Scoping reviews are exploratory projects that systematically map the literature on a topic, identifying key concepts, theories and sources of evidence. Scoping reviews are often conducted before full syntheses, and undertaken when feasibility of the research is considered to be a challenge, either because the relevant literature is thought to be vast and diverse (varying by methods, theoretical orientations and disciplines) and/or it is thought that little literature exists. In the scoping review, the same systematic, rigorous methodologies used by the systematic review are used to find studies and extract data. Analyses and syntheses are part of every scoping review but the depth and type of analysis are different.
A scoping review (also scoping study) usually refers to a rapid gathering of literature in a given policy of clinical area where the aims are to accumulate as much evidence as possible and map the results. Scoping reviews provide an overview of the type, extent and quantity of research available on a given topic. By ‘mapping’ existing research, a scoping review can identify potential research gaps and future research needs, and do so by using systematic and transparent methods.
In 2005, Arksey and O’Malley published the first methodological framework for conducting scoping studies. The term ‘scoping review’ does not seem to have a commonly-accepted definition but several researchers have attempted definitions. Scoping reviews can be an efficient way of indentifying themes and trends in high-volume areas of scientific enquiry. Generally, a scoping review is an interactive process whereby existing literatures identified, examined and conceptually mapped, and where gaps are identified. Thus, a scoping review could be considered as a first step in doing a systematic review or large study.
In simple words, researchers can undertake a scoping study to examine the extent, range, and nature of research activity, determine the value of undertaking a full systematic review, summarize and disseminate research findings, in addition to identifying the gaps in the existing literature. As such, researchers can use scoping studies to clarify a complex concept and refine subsequent research inquiries. Scoping studies may be particularly relevant to disciplines with emerging evidence, such as rehabilitation science, in which the paucity of randomized controlled trials makes it difficult for researchers to undertake systematic reviews. In these situations, scoping studies are ideal because researchers can incorporate a range of study designs in both published and grey literature, address questions beyond those related to intervention effectiveness, and generate findings that can complement the findings of clinical trials.
The literature search in a scoping review should be as extensive as possible, and include a range of relevant databases, hand searches and attempts to identify unpublished literature. Often, the underlying aim of a scoping review is to explore the literature as opposed to answering specific questions. The scoping review should also include locating organizations and individuals that are relevant to the domain and what those groups have published. In the social sciences, scoping studies are performed at an initial stage of doing research (i.e. program, project, process, or grant). Scoping reviews are used in some research areas to justify further investigation, time and resources.
In evidence-based practice, scoping studies are undertaken as distinct research projects, and as precursors to other types of research. However, a scoping study may be requested as a search prior to the systematic review or preparatory to costing research projects. The interpretation, methodology and expectations of scoping reviews are variable and suggest that conceptually, scoping is not well-understood or defined. The distinction between scoping as an integral preliminary process in the development of a research proposal or a formative, methodologically rigorous activity in its own right has not been examined. Scoping studies in medicine are slowly evolving; their strength lies in their ability to summarize a body of evidence for quick but accurate synthesis. As with other approaches to evidence synthesis a standardized approach is always welcome. Full literature searching aimed at retrieving a maximum number of relevant studies or articles in a given discipline starts with a scope of a topic.