Systematic Literature Review (SLR) – Tips & Tricks
Authors: Kapil Khambholja Ph.D. & MW- RWE team, Genpro research
What is SLR?
In simple terms a Systematic Literature Review (SLR) is a study of studies. It attempts to collect comprehensive existing evidence on a specific topic to answer a specific research question in a structured manner.
What is SLR used for?
Systematic Literature Review can be used for answering varied research questions with the help of evidence gathered and analysed from the published literature. At the same time, it can also help to identify the gaps in existing literature which otherwise will get unnoticed. Various uses of SLR can be categorized as per the research questions or aim of SLR (1):
- To evaluate the effectiveness of a certain treatment/practice in terms of its impact on outcomes
- To investigate the experience or meaningfulness of a phenomenon
- To determine the costs associated with an approach or treatment strategy, particularly in terms of cost-effectiveness or benefit
- To determine the prevalence and/or incidence of a certain condition
- To determine how well diagnostic tests works in terms of its sensitivity and specificity for a diagnosis
- To answer qualitative research questions
- To determine the association between particular exposures/risk factors and outcomes
- To review and synthesize current expert opinion, text, or policy on a certain phenomenon
- To evaluate the psychometric properties of a certain test, normally to determine how the reliability and validity of a test or assessment
- To determine the overall prognosis for a condition, the link between specific prognostic factors and an outcome and/or prognostic/prediction models and prognostic tests.
- To examine and investigate current research methods and potentially their impact on research quality.
What is the importance of a good quality SLR?
A good quality SLR can give a comprehensive overview of a problem or research question or state of art. It brings out the gaps in existing research and suggests what has not worked so far for solving a problem. If used appropriately, a SLR can help analyse past research and guide future direction of the research in a given field. High quality SLR becomes basis for suggesting further research studies of both observational and interventional types. It also helps in synthesizing qualitative or quantitative evidence and formulate certain hypotheses. A good quality SLR, in the nutshell, answers the very question it aimed for, in the best possible manner.
Challenges while performing SLR: Information overload is often encountered while performing SLR when we need to rethink about our search strategy, to make it more efficient for answering the research question in a systematic manner.
- Comprehensive review needs to read many articles and time taken often conflicts with short timelines of the projects. Many times, cross-references increase the number of articles to be reviewed without much of new information.
- Certain articles are not available as free text, and they become very important for answering the question.
- Newer research articles keep pouring in a situation like COVID-19 pandemic, and while the SLR is undertaken & the publication is processed, a lot of new information might become available.
Easy access to information can cross-fertilize many researchers, and by the time we submit the article, someone else might already publish on the same topic. Nevertheless, the uniqueness of research question makes an SLR worth publishing to provide a different perspective on the same topic. Researchers might adapt their existing SLR to throw light on a different viewpoint.
Ten Tips for conducting a better SLR:
Here are few simple tips for undertaking a better SLR:
- Formulate your research question and research strategy thoroughly
- Register your protocol prospectively for conducting a systematic literature review.
- Be comprehensive in your search study to reduce publication bias. Include as many sources of information as possible.
- Keep keywords as broad as possible to include just relevant articles and avoid unnecessary retrievals.
- At least two reviewers should conduct review independently.
- Screen titles, then abstracts, and then full text to progressively reduce the workload of reading extensive articles.
- Use PRISMA Flow Diagram to depict inclusion and exclusion of studies (2).
- Pilot data extraction sheet on few studies followed by comprehensive & structured data extraction.
- Risk of bias in studies should be investigated to maintain the quality of synthesis by looking as certain parameters like sample size and prospective nature.
- Use Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and its relevant extensions for reporting SLR findings (3).
Future of SLR:
While researchers and companies have relied heavily on SLR and meta-analysis for years, the regulatory bodies are increasingly opening up avenues of use of RWE and literature-based evidence to support several decisions and even the extension of approvals. Besides the best practices used by experienced researchers for undertaking SLR, one should look to adopt technological interventions to improve the quality and speed of research using SLR. With the use of advanced tools based on Artificial-intelligence, machine learning (AI-ML) and Natural Language Processing (NLP) the researchers can focus on the core intellectual thought process while designing the SLR hypothesis and reduce the manual efforts. With the use of technology, human intelligence can be put to use in the right direction. Days are not far where the AI will be able to synthesize SLR questions on their own and provide the outcome to researchers in a fraction of time compared to conventional ways…
Munn Z, Stern C, Aromataris E, Lockwood C, Jordan Z. What kind of systematic review should i conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences. Vol. 18, BMC Medical Research Methodology. BioMed Central Ltd.; 2018.
- PRISMA FLow Diagram [Internet]. [cited 2020 May 14]. Available from: http://prisma-statement.org/PRISMAStatement/FlowDiagram
Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JPA, et al. The PRISMA Statement for Reporting Systematic Reviews and Meta-Analyses of Studies That Evaluate Health Care Interventions: Explanation and Elaboration. PLoS Med. 2009 Jul 21;6(7):e1000100.
Tags: Systematic Literature Review, SLR, Medical Writing, Scientific Writing, RWE, AI-ML, NLP, FutureofSLR