Study design
Realist reviews are rooted in a critical realist philosophy and subscribe to a generative model of causality, meaning to deduce an outcome from a health system intervention, one must understand the mechanisms and contexts of the intervention as it is situated within its complex overarching structure [23, 24]. We will therefore synthesize not only the positive and negative outcomes of health system engagement, but also the underpinnings of these varied outcomes, thus uncovering the “why” and “how” of health outcomes that arise from an intervention.
We will use the key steps of a realist review identified by Pawson et al. [23] and informed by the Realist and Meta-narrative Evidence Syntheses: Evolving Standards (RAMESES) project [25, 26]. This iterative and non-linear approach includes (i) clarifying scope (i.e., identifying the purpose of the review and articulating key theories), (ii) searching for evidence, (iii) appraising the studies and extracting data, (iv) synthesizing evidence and drawing conclusions, and (v) disseminating, implementing, and evaluating recommendations [23] (see Additional file 1 for PRISMA-P diagram).
Clarifying scope
Early exploration, adjudication, and refinement of program theory offer a sketch of the terrain we wish to investigate (Fig. 1). Program theory describes how and why specific interventions are expected to work; in this case, it provides a broad explanatory model of how health system engagement (the “program”) is thought to achieve its impacts. Our team includes clinicians, academics, and PWUD. As a team, we identified and refined our questions of interest through iterative discussions. PWUD team members then described the possible contexts and mechanisms at play during health system engagement, and we complemented this discussion with a preliminary search of the literature for key theoretical and empirical publications that reflected this lived experience. Using these team discussions and literature sources we developed a draft visual representation of program theory through which to frame the subsequent steps of the review.
We anticipated that mechanisms within health system engagement activities would vary considerably depending on intersecting influences, and as such, we approached this review with no a priori hypothesis. However, consistent with realist review methods, we explored the potential explanatory role of candidate formal theories in describing our developing program theory [23, 27]:
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Resilience theory describes the process of transforming adversity into a growth, in particular by finding strength through situational, philosophical, relational, and ego-related constructs [28].
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Relationship-centered care emphasizes the relational aspects of care and the healing processes. In relationship with others, we identify and embody concepts which lead to the development of intrinsic motivation [29].
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Relational empowerment theory is a component of overall empowerment theory. It involves power being generated in the space of interpersonal exchanges. In addition, a component of relational-empowerment theory speaks to the confidence gained from solidarity in group membership, information sharing, and mutual obligation [30].
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Subjugated knowledge theory explores the relationship between power and knowledge. Foucault claims that some knowledges have been invalidated and that one can find power and health through reclaiming invalidated knowledge [31].
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Social movement theory explores the motivators of change, the framing of change messages, and to a lesser extent enhanced personal identity through aligning self with a larger social movement [32].
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Assumptive loss theory examines how trauma disorients and destabilizes one’s core beliefs and what interventions can be used to heal from this loss [33].
Realist review is an iterative process of engaging with the literature and the mechanics operating behind the apparent outcomes [34]. As such, we expect to further negotiate and potentially narrow our area of focus as priorities become apparent.
Searching for evidence
Realist reviews comprise complementary search strategies and several iterative yet progressive steps that are guided by emergent criteria eventually leading to a refinement of program theory [23, 35]. Consistent with iterative search strategies articulated by realist methods experts [35], we conducted an exploratory background search [23] using a single database (i.e., MEDLINE) to gain perspective on the literature, using search terms derived from the following:
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Population: people who use drugs (i.e., any unsanctioned use of opioids/stimulants/illegal substances, specifically excluding exclusive use of cannabis/alcohol/tobacco)
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Process: activities related to health system engagement in the form of planning, delivery, or research (i.e., health service planning, quality improvement, evaluation, research, collaborative advocacy, whether as an internal actor (e.g., front-line outreach/peer support/clinician) or an external actor (e.g., patient advisor), specifically excluding healthcare seeking or receiving as a patient/client
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Outcome: individual health and well-being (i.e., any personal physical/emotional/social/spiritual health impacts, specifically excluding collective/community health impacts)
We will use the articles retrieved in this first search to clarify the review scope, refine inclusion and exclusion criteria, and test potential theoretical fit [23, 35]. Two reviewers will test and refine document inclusion and exclusion criteria on initial search results until > 80% agreement is reached [36]. We will subsequently apply pre-specified search terms and modifiers, with assistance from a university librarian, and conduct a more in-depth search of multiple databases (i.e., MEDLINE, CINAHL, Embase, PsycINFO) to identify further articles meeting inclusion criteria.
Due to an expectation of potentially few search results, and the need to explore contextual factors, we will employ secondary cluster searching [37]. Cluster searching involves targeted searches and purposive sampling of key journals, including unpublished documents, and grey literature, and contacting authors and researchers for further information regarding a project. We may also search the non-PWUD literature to clarify emerging mechanisms of engagement as they play out for diverse populations and settings. By utilizing multiple search strategies, we will enhance the contextual richness of our findings and interpretation of the data.
Two reviewers will independently screen and select documents that fit our inclusion criteria and study objective, beginning with titles and abstracts and followed by full text review for selected abstracts. Where consensus cannot be achieved after discussion, a third reviewer will determine document eligibility. We will maintain a Covidence software-supported record of the screening process, including a rationale for inclusion and exclusion decisions [38]. To fully investigate program theory, we will not restrict by study type.
Appraising studies and extracting data
We will appraise each study based on its relevance (i.e., whether it addresses the theory under review) and its rigor (i.e., whether the inferences made within the study contribute to a test of its theory) in relation to our initial program theory and study objectives [23, 35]. Data appraisal will occur simultaneously but independently of data abstraction by two independent reviewers. Disagreements will be resolved through discussion and involvement of a third reviewer if necessary.
Selected articles will be independently extracted by two reviewers, using standardized data extraction forms and critical appraisal checklists adapted to study design [23, 39]. Data extraction will focus on context-mechanism outcome configurations relevant to our initial program theory—specifically, the context in which the engagement took place, its interaction with mechanism of actions as suggested by the authors or inferred from the study, and the impact on individual-level outcomes. Extracted information will include the study population and demographics, study type and method, study setting including country and community context, role of PWUD, recruitment and selection, training and support, reimbursement and incentives, and drop-out rates. We will engage in iterative discussion with all research team members, including PWUD with lived experience of health system engagement, to ensure consensus on extracted data. Though critical appraisal has limited value in realist reviews, this step is included to fully describe the literature; with the exception of major methodological flaws compromising a manuscript’s findings (wherein caution would be exercised in applying extracted configurations to program theory), the critical appraisal process will not otherwise influence the development of context-mechanism outcome configurations. Data saturation will be assessed after each round of extraction and we will stop searching when more literature is unlikely to add new knowledge to the review [23].
Synthesizing evidence and drawing conclusions
Using an iterative approach wherein researchers interact in an alternating fashion with the data and related theory (Fig. 2), we will synthesize abstracted context-mechanism outcome configuration data to identify demi-regularities (emerging patterns) and construct and refine an overarching context-mechanism-outcome framework for PWUD engagement, i.e., what engagement processes work (or do not work) for whom and in what circumstances, how they work, and what are the resulting individual-level outcomes [23]. We will use a variety of source types to refine and test theories, and support or refute inferences about mechanisms. We will actively seek “negative” or contradictory cases to examine the impact of intersecting contextual influences on the engagement process [40].
Disseminating, implementing, and evaluating recommendations
Dissemination and knowledge translation activities will include the development of best practice and evaluation recommendations for involving PWUD in health system activities, policy briefs, and scientific presentations and publications, as well as identification of key knowledge gaps. Findings from the review will be co-messaged by PWUD wherever feasible, using a variety of formats including information sessions hosted by community organizations, plain language summaries, infographics, and virtual presentations.
Team composition
We propose a participatory lens of key stakeholders to carry out the proposed review [15]. Academics, clinicians, students, and PWUD with lived experience of health system engagement will contribute to the work across all stages of the review, including refinement of review questions and purpose, development of the search strategy, selection of literature, data abstraction, analysis, and dissemination. Additionally, although Indigenous peoples are not the main focus of our study, a larger proportion of the PWUD community in Canada identify as Indigenous compared to the general population [41]. More than half of the PWUD members of the project team identify as Indigenous. Their presence will help to ensure that the study design, data collection, interpretation, and dissemination directly reflect the priorities of Indigenous and non-Indigenous PWUD alike and are conducted in a culturally safe manner [42].
We also recognize that any scholarship on PWUD requires close attention to researcher positionality and reflexivity. Researchers will reflect on their own identities and roles, consider how these influence data collection, analysis, and interpretation, and take measures to address potential personal and professional bias [43].
