A literature review provides an overview of a topic, and is something most of you have encountered at one time or another. It is usually an article, or a section of an article,* that compiles and summarizes published materials (books, articles, etc.) which provide an examination of recent or current literature on a chosen topic.
Review articles can cover a wide range of subject matter at various levels of completeness and comprehensiveness based on analyses of literature that may include research findings. The review may reflect the state of the art. It also includes reviews as a literary form.
As a publication type, it is an article or book published after examination of previously published material on a subject. It may be comprehensive to various degrees, and the time range of material scrutinized may be broad or narrow, although the reviews most often desired are reviews of the current literature. The textual material examined may be equally broad and can encompass, in medicine specifically, clinical material as well as experimental research or case reports.
State-of-the-art reviews tend to address more current matters. A review of the literature must be differentiated from a HISTORICAL ARTICLE on the same subject, but a review of historical literature is also within the scope of this publication type.
*Lit reviews aren't always obviously labeled "literature review"; they may be embedded within sections such as the introduction or background.
A systematic review attempts to collate all empirical evidence that fits pre-specified eligibility criteria in order to answer a specific research question. It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made (Antman 1992, Oxman 1993).
The key characteristics of a systematic review are:
From Cochrane Handbook, 1.2.2
Many, but not all, systematic reviews contain meta-analyses. Meta-analysis is the use of statistical methods to summarise the results of independent studies. By combining information from all relevant studies, meta-analyses can provide more precise estimates of the effects of health care than those derived from the individual studies included within a review. Meta-analyses also facilitate investigations of the consistency of evidence across studies, and the exploration of differences across studies (Cochrane Handbook, 1.2.2). More information on meta-analyses can be found in Cochrane Handbook, Chapter 9.
A meta-analysis goes beyond critique and integration and conducts secondary statistical analyses on the outcomes of similar studies. It is a systematic review that uses quantitative methods to synthesize and summarize the results.
An advantage of a meta-analysis is the ability to be completely objective in evaluating research findings. Not all topics, however, have sufficient research evidence to allow a meta-analysis to be conducted. In that case, an integrative review is an appropriate strategy.
An integrative review summarizes past research and draws overall conclusions from the body of literature on a particular topic. The body of literature comprises all studies that address related or identical hypotheses. In a properly executed integrative review, the effects of subjectivity are minimized through carefully applied criteria for evaluation. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor and replication.
"In general, scoping reviews are commonly used for ‘reconnaissance’ – to clarify working definitions and conceptual boundaries of a topic or field. Scoping reviews are therefore particularly useful when a body of literature has not yet been comprehensively reviewed, or exhibits a complex or heterogeneous nature not amenable to a more precise systematic review of the evidence. While scoping reviews may be conducted to determine the value and probable scope of a full systematic review, they may also be undertaken as exercises in and of themselves to summarize and disseminate research findings, to identify research gaps, and to make recommendations for the future research."
From Peters, MD, Godfrey, CM, Khalil, H, McInerney, P, Parker, D & Soares, CB 2015, 'Guidance for conducting systematic scoping reviews', International Journal of Evidence-Based Healthcare, vol. 13, no. 3, pp. 141-146:
A rapid review is an assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research. "Rapid reviews have emerged as a streamlined approach to synthesizing evidence in a timely manner -typically for the purpose of informing emergent decisions faced by decision makers in health care settings."
An umbrella review is a synthesis of existing reviews, only including the highest level of evidence such as systematic reviews and meta-analyes. It specifically refers to review compiling evidence from multiple reviews into one accessible and usable document. Umbrella reviews focuses on broad condition or problem for which there are competing interventions and highlights reviews that address these interventions and their result.
Methodology paper: Aromataris, E, Fernandez, R, Godfrey, CM, Holly, C, Khalil, H & Tungpunkom, P 2015, 'Summarizing systematic reviews: Methodological development, conduct and reporting of an umbrella review approach', Int J Evid Based Healthc, vol. 13, no. 3, pp. 132-140
A systematized review attempts to include elements of the systematic review process while stopping short of the systematic review. Systematized reviews are typically conducted as a postgraduate student assignment, in recognition that they are not able to draw upon the resources required for a full systematic review (such as two reviewers).
Special Thanks to Dr. Julie Sarpy, PhD, MSLS, MA, AHIP, for permission to reuse content from her Medical Sciences guide. Dr. Sarpy is a Reference and Instruction Librarian at the Martin and Gail Press Health Professions Division Library, and a Liaison to the Dr. Kiran C. Patel College of Allopathic Medicine, as well as an Adjunct Assistant Professor with the Department of Medical Education at the Dr. Kiran C. Patel College of Osteopathic Medicine at Nova Southeastern University in Ft. Lauderdale, Florida.