Systematic reviews

Systematic reviews occupy the highest hierarchy in terms of quality of evidence and are a cornerstone of the evidence-based practice and policy movement.

Cochrane describes systematic reviews as:

“a high-level overview of primary research on a particular research question

high quality research evidence relevant to that question in order to answer it” (204).

Narrative reviews provide an overview of research methodologies, methods, findings, and interpretation within a research field by experts using their knowledge and experience which can introduce a high degree of bias (205). In contrast, a systematic review attempts to cover all known literature on the specific topic and details its design and methods explicitly for future quality assessment. Several organisations have been established to support systematic reviews in healthcare inclusive of the Cochrane Database of Systematic Reviews (CDSR), the University of York’s Centre for Reviews and Dissemination (CRD), and the Joanna Briggs Institute (JBI).

The CDSR is a database of primary research systematic reviews in healthcare and health policy provided by the Cochrane Collaboration which has been established for over 20 years (206). Cochrane Ireland supports activities of the Cochrane Collaboration in Ireland by providing training and support to ensure systematic reviews underpin policy, practice, and decision-making. The primary researcher undertook a two-day Cochrane Systematic Review course in Ireland prior to commencing phase one (Appendix 2.1).

The CRD was also established over 20 years ago and aims to provide evidence-based systematic reviews and meta-analysis of healthcare interventions via three databases: Database of Abstracts of Reviews of Effects (DARE); NHS Economic Evaluation Database (NHS EED); and Health Technology Assessment (HTA) Database. The systematic review protocol in phase one of this research was registered with the CRD (Appendix 3.1) and is available online (207).

The JBI collaborates with over 80 entities globally to promote and support the synthesis, transfer, and use of evidence through identifying effective healthcare practices to assist in the improvement of healthcare outcomes internationally (208). This includes translational science, synthesis science, implementation science, software for healthcare professionals, and promoting evidence-based practice. The JBI is affiliated with the Scottish Centre for Evidence-based Multi-professional Practice in Robert Gordon University (RGU) which includes training in conducting systematic reviews and promotion of implementation of findings

into practice (209). The primary researcher undertook training with JBI in RGU prior to commencing phase one (Appendix 2.1).

2.5.1 Scoping reviews

A fundamental step in the systematic review process is to comprehensively define the scope of the research aim. This requires consideration of existing literature, including gaps in the literature, clarification of definitions related to the research aim, and an understanding of how these are conceptualised within existing literature (210). An increasingly popular way to retrieve background information and obtain existing evidence is to conduct a scoping review, defined as a process of mapping the existing literature or evidence base (211). Scoping reviews are commonly used to clarify working definitions and conceptual boundaries of a field and are particularly useful for determining the value and probable scope of a full systematic review (212).

2.5.2 Overcoming challenges of systematic reviews in qualitative research

Qualitative research has been increasingly recognised as having a distinctive and important contribution in healthcare research as a means to explain processes and outcomes, and enhance the link between evidence and practice (213)(214).

Qualitative research can contribute to systematic reviews by (214)(215):

 informing reviews and ensuring reviews include appropriate studies to maximise relevance

 enhancing reviews by synthesising evidence

 extending reviews by undertaking a search to address research questions

 supplementing reviews by synthesising evidence within a stand-alone, but complementary, qualitative review to address research questions

Nonetheless, evidence-based practice, defined as “the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients....from systematic research” (216), strongly asserts that primary research based on RCTs is the most appropriate method to determine the effectiveness of interventions (217). Qualitative research has traditionally

about the scope of this evidence base, including the need to incorporate more qualitative research in clinical practice (218)(219). For example, only five qualitative studies out of 76 studies investigating potential barriers to guideline adherence were included in a systematic review by Cabana et al in 1999 (220) and no Cochrane review template is currently in place for qualitative evidence exclusively (214).

Much effort is now being invested into resolving the methodological and epistemological challenges associated with more inclusive forms of review, such as methodological prejudice, problems with searching for qualitative evidence, and issues with synthesising qualitative data (213)(221).

2.5.3 Narrative approaches to synthesis of qualitative evidence The synthesis of qualitative research is an area of debate and evolution (214).

In this research, a narrative synthesis of the systematic review was carried out to provide an analysis of included studies, and an overall assessment of the rigour of the evidence. Narrative synthesis relies primarily on the use of words and text to summarise and explain, or to ‘tell the story’, of findings of multiple studies (222).

Weaknesses of this type of synthesis include potential lack of transparency and clarity of methods employed (221) and formal guidance used on how to conduct such synthesis (223). Guidance from Popay et al (222) was applied to this systematic review which provides details on how narrative synthesis can be conducted in a more systematic and transparent way, focusing on implementation of interventions (Table 2.3).

Table 2.3: Tools and techniques for narrative synthesis adopted from Popay et al (222)

Element of synthesis Suggested tools and techniques Developing a preliminary

synthesis of findings

Textual description of studies, tabulation, transforming data into a common rubric, thematic and content analysis for translating data

Exploring relationships in the data

Subgroup analyses, idea webbing and conceptual mapping, qualitative case descriptions, investigator triangulation

Assessing robustness of synthesis

Weight of evidence, best evidence synthesis, validity assessment, reflecting critically on the synthesis process, checking the synthesis with authors of primary studies