independent rater and the intervention designer had a high agreement for the presence of
BCTs relating to behavioral activation (AC1 0.91) with “demonstration of behavior” and “monitoring
of emotional consequences” having the lowest agreement (AC1 0.4). There was also high agreement
for the presence of BCTs targeting physical activity (AC1 0.88) with “demonstration of behavior” and
“monitoring of emotional consequences” having the lowest agreement (AC1 0.4). The eMotion
description was then amended to align the interrater agreement. Conclusions: This study presents a novel
method for assessing design fidelity. Developers of behavioral (and other multicomponent) interventions
are encouraged to develop and refine this method and assess design fidelity in future interventions to
ensure BCTs are operationalized as intended.
Original languageEnglish
Pages (from-to)217-225
Number of pages9
JournalHealth Psychology
Issue number3
Publication statusPublished - 31 Mar 2021

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