Systematic review

Systematic reviews are a type of literature review that uses systematic methods to collect secondary data, critically appraise research studies, and synthesize findings qualitatively or quantitatively. Systematic reviews formulate research questions that are broad or narrow in scope, and identify and synthesize studies that directly relate to the systematic review question. They are designed to provide a complete, exhaustive summary of current evidence relevant to a research question. For example, systematic reviews of randomized controlled trials are key to the practice of evidence-based medicine, and a review of existing studies is often quicker and cheaper than embarking on a new study. Systematic reviews are a type of literature review that uses systematic methods to collect secondary data, critically appraise research studies, and synthesize findings qualitatively or quantitatively. Systematic reviews formulate research questions that are broad or narrow in scope, and identify and synthesize studies that directly relate to the systematic review question. They are designed to provide a complete, exhaustive summary of current evidence relevant to a research question. For example, systematic reviews of randomized controlled trials are key to the practice of evidence-based medicine, and a review of existing studies is often quicker and cheaper than embarking on a new study. While systematic reviews are often applied in the biomedical or healthcare context, they can be used in other areas where an assessment of a precisely defined subject would be helpful. Systematic reviews may examine clinical tests, public health interventions, environmental interventions, social interventions, adverse effects, and economic evaluations. An understanding of systematic reviews and how to implement them in practice is highly recommended for professionals involved in the delivery of health care, public health and public policy. A systematic review aims to provide a complete, exhaustive summary of current literature relevant to a research question. The first step in conducting a systematic review is to create a structured question to guide the review. The second step is to perform a thorough search of the literature for relevant papers. The Methodology section of a systematic review will list all of the databases and citation indexes that were searched such as Web of Science, Embase, and PubMed and any individual journals that were searched. The searching of different databases is a hallmark of clinical trials. In this regard, more recently there has been increased recognition of the importance of using different search technologies, with artificial intelligence-based tools gaining recognition. The titles and abstracts of identified articles are checked against pre-determined criteria for eligibility and relevance to form an inclusion set. This set will relate back to the research problem. Each included study may be assigned an objective assessment of methodological quality preferably by using methods conforming to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement (the current guideline) or the high quality standards of Cochrane. Systematic reviews often, but not always, use statistical techniques (meta-analysis) to combine results of eligible studies, or at least use scoring of the levels of evidence depending on the methodology used. An additional rater may be consulted to resolve any scoring differences between raters. Systematic review is often applied in the biomedical or healthcare context, but it can be applied in any field of research. Groups like the Campbell Collaboration are promoting the use of systematic reviews in policy-making beyond just healthcare. A systematic review uses an objective and transparent approach for research synthesis, with the aim of minimizing bias. While many systematic reviews are based on an explicit quantitative meta-analysis of available data, there are also qualitative reviews which adhere to standards for gathering, analyzing and reporting evidence. The EPPI-Centre has been influential in developing methods for combining both qualitative and quantitative research in systematic reviews. The PRISMA statement suggests a standardized way to ensure a transparent and complete reporting of systematic reviews, and is now required for this kind of research by more than 170 medical journals worldwide. Developments in systematic reviews during the 21st century included realist reviews and the meta-narrative approach, both of which addressed problems of methods and heterogeneity existing on some subjects. Scoping reviews are distinct from systematic reviews in a number of important ways. A scoping review is an attempt to search for concepts, mapping the language which surrounds those and adjusting the search method iteratively. A scoping review may often be a preliminary stage before a systematic review, which 'scopes' out an area of inquiry and maps the language and key concepts. As it is a kind of review which should be systematically conducted (the method is repeatable), some academic publishers categorize them as a kind of 'systematic review', which may cause confusion. Scoping reviews are helpful when it is not possible to carry out a systematic synthesis of research findings, for example, when there are no published clinical trials in the area of inquiry. Scoping reviews are a helpful method when an area of inquiry is very broad, for example, exploring how the public are involved in all stages systematic reviews. There is still a lack of clarity when defining the exact method of scoping review as it is both an iterative process and is still relatively new and there have been a number of attempts to improve the standardisation of the method. PROSPERO does not permit the submission of protocols of scoping reviews, although some journals will publish protocols for scoping reviews.