5.1.1 Systematic reviews addressing textual evidence

The synthesis of textual evidence within the systematic review process is not well recognized in mainstream evidence-based practice and it is acknowledged that efforts to appraise and synthesize often conflicting opinions, narratives and policies are tentative. However, the use of a transparent systematic process to identify the best available textual evidence can provide practical guidance to practitioners and policy makers. “Textual evidence should be understood as the ... expression of clinical wisdom from health professionals” according to Jordan, Konno & Mu ^{1 (page 19)} but it may also draw on the expertise of consumers and of consumer representatives aligned with affiliated organizations.  Textual evidence, in the form of narrative accounts, expert opinion papers or policy documents, has a role to play in evidence-based health care and can be used to either complement empirical evidence or stand alone as the best available evidence (either in the absence of research studies; or when the question itself is best addressed by systematically reviewing non-research derived evidence).

As evidence-based healthcare focuses on the need to use interventions that are supported by the most up-to-date evidence or knowledge, it is appropriate to consider clinicians’ tacit knowledge derived from their clinical experiences or the dominant healthcare discourse at the time of practice as a source of evidence. This is drawn from the extensive work of Patricia Benner who explored clinical wisdom and nursing practice.^2-5  Diverse knowledge/evidence types are required to inform practice, and for this reason comprehensive systematic review methods have been formulated to explore not only the evidence on the effectiveness of interventions (‘knowing what’ type of evidence), but also evidence related to subjective human experiences, culture, values, ethics, health policy, or the accepted discourse at the time of practice (‘knowing how’ type of evidence).^2-5

Textual evidence often represents the best available evidence where formal research on the specific topic is limited or non-existent.  When a particular problem or question is only answered through the perspectives of clinical experience or the consensus of experts (either clinicians or citizens), this evidence becomes vital to practitioners and policy makers and represents the best available evidence to guide their decision-making. Some refer to this as expert evidence. ^6,7 This type of evidence can be used to complement empirical evidence or, in the absence of formal research studies, may stand alone as the best available evidence.

Systematic reviews of textual evidence require reviewers to consider the validity of textual data as a source of guidance for practice or policy; to identify and extract the conclusions or recommendations made (messages conveyed) from papers or documents included in the review; and to synthesize these messages into indicative statements that can be used to inform policy and practice. The theoretical basis to the JBI approach to systematic reviews of textual evidence is further outlined in this chapter.