Guidance for intervention fidelity in non-drug, non-surgical trials: a scoping review

Fernando Sousa; Mengda Zhu; Melanie K Farlie; Terry Haines; Belinda Borrelli; Christopher Carroll; Catherine Mathews; Daniel C Ribeiro; Julie M Fritz; Martin Underwood; Nadine E Foster; Sarah E Lamb; Zila M Sanchez; Peter Malliaras

doi:10.1016/j.jclinepi.2025.111868

Guidance for intervention fidelity in non-drug, non-surgical trials: a scoping review

J Clin Epidemiol. 2025 Jun 13:111868. doi: 10.1016/j.jclinepi.2025.111868. Online ahead of print.

Authors

Affiliations

¹ School of Primary and Allied Health Care, Monash University, Melbourne, Australia. Electronic address: fernando.sousa@monash.edu.
² School of Primary and Allied Health Care, Monash University, Melbourne, Australia.
³ Center for Behavioral Science Research, Department of Health Policy and Health Services Research, Boston University, Henry M. Goldman School of Dental Medicine, Boston, MA, USA.
⁴ Division of Population Health, University of Sheffield, Sheffield, UK.
⁵ Health Systems Research Unit, South African Medical Research Council, Cape Town, South Africa; School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
⁶ Curtin School of Allied Health, Faculty of Health Sciences, Curtin University, Perth, WA, Australia.
⁷ Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, UT, USA.
⁸ Warwick Clinical Trials Unit, University of Warwick, Warwick, UK; University Hospitals of Coventry and Warwickshire, Coventry, UK.
⁹ STARS Education and Research Alliance, Surgical Treatment and Rehabilitation Service (STARS), The University of Queensland and Metro North Health, Brisbane, Australia.
¹⁰ University of Exeter, St Luke's Campus, Exeter, UK.
¹¹ Department of Preventive Medicine, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, Brazil.

PMID: 40517847
DOI: 10.1016/j.jclinepi.2025.111868

Abstract

Objective: Intervention fidelity is poorly reported in trials of non-drug, non-surgical interventions. We aimed to review existing intervention fidelity guidance documents, assess their development methods, and synthesise their terminology, definitions, domains, and recommendations.

Study design: We searched six databases from inception to September/2023 to identify documents describing explicit, actionable, and overarching recommendations on intervention fidelity. We supplemented this with backward citation searching in April/2024. Two reviewers independently screened titles, abstracts, and full texts. We conducted a qualitative content analysis, following JBI guidance, to extract and synthesise data on document characteristics, scope, methods, terminology, definitions, domains, and recommendations.

Results: After screening 7,142 records from databases searches and 1,768 from citation searching, we included 73 documents. Most documents were unclear about the core methods used to develop recommendations (67/73, 92%), and only one document explicitly reported using consensus (1/73, 1%). We identified definitions of intervention fidelity across six categories and seven intervention fidelity domain categories. Of these, only two ('provider delivery-related aspects' and 'participant involvement-related aspects') were reported in most documents (>50%). We identified 81 recommendations across 10 categories, with only 14 being reported across more than half of the documents.

Conclusion: Existing documents providing recommendations on intervention fidelity reflect the evolving nature of the field, with consensus still needed on several aspects. The gaps and inconsistencies identified in this review emphasise the need for clearer, more systematic, and globally applicable guidelines. These findings will inform the development of ReFiND, an international, consensus-based reporting guideline for intervention fidelity in non-drug, non-surgical trials.

Keywords: Clinical Trials as Topic; Evaluation Studies as Topic; Health Plan Implementation; Methods; Research Design; Research Report.