Systematic review article and meta-analyses constitute a group of Level 1 and 2 studies and are considered at the highest level of evidence-based medicine (EBM) 1. Whereas unsystematic, narrative review articles are marred by author bias, as it is more probable to embrace only research chosen by the authors, thereby introducing bias. We believe that since systematic review articles are becoming more easily understood and accepted in medical literature, they will eventually be the format accepted for the reviews and possible publication in indexed journals. This blog will allow our readers to comfortably comprehend these reviews and feel at ease in formatting their own systematic review article in the future.
The ability to carry out an enlightening systematic review of the available literature, and its inherent limitations, quality and potential are an essential skill for any researcher to develop. Not only does it help answer the hypothetical question, it also enables valuable information and provides guidance about the planning and recommendation of the value of any innovative research.
The process of writing systematic review articles takes place in order to put multiple studies or researches into an organized form so that useful information can be extracted from. Writing a good systematic review directly determines the entire basis of how good a meta-analysis of any research program is. Therefore, more competently the conducted systematic reviews are, more useful conclusions can be drawn from the relative studies. A systematic literature review is a crucial step of evidence-based medicine (EBM). It does not only aim to organize studies and make a useful interpretation based on them but also helps in an appropriate assessment of the quality of different studies. Thus making your research process very high yield and enables targeted questions to be answered through it.
A systematic literature review can be defined as an endeavor to “identify, appraise and synthesize all the empirical evidence that meets pre-specified eligibility criteria to answer a given research question” (Cochrane definition, 20132).
The aims of a systematic review can be varied and include:
- Elucidating the relative strengths and drawbacks of the available literature on the question,
- Summarizing an enormous expanse of literature,
- Resolving literature disagreements,
- Appraising the necessity for a large clinical trial,
- Circumventing the need for an unwarranted trial,
- Increasing the statistical power of smaller studies,
- Improving the precision or identify a smaller treatment effect, and
- Improving the generalizability of treatment outcomes.
Types of systematic reviews:
The types of systematic reviews for any literature can be defined more as steps of drawing a conclusion on evidence collected from the literature. At every step, the information becomes more refined and properly defined. The three types of systematic reviews are:
- Qualitative reviews: This type of systematic review is based on summarizing the studies that have been conducted on a subject.
- Quantitative reviews: Quantitative reviews make use of combining the statistical data or conclusions of different studies together. The aim is to organize two or more than two multiple studies for drawing useful conclusions.
- Meta-analysis: Meta-analysis is the process of bringing together the data collected on the basis of systematic reviews. This is more of a proceeding step that follows systematic reviews.
Steps for Conducting a Systematic Review:
A sound systematic review needs a few protocols to be followed. Following these protocols and carefully taking all the essential steps assures that the systematic review conducted is high-yield. Systematic reviews are listed as one of the top forms of evidence-based medicine (EBM). The essence of a good EBM lies in its forming elements like meta-analysis and systematic reviews being efficient and decisive.
We have briefed the pivotal steps that are to be respected while conducting a systematic review.
1) Formulation of a Research Question
2) Study Selection Criteria
3) Developing a Research Protocol
4) Data Extraction
5) Data Analysis
6) Interpretation of Results
1) Formulation of a Research Question:
A hypothesis could be defined as a projected rationalization for an observation. It could either be investigated ( the scientific hypothesis) or it might be carried forward (working hypothesis).
- You need a primary research question in order conduct a sound systematic review. Your systematic review has to revolve around this question. An efficient research question typically comprises of;
- Patient groups studied;
- Tests, or exposure for the population;
- Alternative intervention or Control; and
- Results of the interventions.
This first step is crucial because it gives your project a clear-cut direction, which can be followed to reach the targeted goal. A number of useful questions can be addressed which elaborate any condition in a better way. For instance, the etiology of the disease, the results of different diagnostic tools, the occurrence of disease, and certain other relevant things can be addressed in this. Developing a primary research question thus gives a firm basis to the conduction of your systematic review article.
Please keep in mind that a vague hypothesis/question would most likely to lead you to a vague conclusion/answer.
Good systematic review questions could address either of the following:
- Phenomena associated with disease or interventions
- Disease or its related condition frequency
- Diagnostic precision
- Disease etiology and/or its risk factors
- Prognosis, and
- Efficacy of the intervention studied
2) Study Selection Criteria:
It is important to identify the relevant studies that can be specifically helpful for your research. Some criteria have to be set which determines the inclusion or exclusion of a certain study in your program. You are advised to carry out extensive research on different levels of studies that are available regardless of the language limitations. A few researchers may find it exhausting and strenuous to collect data from different languages but integrating the studies from different languages can largely extend the scope of your study.
After the extensive mass of literature has been collected, it is necessary to filter them on the basis of your study selection criteria. Your criteria should aim to select those studies that can be highly efficient for your subject and exclude those studies, which are less relevant.
3) Developing a Research Protocol:
Developing a research protocol is important because it helps to develop an outline of your research goals. It is a precise yet comprehensive explanation of your literature goals and is thus important in organizing the data and information. Nowadays journals require you to submit the protocol along with your manuscript. Authors of systematic reviews are expected to make use of the either EQUATOR (http://www.equator-network.org/) or PRISMA statement or similar other guidelines to format their protocol. The PRISMA Statement consists of a checklist (27-items) and is accompanied by a flow diagram. It is a guide for authors about how to develop a protocol for the review and what needs to be included while writing the systematic review.
4) Data Extraction:
Data extraction is important because helps in reaching to the useful conclusions. The common method of data extraction is using an electronic or paper standardized form. This is by far the most efficient method of data extraction and is used worldwide by a large number of people. A standardized data extraction form comprises of certain essentials like the reference of the study. It also explains the objective of the study and the type of population chosen for the study process. Other factors like the demographic analysis; intervention control, and outcomes are also discussed in the standardized data extraction forms.
5) Data Analysis:
The step of data analysis further polishes the information that you are collecting for your systematic review. Other useful techniques for serving the purpose may consist of quality appraisal and study quality assessment. The most efficient method for data analysis is to present your study evaluation in a tabulated form. Tabulation of the study helps in clearly understanding the results obtained from the data. All the interventions, the control and study groups, the outcomes and other important information should be presented in the data analysis.
6) Interpretation of Results:
The correct interpretation of results determines the quality of your systematic review and it needs to be carried out with caution. Poor interpretation of results always signals to the low quality of the study and can be characterized by poorly defined conclusions.
Once you have collected sufficient quantitative data, it is advised to put it through an extensive meta-analysis, using statistical methods. If you are not confident, please do consult a statistician before the review begins. As a starter, a simple tip is provided. If you are conducting a study to assess the collective efficacy of a drug across all studies in the literature, an effective method of merging different measures of outcomes is to use odds ratios calculated from each outcome with 95% confidence intervals. Follow this with analysis of statistical significance to estimate the degree of effect and heterogeneity between all the studies. Ranked by effect size, the data could then be plotted into a ‘forest-plot’.
Common limitations with systematic reviews could include:
- Important studies are neglected due to an inadequate literature search.
- Too many biases present.
- Vague hypothesis or research question.
- Ambiguous review methodology.
- The findings of the review lead to inconclusive inference.
A systematic review article benefits healthcare professionals to stay conversant with the precipitously changing medical literature. Hence, a good systematic review article should be able to defend that it conducted an all-encompassing systematic search, identified, selected, evaluated, and amalgamated research evidence pertinent to the hypothesis/question, using a methodology that was unambiguous, reproducible, and thereby incorporated the least bias.
By being mindful of our easy-to-follow step-by-step guide for writing a systematic review, you are sure to conduct the process in an efficient manner. This holds true for those who already have experience in this regard as well as for those who do not have a formal training of the process. Any researcher who wants to succeed in presenting their research as a competitive distribution needs to carry out the statistical analysis in a proficient way. Once you realize the importance of carrying out our research in a systemized way, you can conduct a quality systematic review by following our aforementioned points.
- Wright RW et al. Integrating Evidence-based Medicine into Clinical Practice. J Bone Joint Surg Am. 2007;89: 199–205.
- The Cochrane Library; http://www.thecochranelibrary.com/view/0/index.html
- EQUATOR Network. Available at: www.equator-network.org.
- The Cochrane Collaboration. The reliable source of evidence in healthcare. Available at: www.cochrane.org.
- CEBM Centre for Evidence-based Medicine. Available at: www.cbem.net
- The Campbell Collaboration. Available at: www.campbellcollaboration.org.
Anurag Tewari MD & A. P Singh MD (APtizer)
Image Courtesy: ImageBase
How to Cite this Article: Tewari A, Singh AP (June 2016). Retrieved on (Month/Date/Year) from How to a Systematic Review Article.
Also, read the following Articles that will help you write, organize and write an error-free manuscript that has high chances of getting accepted by the journal.
- TIPS ON WRITING A GOOD RESEARCH PAPER TITLE
- TIPS: HOW TO WRITE AN ABSTRACT FOR YOUR RESEARCH ARTICLE?
- TIPS TO WRITE THE INTRODUCTION FOR YOUR RESEARCH ARTICLE
- HOW TO WRITE THE METHODS SECTION OF A RESEARCH ARTICLE?
- HOW TO DRAFT THE RESULTS SECTION OF YOUR RESEARCH ARTICLE
- HOW TO WRITE THE DISCUSSION OF A RESEARCH ARTICLE?
- HOW TO WRITE REFERENCES IN YOUR RESEARCH ARTICLE
- HOW TO WRITE AN EFFECTIVE CASE REPORT FOR A JOURNAL?
- WHY PUBLISH YOUR SCIENTIFIC WORK IN A PEER-REVIEWED JOURNAL?
- WHY IS YOUR RESEARCH PAPER REJECTED BY THE JOURNAL?