How to Write Systematic Review | Acadiz

A systematic review is more than just a collection of studies—it’s a rigorous and transparent process that synthesizes evidence to answer a specific research question. By following a repeatable and structured method, a systematic review provides a comprehensive and unbiased summary of all relevant information, offering invaluable insights for researchers, practitioners, and policymakers alike.

A systematic review is a structured, repeatable process that systematically identifies, selects, and synthesizes all available sources of information related to a specific research question. The goal is to minimize bias by applying transparent, predefined methods to ensure comprehensive and reliable results. Though the writing process follows a general review format, it is distinguished by its rigorous steps to ensure evidence is rigorously evaluated and synthesized. These six steps include defining eligibility criteria, conducting a thorough search for studies, appraising their quality, and integrating findings to address the research question.

Step 1- Formulate the Research Question

Formulating the research question is arguably the most crucial step in conducting a systematic review. A clear research question will:

• Enhance your ability to effectively communicate your research to other researchers and practitioners.
• Guide your decisions as you plan and execute your systematic review.

A well-structured research question for a systematic review typically includes four components, which can be remembered using the acronym PICO:

1. Population(s) or problem(s)
2. Intervention(s)
3. Comparison(s)
4. Outcome(s)

You can rearrange these components to construct your research question in the following format:

What is the effectiveness of I versus C for O in P?

In some cases, you may wish to incorporate a fifth component: the type of study design. When including this component, the acronym changes to PICOT:

1. Type of Study Design(s)

The fifth component, Type of Study Design(s), is added when you want to specify the kinds of studies to include in your systematic review (e.g., randomized controlled trials, cohort studies, or qualitative studies). This addition helps ensure the research question is targeted at a specific evidence base, improving the relevance and reliability of the review. For more detailed insights on topic selection, you can visit our website, the Acadiz.

Step 2- Defining Eligibility Criteria

Explain Inclusion and Exclusion Criteria: Use these criteria to decide which studies to include or exclude in your search. 

Eligibility criteria for systematic reviews and meta-analyses should align with the research question and be structured using the PICOS framework (Population, Intervention, Comparator, Outcomes, Study Design). Key considerations include defining the population, interventions, outcomes, study designs, and publication characteristics while ensuring clarity and feasibility. Consulting stakeholders and piloting the criteria help refine the process and ensure robust results.

Step 3- Study Selection

Searching all the relevant studies that meet the eligibility criteria is often the most time-consuming part of a systematic review. Conducting a thorough search for these studies is crucial to minimize bias. Additionally, Study selection should be a collaborative effort involving three individuals: two people should independently conduct the extraction, while the third person will be responsible for resolving any disagreements that arise.

Your search strategy will depend on your specific field and research question, but generally, sources can be categorized into four main types:

1. Databases: Utilize multiple databases of peer-reviewed literature, such as PubMed or Scopus. Carefully consider how to phrase your search terms and include synonyms for each keyword. Incorporating Boolean operators can also enhance your search.
2. Handsearching: In addition to using databases, manual searches are necessary. One effective approach is to browse through relevant journals or conference proceedings. Another useful method is to examine the reference lists of studies that are already relevant to your research.
3. Gray Literature: This refers to documents produced by governments, universities, and other organizations that are not published by traditional publishers. Graduate student theses are an important type of gray literature, which can be accessed through the Networked Digital Library of Theses and Dissertations (NDLTD). In the medical field, clinical trial registries serve as another key source of gray literature.
4. Experts: Reach out to experts in your field to inquire about any unpublished studies that should be included in your review.

Databases are the most reliable source for systematic reviews due to their rigorously peer-reviewed content. However, to ensure comprehensiveness, a combination of all four methods—databases, handsearching, gray literature, and expert consultations—is ideal. This approach mitigates the limitations of individual methods, ensuring a thorough and unbiased review.

At this stage, you do not need to read the articles in detail. Instead, focus on saving any potentially relevant citations using bibliographic software, such as Scribbr’s APA, Mendeley, or Zotero.

Step 4- Data Extraction

Extracting data involves systematically collecting information from the chosen studies in a Microsoft excel sheet. There are two main types of information you need to gather from each study:

1. Study Information: This includes details about the study’s methods and results, which may vary based on your research question. Important elements to consider are the year of the study, study design, sample size, context, research findings, and conclusions. If any data is missing, it will be necessary to reach out to the study’s authors for clarification.
2. Quality Assessment: This entails evaluating the quality of the evidence, including any risks of bias present in the studies. To collect this information, standardized forms are recommended. Sample forms can be found in resources such as The Registry of Methods and Tools for Evidence-Informed Decision Making.

Step 5- Synthesize the Data

Synthesizing the data involves combining the information you have gathered into a coherent narrative. There are two main approaches to synthesizing the data:

1. Narrative (Qualitative): This approach summarizes the information in a written format. You should discuss the studies you reviewed and evaluate their overall quality.
2. Quantitative: This method employs statistical techniques to summarize and compare data from different studies. The most common quantitative approach is a meta-analysis, which enables you to combine results from multiple studies into a single summary result.

Step 6- Write and Publish a Report

The purpose of writing a systematic review article is to share the findings of your research question and to explain the process you used to arrive at those findings. Your article should include the following sections:

1. Abstract: A brief summary of the review.
2. Introduction: This section should present the rationale for the review and its objectives.
3. Methods: Describe the selection criteria, search methods, data extraction methods, synthesis methods and quality appraisal methods used in your review.
4. Results: Present the outcomes of the search and selection process, provide study characteristics, assess the risk of bias in the studies, and summarize the synthesis results.
5. Discussion: Interpret the results and discuss the limitations of your review.
6. Conclusion: Provide the answer to your research question and discuss its implications for practice, policy, or further research.

To ensure that your report meets all requirements, you can use the PRISMA checklist. Once your report is complete, you can publish it in a systematic review database, such as the Cochrane Database of Systematic Reviews, or submit it to a peer-reviewed journal. For more information, please connect us at Linkedin.