Scoping reviews

Systematic reviews and meta-analyses are important studies that can help avoid research waste by synthesising existing evidence, from randomised controlled trials for example, before embarking on new and expensive studies [1]. However many systematic reviews fail to identify sufficient high quality studies to include and therefore effectiveness of an intervention cannot be established. These are often conducted in areas where a condition is prevalent. Systematic reviews with and without meta-analyses are published in most issues of Physiotherapy (e.g. Refs. [2, 3]). Where the evidence is largely qualitative, an alternative review methodology is required which combines and summarises various qualitative sources. The qualitative meta-synthesis is a process whereby the researchers can select, appraise, summarize, and combine qualitative evidence to address a research question (e.g. Ref [4].).

More recently, we have seen the emergence of systematic scoping reviews as a formal method of assessing the state of the art in an area where perhaps there are insufficient high quality studies. They allow knowledge synthesis, the purpose of which is to characterise the literature in an area of interest and therefore identify gaps in the current evidence or the value of a full systematic review [5].

A scoping review follows a systematic approach which maps evidence, theories, concepts and sources. These reviews have emerged over the past decade and are becoming an increasingly common approach for mapping broad topics. However, early scoping reviews lacked methodological standardisation and rigour and it was recognised that to be reliable and provide valid evidence, that more stringent guidelines were required [6]. Using knowledge and implementing results can be complex and requires time, skill in searching and evaluating research evidence and having the authority to implement findings [7]. However, it has been reported that both the use of guidelines and methodological transparency increases research uptake [8]. Recognition that the methodological and reporting quality of scoping reviews needed improvement led to the development of guidelines for conducting scoping reviews; The Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for Scoping Reviews (PRISMA-ScR) is available on the EQUATOR website [8]. The checklist consists of 20 essential reporting items and two optional items. A helpful introductory video and a series of tip sheets for reporting each PRISMA-ScR item can be found here. 

Two recent scoping reviews published in Physiotherapy demonstrate the relevance of this methodology to the profession; these are in the areas of the use of thoracic ultrasound by physiotherapists [9] and interventions for people with dementia and hip fracture [10].

Whilst the limitations of scoping reviews are acknowledged [11, 12] as with all research, transparency is key. Provided the scope, rigour and limitations are clearly acknowledged, then the reader can determine the reliance they can place on the results. Scoping reviews may enable researchers to determine whether sufficient robust research exists, and to define a research question that a systematic review can address.

When embarking on an exercise to accumulate information, Table 1 highlights issues to consider when deciding whether to conduct a systematic review or a scoping review.

Scoping reviews