In the old paradigm, healthcare journals relied on "experts" (thought and content leaders) to write scholarly reviews on contemporary clinical issues of concern to the profession. Today, online data repositories have made "narrative reviews" more commonplace and enabled a wider group of authors, including professional organizations, to write "white papers," consensus documents, and best practice statements that include opinion-based manuscripts. Because of the influence of library sciences and medical informatics, the practices and principles of clinical reviews have become more structured, meaningful, medically useful, and evidence based1; they have evolved into a methodological and systematized process. Systematic reviews occupy the apex level of the evidence-based pyramid.2 Moving 5 layers down to the base of the pyramid are the following: randomized controlled trials, cohort studies, case-control studies, and case series/case reports; at the bottom of the evidence pyramid is expert opinion.2 Given the proliferation of information and databases to review, a systematized search with a focused research question, sound methodology, and specific exclusion and inclusion criteria is needed to validate the systematic review.3
For a review to earn the adjective "systematic,"4 it must be based on a clearly formulated question.4 In addition, the content of the report should include and justify relevant studies used with a systematic assessment of their quality. The fundamental difference that distinguishes systematic reviews from traditional narrative reviews and commentaries is that both the systematic review and the meta-analysis use a rigorous, explicit, and systematic approach and provide a cogent summary of the evidence.2-4 Consider the contemporary systematic review as a disciplined practice that locates, selects, and synthesizes the optimum primary studies that answer a single clinical question, for example, "What is the evidence for hypoperfusion of the skin leading to skin failure near the time of death."
The concept of narrowing and focusing the search question is important because of the heterogeneity of wound care patients and the complexity of their injuries and comorbidities. In deciding how to approach a systematic review of a given topic or clinical problem in wound care, the first principle is to taper the scope and focus.3,4 In this vein, I draw inspiration from the acumen of a medieval philosopher, William of Occam, who is attributed to the principle of Occam's razor: "One should not increase, beyond what is necessary, the number of entities required to explain anything."5 This maxim helps us to "shave off" those concepts, variables, or constructs that are not needed to explain the phenomenon. It will also reduce the chance of introducing inconsistencies, ambiguities, redundancies, and lack of discipline.5,6
There are 5 steps suggested in formulating a systematic review: (1) framing the questions for a review, (2) identifying the relevant work, (3) assessing the quality of studies, (4) summarizing the evidence, and (5) interpreting the findings.4,6 In contrast, the meta-analysis can be thought of as a systematic review that uses data from other studies.
The meta-analysis process is the statistical procedure for combining data from multiple studies. When the treatment effect (or effect size) is consistent from one study to the next, meta-analysis can be used to identify this common effect.6,7 On the other hand, when the effect varies from one study to the next, a meta-analysis should be used to determine the reason for the variation. Decisions about efficacy of an intervention or the validity of a hypothesis should not be based on the results of a singular study, because there are great inconsistencies in the results from one study to the next. Therefore, a mechanism is needed to synthesize the data across studies. Narrative reviews were used for this purpose, but the narrative review is mostly subjective and becomes impossibly difficult when more than a few studies are involved. Meta-analysis, by contrast, applies scientific formulas (much as one would use statistics to data within a single study), and can be used with any number of studies.7
In wound care, more systematic reviews are needed but may not be practical for the bedside clinician to conduct without training and resources. Wound care clinicians need the best evidence base to guide their clinical decision-making. With the proliferation of "big data" in science/medicine, the Cochrane clinical reviews, and the application of strength of evidence ratings, it is easier to teach students the art of finding evidence-based medicine to use at the point of care. Ideally, new trials would report their results in the context of previous relevant research, but this is rarely done. This leaves practitioners wishing to base decisions on evidence with the dilemma of using a single trial or disregarding evidence.
Over the last several decades, evidence-based medicine has become a cornerstone of medical literature analysis along with the strength of evidence ratings.
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