The synthesis of evidence in the form of the systematic review is at the center of evidence-based practice (Pearson et al. 2005).

Systematic reviews traditionally bring together evidence from quantitative literature to answer questions on the effectiveness of a specific intervention for a particular condition. Beyond effectiveness, JBI is also interested in the context of care delivery, its cost-effectiveness, as well as patient, carer and healthcare provider preferences. These foci are explored in terms of the appropriateness, meaningfulness, and feasibility of healthcare practices and delivery. These sorts of questions are most commonly answered by consideration of other forms of primary evidence found in qualitative and economic research studies. The results of well-designed research studies of any methodology are regarded by JBI as potential sources of credible evidence to inform healthcare practice and policy. To match this broader and more inclusive view of evidence, JBI has developed a number of methodologies and methods for the synthesis of evidence to support healthcare decision-making for a number of review types (Munn et al. 2018b).

All JBI knowledge syntheses – including scoping reviews – begin with the development of an a priori protocol with inclusion and exclusion criteria that relate clearly to the review question/s. A typical systematic review aims to answer a specific question (or series of questions) based on very precise inclusion criteria, for example, a systematic review may pose the following precise question based upon the PICO (Population, Intervention, Comparator, and Outcome) elements of its inclusion criteria (Marshall-Webb et al. 2018):

What is the effectiveness of Nissen fundoplication in comparison to anterior partial fundoplication (90 degree, 120 degree and 180 degree) and posterior 270 degree fundoplication in terms of symptom control of gastro-esophageal reflux disease, and what are the side effects of these surgical interventions?


It is clear from this question that only certain types of experimental evidence and data would be relevant and that the review will be very specific in terms of the population, intervention, comparator and outcomes against which it will determine effectiveness.

A scoping review will have a broader “scope” with correspondingly less restrictive inclusion criteria. The following question based upon the PCC (Population, Concept and Context; see Section 11.2) elements of the inclusion criteria may be posed (Kao et al. 2017a):

 “What quality of life questionnaires are available for pediatric patients following tonsillectomies with or without adenoidectomies for chronic infections or sleep disordered breathing?”


The ‘population’ in this question is clearly specified (pediatric patients who have had tonsillectomies with or without adenoidectomies). The ‘concept’ in this example is also clear; the questionaries used to assess quality of life for pediatric patients after a tonsillectomy performed for the purposes of treating either chronic infection or sleep disordered breathing. While not explicit, the ‘context’ in this case is quite ‘open’ in the sense that the quality of life instrument may be used in any setting (primary health care, acute care, or even specialist psychological care or counselling).

An especially important point is that the scoping review may draw upon data from any source of evidence and research methodology, and is not restricted to quantitative studies (or any other study design) alone. This however is not prescriptive; reviewers may decide that particular study designs are beyond the scope of their review or not be appropriate or useful for consideration. For example, the protocol of the above example scoping review specifies that while any type of quantitative study design may be eligible for inclusion, as only psychometrically validated quantitative questionnaires were sought, qualitative and gray literature was not considered for inclusion;    In this example however, reports from published randomized controlled trials were considered side by side with observational studies (Kao et al. 2017a). Because of the broad nature of scoping review questions, they are particularly useful for bringing together evidence from disparate or heterogeneous sources.


It is important to highlight the distinction between scoping reviews and “mixed methods” systematic reviews that also rely on evidence from different study designs (Lizarondo et al. 2017). While the aim of a scoping review is to determine what kind of evidence (quantitative and/or qualitative etc.) is available on the topic and to represent this evidence by mapping or charting the data, mixed methods systematic reviews are designed to answer a question or questions based on the synthesis of evidence from for example qualitative, and quantitative research.

When contrasting systematic reviews, scoping reviews and traditional literature reviews, the following table (Table 11.1) from Munn et al. 2018 may be useful (as are the comparisons available in Tricco 2018):

Table 11.1: Defining characteristics of traditional literature reviews, scoping reviews and systematic reviews


Traditional Literature Reviews

Scoping reviews

Systematic reviews

A priori review protocol

No

Yes (some)

Yes

PROSPERO registration of the review protocol

No

No*

Yes

Explicit, transparent, peer reviewed search strategy

No

Yes

Yes

Standardized data extraction forms

No

Yes

Yes

Mandatory Critical Appraisal (Risk of Bias Assessment)

No

No**

Yes

Synthesis of findings from individual studies and the generation of ‘summary’ findings***

No

No

Yes


*Current situation; this may change in time, and we suggest registration/publication of scoping review protocols is critical. Examples of databases where scoping reviews may be registered are: is “Open Science Framework   (https://osf.io/) ” and “Figshare (https://figshare.com/). **Critical appraisal is not mandatory, however, reviewers may decide to assess and report the risk of bias in scoping reviews depending on the purpose of the review. ***The use of statistical meta-analysis (for effectiveness, prevalence or incidence, diagnostic accuracy, aetiology or risk, prognostic or psychometric data), or meta-synthesis (experiential or expert opinion data) or both in mixed methods reviews is typically not conducted in a scoping review.

While recommendations or implications for research, including for primary research, other scoping reviews, or systematic reviews, may be generated from the results of a scoping review – especially those conducted with the objective of being precursors to systematic reviews (Anderson et al. 2008). Recommendations for practice are difficult due to the fact that a formal assessment of methodological quality of the included sources of evidence of a scoping review is generally not performed. In addition, a formal synthesis is not normally conducted in a scoping review (at least not in the same way for systematic reviews) and as such the methodology is not naturally aligned to establishing practice or policy recommendations. However, if recommendations for practice or policy are developed, it is expected that they will clearly flow from the objectives of the scoping review (Munn et al. 2018 a, b).





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