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
Is 4 papers enough for systematic review?
Generally, you’d want to appraise and synthesize two to three studies for a sound systematic review, especially if the topic has an adequate amount of existing literature. However, there is no set minimum number of studies to include in a systematic review.
Can one person do systematic review?
The methodology for systematic reviews is designed to be rigorous and isn’t suitable for individual researchers and those working to a tight timescale. To learn more about different review methodologies and understand which type of review will best to undertake for your topic, we recommend you read ths following article: Grant, M.J.
| Is there sufficent literature on your topic to warrant a review? As systematic reviews synthesise existing evidence and provide synthesis of published studies, it is a requirement that there is sufficent literature available on a topic for a review to be successful. You can carry out a scoping search (background search to assess the amount of literature available) before deciding on the best type of review to address your research question. If you find there isn’t much literature available on your topic then you may decide to conduct a ‘systematic search and review’ which aims to combine the strengths of the more traditional critical review with a systematic search process. |
| Do you have the time to complete a systematic review? Systematic reviews of medical interventions are carried out over a long period of time ( mean: 67.3 weeks ) and good quality, rigorous systematic reviews require multiple authors and experts to support the different stages of the review process. Reviewers should search multiple bibliographic databases (at least three relevant databases) to ensure that they have been comprehensive in their approach, and utilise other searching methods such as hand-searching to ensure all trials, or relevant studies are identified. Hand-searching is a manual process whereby an author identifies relevant studies for the review by examining citation lists in journal issues or in grey literature, The search process can be time consuming, so if you are on a tight deadline a different type of review methodology is likely to more appropriate. |
| Do you have methods to reduce the risk of bias in place? Systematic reviews follow a study protocol which details the methods that will be used in the review. Protocols are essential to ensuring a rigorous approach and can help verify that previous systematic reviews have not already answered the research question. |
| Do you have support available to work on the review? Systematic reviews should not be carried out by one person as this may lead to increased bias in searching, screening and data selection. A second person should be available for screening and article selection and this will reduce the chance of any errors made. Well conducted systematic reviews are carried out by teams with expertise in the topic under review, with the support of information professionals (librarians or information specialists) advising on the search strategy, database selection and reporting methods. If you are a current student, our team of librarians can advise you on good practice for search strategy formation and provide advice on searching databases efficiently. They will not be able to check your search strategy, or help you generate keywords as your search strategy will be assessed as part of your academic work. |
There are many other types of review that you can undertake and often these are defined by the amount of time you have and the amount of literature that is available. Scoping reviews are often used to clarify gaps in knowledge or assess the literature available on a given topic.
Sometimes, they can be used to determine if a systematic review is necessary. This article provides information to help you understand the differences between these review types: Munn, Z., Peters, M.D.J., Stern, C. et al. Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach.
BMC Med Res Methodol 18, 143 (2018). https://doi.org/10.1186/s12874-018-0611-x You may find our guide on scoping reviews helpful.
Can anyone write a systematic review?
A systematic review cannot be conducted by one person. You need a team that includes: Subject experts with clinical and methodological expertise. Two people to review the results independently.
What makes a systematic review weak?
These may include risks of bias, such as selection bias, inadequate blinding, attrition bias, and selective outcome reporting; inconsistency that includes clinical or statistical heterogeneity; and imprecision that can lead to Type I and Type II errors. Another important consideration is publication bias.
When should you not do a systematic review?
Over the past few years, there has been an explosion in the number of systematic reviews conducted and published — although a systematic review is an inappropriate or unnecessary research methodology for answering many research questions. Systematic reviews can be inappropriate for a variety of reasons:
The topic is too new and there aren’t enough relevant published papers to synthesise and analyse for a systematic review Many other people have already published systematic reviews on the topic (do a scoping search on the Cochrane Library, or by limiting your search results to systematic reviews on other databases, to see if other systematic reviews exist) You do not have enough time to conduct a systematic review (most systematic reviews will take between six to eighteen months on average to complete) You do not have any coauthors with whom to conduct the systematic review (systematic review methodology requires two authors to independently screen references to determine which fit pre-defined inclusion criteria)
If you feel your circumstances or research topic match any of the above, a systematic review may not be the best approach for you. You could still do a literature review, and adopt elements of systematic review methodology, rather than a systematic review.
How many references should a systematic review have?
LITERATURE SEARCH – A systematic review is only as good as the data on which it is based, that is, the primary studies. To ensure that the widest scope of primary research is identified, a thorough and complete search of the literature is needed. The best way to accomplish this is to have help from a librarian with expertise in the area of systematic reviews in defining the search terms, search strategies, and databases to be used.
- The rule of thumb for a systematic review literature search is that more than 2 databases should be used.
- For the casual reader, the databases that should be used for a particular systematic review can be difficult to judge, but generally databases beyond just MEDLINE should be searched.
- Ideally, articles in languages other than English should be included, and there should be an attempt to find unpublished research and research that has not been formally published in a journal.
This “grey literature” is the most difficult to find. Grey literature has been defined as “that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers”.5 It can include reports, theses, conference proceedings, technical specifications and standards, noncommercial translations, bibliographies, technical and commercial documentation, and official documents not published commercially (such as government reports).5 The instantaneous nature of the Internet has led to a proliferation of this type of literature, but the challenge lies in finding it.
- Searching the websites of agencies and organizations that may be involved in the area of interest is a reasonable way to start.
- Grey literature repositories and gateways have evolved and offer another method for researchers to find primary evidence not available in the peer-reviewed literature.5 Again, searching for grey literature can be much easier with the help of a librarian.
In addition to a formal bibliographic search and a grey literature search, hand-searching of reference lists or key journals should be performed, as well as searching of controlled trial registers. This type of search can also be guided by a librarian.
The difficulty with the search stage of a systematic review is keeping all of your potential studies organized. Online or shareable citation software is an easy way to manage the potentially large number of studies being considered. By using an online version, you can allow your co-researchers to have access to the studies.
Given that at least 2 researchers will be needed to review the potentially included studies, online citation management allows for easy access by the multiple researchers.
Is meta-analysis a systematic review?
A meta-analysis differs from a systematic review in that it uses statistical methods on estimates from two or more different studies to form a pooled estimate.
What is a 12 step approach?
12-step programs are powerful peer support groups that help people recover from substance use disorders, behavioral addictions, and sometimes other co-occurring mental health conditions.12-step programs also help people achieve and maintain abstinence from substances.
What are the parts of a 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.
How many steps are there in a systematic approach?
This learning module introduces a systematic approach to solving problems by using a six-step process. This approach is used throughout industry to solve simple to complex problems. Activities provide the opportunities to this six-step process in a real life situation as well as MEMS process problem.