When you have completed this chapter, you will be able to understand:
What review of literature is and what its purpose is
How literature review is carried out
What evidence-based clinical practice is and what its challenges are
How to track the best evidence for the right answers
The hierarchy of clinical evidence of different studies
The different types of secondary research studies
How to carry out a literature search and compile the review material
In previous chapters we discussed the various steps in undertaking a research, followed by description of the different types of studies to answer different research objectives. The accumulated research output is meant to support the researcher in knowing the gaps in knowledge and carry out further research in those areas. Likewise, for health care professionals, it serves as a source of evidence for better clinical decision making. Researchers and clinicians should be able to both access and critically review the accumulated scientific literature in order to use it appropriately. This chapter discusses what reviewing the literature means in the context of research methodology and how to analyze the scientific literature to get evidence from clinical research for its practical application. The hierarchy of clinical evidence and the method in tracking the best clinical evidence of different types of reviews including systematic reviews and meta-analyses, clinical guidelines, and synopses are also described. This is followed by a brief description of electronic data search and data archiving.
WHAT IS A LITERATURE REVIEW?
A literature review is the methodical process of collection, classification, and evaluation of what other scholars and researchers have written on a particular subject; it should be organized according to the research objectives for which the review has been undertaken.1 Review of literature is most commonly done as a part of introduction to a research report or thesis, but it may also be in the form of a separate document, known as an “annotated bibliography.”
WHY IS LITERATURE REVIEW NECESSARY?
The purpose of a literature review is to determine what knowledge and ideas are already established on a topic and their strengths and weaknesses2 and the knowledge gap (deficit) in that particular area of research. It is not just a summary, but a conceptually organized synthesis of the literature providing a rationale for further research.1 Its main objective is not just to stack up as many articles possible, but to be able to recognize relevant information and to assimilate and evaluate it according to the guiding concept laid down in the research question(s). A literature search should serve two purposes: (i) information seeking: efficiently scan the literature by different search methods to find the useful and relevant literature, and (ii) critical appraisal: identify studies that are unbiased and reliable (valid) (Box 7-1).3