STEP 1: FRAMING THE QUESTION – The research question may initially be stated as a query in free form but reviewers prefer to pose it in a structured and explicit way. The relations between various components of the question and the structure of the research design are shown in Figure 1, This paper focuses only on the question of safety related to the outcomes described below. Structured questions for systematic reviews and relations between question components in a comparative study Box 1 The steps in a systematic review
Step 1: Framing questions for a review The problems to be addressed by the review should be specified in the form of clear, unambiguous and structured questions before beginning the review work. Once the review questions have been set, modifications to the protocol should be allowed only if alternative ways of defining the populations, interventions, outcomes or study designs become apparent Step 2: Identifying relevant work The search for studies should be extensive. Multiple resources (both computerized and printed) should be searched without language restrictions. The study selection criteria should flow directly from the review questions and be specified a priori, Reasons for inclusion and exclusion should be recorded Step 3: Assessing the quality of studies Study quality assessment is relevant to every step of a review. Question formulation (Step 1) and study selection criteria (Step 2) should describe the minimum acceptable level of design. Selected studies should be subjected to a more refined quality assessment by use of general critical appraisal guides and design-based quality checklists (Step 3). These detailed quality assessments will be used for exploring heterogeneity and informing decisions regarding suitability of meta-analysis (Step 4). In addition they help in assessing the strength of inferences and making recommendations for future research (Step 5) Step 4: Summarizing the evidence Data synthesis consists of tabulation of study characteristics, quality and effects as well as use of statistical methods for exploring differences between studies and combining their effects (meta-analysis). Exploration of heterogeneity and its sources should be planned in advance (Step 3). If an overall meta-analysis cannot be done, subgroup meta-analysis may be feasible Step 5: Interpreting the findings The issues highlighted in each of the four steps above should be met. The risk of publication bias and related biases should be explored. Exploration for heterogeneity should help determine whether the overall summary can be trusted, and, if not, the effects observed in high-quality studies should be used for generating inferences. Any recommendations should be graded by reference to the strengths and weaknesses of the evidence
What methodology is used for a systematic review?
Conducting a systematic review: Methodology and steps author(s) Leveraging Evidence for Access and Development (LEAD). from CGIAR GENDER Platform published in 2021 citation Leveraging Evidence for Access and Development.2021. Conducting a systematic review: Methodology and steps. Chennai, India: LEAD at KREA University. Systematic reviews have gained momentum as a key method of evidence synthesis in global development research in recent times. As defined in the Cochrane Handbook on Systematic reviews “Systematic reviews seek to collate evidence that fits pre-specified eligibility criteria in order to answer a specific research question.
- They aim to minimize bias by using explicit, systematic methods documented in advance with a protocol.” It is important to highlight that a systematic review is different from a literature review.
- While a literature review qualitatively summarises evidence with no specific protocol or search criteria, a systematic review is based on a clearly formulated question, identifies relevant studies, appraises their quality and summarizes the evidence by use of a selected explicit methodology.
It is this explicit and systematic approach that distinguishes systematic reviews from traditional reviews and commentaries. It is also important to distinguish between a systematic review and a meta-analysis. While a systematic review refers to the entire process of selection, evaluation and synthesis of evidence; meta-analysis is a specialised sub-set of systematic review.3 Meta-analysis refers to the statistical approach of combining data derived from systematic review.
- It uses statistical techniques to combine the data examined from individual research studies and uses the pooled data to come to new statistical conclusions.
- Hence not all systematic reviews will include a meta-analysis, but a meta- analysis is necessarily in a systematic review.
- The main purpose of this document is to provide guidelines, recommendations and propose a methodology for conducting mixed- method systematic reviews for evidence synthesis for “gender in agriculture and food systems” for the CGIAR GENDER Platform.
In this document we highlight some of the good practices from leading organisations who have contributed to the development of methodology for Systematic Reviews over the years. Throughout the document, we refer to relevant guidelines recommended by these organisations for conducting systematic reviews and adapt it to the proposed questions that include synthesis of qualitative, quantitative and mixed-method evidence.
Can you conduct a systematic review alone?
Systematic reviews cannot be performed alone. One investigator is not sufficient to reduce the risk of bias in the review process. It is essential that Cochrane reviews be undertaken by more than one person. This ensures that tasks such as selection of studies for eligibility and data extraction can be performed by at least two people independently, increasing the likelihood that errors are detected.
Include expertise in the pertinent clinical content areas Include expertise in systematic review methods Include expertise in searching for relevant evidence Include expertise in quantitative methods Include other expertise as appropriate
– National Academies of Sciences, Engineering, and Medicine, Finding What Works in Health Care: Standards for Systematic Reviews, chapter 2, 2011.
What is the layout of systematic review?
Overarching the systematic review is a superstructure or framework. This structure comprises the following components in order: Title-Abstract-Introduction-Methods-Results-Discussion-References.
What are the 4 components of systematic review?
Abstract – This paper examines the subject of systematic reviews from a nursing viewpoint. The history of the evidence-based healthcare movement and the major differences between systematic reviews and traditional literature reviews are discussed. The steps of the process used by those conducting reviews are examined in detail.
What is a meta-analysis vs systematic review?
Formulating research questions – A systematic review attempts to gather all available empirical research by using clearly defined, systematic methods to obtain answers to a specific question. A meta-analysis is the statistical process of analyzing and combining results from several similar studies.
- Here, the definition of the word “similar” is not made clear, but when selecting a topic for the meta-analysis, it is essential to ensure that the different studies present data that can be combined.
- If the studies contain data on the same topic that can be combined, a meta-analysis can even be performed using data from only two studies.
However, study selection via a systematic review is a precondition for performing a meta-analysis, and it is important to clearly define the Population, Intervention, Comparison, Outcomes (PICO) parameters that are central to evidence-based research.
How long should it take to write a systematic review?
Systematic reviews are done with a team of reviewers and they take a while to complete – at least 9 to 12 months depending on the topic. If you don’t have the time for such a large undertaking, consider carrying out a literature review or rapid review.
What is the minimum database for systematic review?
How many databases should be searched for a systematic review? – At least three databases should be used for systematic review literature searches. As explained above, the most common are Embase and MEDLINE, with the third database being chosen based on the subject area of the systematic review.