Critical Appraisal Skills Programme

What Are Systematic Reviews? Why Are They Important?

As a healthcare professional, it is important to stay up to date with the latest research in your field. However, with so many studies and papers available, it can be difficult to assess their quality and reliability.

Systematic reviews are a summary of existing research that helps to answer specific questions and identify gaps in the literature. Through a process of careful data collection, analysis and evaluation, systematic reviews provide a comprehensive overview of the current evidence on a topic.

As we move closer to our Critical Appraisal of Systematic Review Online Training Course, we explore what a systematic review is, why they are important, and how they can help you stay informed about the latest research in healthcare.

What Is A Systematic Review and When Should You Use One?

A systematic review is a rigorous and comprehensive analysis of existing research on a specific topic. It involves identifying, selecting, and appraising multiple studies that meet predetermined inclusion criteria.

The purpose of a systematic review is to summarise the available evidence and provide an unbiased and reliable assessment of the current state of knowledge.

So, when should you use a systematic review? Well, if you want to make evidence-based decisions, a systematic review is a valuable tool. It allows you to gather information from multiple independent studies, which increases the reliability and generalisability of the findings. This is particularly important when there is a large body of research on a topic and you want to make sense of the overall picture.

Commonly you would choose a systematic review over other types of studies, such as primary or empirical studies, because systematic reviews use rigorous methods to minimise bias and ensure the validity of the results. They also employ statistical methods to combine the findings from different studies, providing a more robust and comprehensive understanding of the topic.

Systematic reviews are an essential tool for healthcare professionals who want to stay informed and make evidence-based decisions.

Why Are Systematic Reviews of Research Important?

Systematic reviews of research are incredibly important in the healthcare field for several reasons. Firstly, they provide a reliable and unbiased summary of existing research on a specific topic. Instead of relying on individual studies, systematic reviews gather information from multiple primary studies, ensuring a comprehensive overview of the current evidence.

By summarising research papers, systematic reviews help healthcare professionals make evidence-based decisions. They allow professionals to evaluate the effectiveness of interventions, treatments, or diagnostic methods based on a large body of evidence. This is particularly crucial when it comes to implementing best practices and improving patient outcomes.

Furthermore, systematic reviews help identify gaps in the literature, highlighting areas that require further research. This can guide researchers and clinicians in developing new studies to address unanswered questions and contribute to the advancement of knowledge in the field.

As a healthcare professional, incorporating systematic reviews into your practice will enhance your ability to stay informed, make informed decisions, and provide the highest quality of care to your patients.

Systematic Review vs Meta-Analysis

Systematic reviews and meta-analyses are often mentioned together, but they are not the same thing.

  • A systematic review is a comprehensive analysis of existing research on a specific topic.
  • A meta-analysis is a statistical technique used to combine the results of multiple studies.

So, how do you know if a meta-analysis is required? Well, if you want to quantitatively summarise the findings from different studies and assess the overall effect size, a meta-analysis is the appropriate choice. On the other hand, if you want to provide a comprehensive overview of the evidence without quantitative synthesis, a systematic review alone may suffice.

Other Types Of Systematic Review?

In addition to traditional systematic reviews, there are other types of systematic reviews that can provide valuable insights and summarise research in different ways. These include scoping reviews, rapid reviews, and umbrella reviews.

  • Scoping reviews aim to map the available evidence on a broad topic, identifying key concepts, sources, and types of evidence.
  • Rapid reviews, as the name suggests, aim to provide a timely review of evidence within a shorter timeframe. These reviews are often used when quick decision-making is required or when there is limited time for a comprehensive systematic review.
  • Umbrella reviews, on the other hand, summarise systematic reviews and meta-analyses on a specific topic. They provide a higher-level overview and synthesis of existing reviews, giving a broader perspective on the current state of knowledge.

These different types of systematic reviews offer flexibility and varying levels of depth in summarising research, allowing healthcare professionals to choose the most appropriate approach based on their specific needs and time constraints.

What Data Should Have Been Extracted For A Systematic Review

When it comes to conducting a systematic review, the type and amount of data that should be included are crucial to the validity and comprehensiveness of the study. Ideally, a systematic review should be inclusive of all relevant studies and data sources that address the research question. This means that any empirical studies, literature reviews, or unpublished data should have been included in the review. Additionally, it is important that the search strategy used to collect data, including keywords, databases, and inclusion and exclusion criteria, has been documented.

When reviewing the data, researchers should have considered factors such as the quality and relevance of the studies, as well as any potential bias that may exist. Ultimately, the data included in a systematic review should provide a comprehensive overview of the existing research on a topic, helping to inform future research and practice.

How To Critically Appraise A Systematic Review

When critically appraising a systematic review, it is important to approach the process with a systematic and methodical mindset. Here are the steps you can take to ensure a thorough and accurate assessment:

  1. Start by familiarising yourself with the research question being addressed by the systematic review.
  2. Assess the methodology used to conduct the review, including how the studies were identified, the inclusion and exclusion criteria used, and the data extraction methods employed.
  3. Evaluate the quality of the studies included in the review, considering factors such as the study design, the representativeness of the study population, and the risk of bias.
  4. Analyse the statistical methods used to synthesise the data across studies, and evaluate the appropriateness of the conclusions drawn.
  5. Check whether the results of the review are consistent with the available evidence on the topic.
  6. Consider the implications of the findings for clinical practice, policy, or future research.

Throughout the critical appraisal process, you may find it helpful to utilise frameworks such as PICO, PICo, SPICE, or SPIDER to guide your assessment. These frameworks provide a structured approach to evaluating the research question, study design, and other key aspects of the systematic review.

By following these steps and using appropriate frameworks, you can critically appraise a systematic review with confidence and ensure that you are using the most reliable and relevant evidence to inform your healthcare practice.

How Many Studies Should Be Included in a Systematic Review?

Determining the appropriate number of studies to include in a systematic review can vary depending on the research question and the available evidence. Generally, a systematic review should aim to include all relevant studies that meet the predetermined inclusion criteria.

The goal is to provide a comprehensive overview of the current evidence on a topic. However, it is important to strike a balance between inclusiveness and feasibility. Including too few studies may limit the validity and generalisability of the findings, while including too many studies may result in an overwhelming amount of data to analyse.

Ultimately, the number of studies included in a systematic review should be determined based on the specific research question, the quality and relevance of the available studies, and practical considerations such as time and resources.

How Long Does a Systematic Review Take to Perform?

Performing a systematic review can be a time-consuming process that requires careful attention to detail and adherence to rigorous methodology. The length of time it takes to complete a systematic review can vary depending on various factors, such as the complexity of the research question, the number of studies included, and the availability of resources.

On average, it can take several months to a year to complete a systematic review. However, it is important to prioritise quality over speed to ensure the reliability and validity of the findings. The time investment in conducting a systematic review is worthwhile, as it provides healthcare professionals with a robust and comprehensive understanding of the current evidence on a topic.

AI & Systematic Reviews

Artificial Intelligence (AI) technology has revolutionised how systematic reviews are conducted in recent years. By automating certain processes and streamlining data extraction, AI has made it possible to complete reviews in a fraction of the time and with more precision than ever before. Specifically, machine learning algorithms can now be utilised to analyse massive datasets quickly and identify patterns that were previously overlooked, leading to more nuanced and accurate conclusions. This allows for more reliable results and faster turnaround times. Furthermore, AI can also help eliminate human bias, resulting in more impartial conclusions.

Which Reporting Standard Should Systematic Reviewers Use?

When it comes to reporting the findings of a systematic review, there are several reporting standards that can be used to present research in a clear and transparent manner.

One commonly used reporting standard is the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). PRISMA provides a checklist of items that should be included in a systematic review report, ensuring that all relevant information is documented and accessible to readers.

Another widely recognised reporting standard is the Cochrane Handbook for Systematic Reviews of Interventions, which provides detailed guidance on conducting and reporting systematic reviews in the field of healthcare. By following these reporting standards, reviewers can facilitate the replication of the study by other researchers.

Where to Find Systematic Reviews

If you're looking for systematic reviews, there are several places to look. The Cochrane Library is a well-known database that specialises in systematic reviews and evidence-based healthcare. They offer a wide range of systematic reviews on various topics, ensuring you have access to the most current and reliable evidence.

Other places to look include databases such as:

These can help you stay informed and make evidence-based decisions in your healthcare practice.

What is Publication Bias?

Publication bias refers to the tendency for studies with positive or significant results to be more likely to be published and accessible than studies with negative or nonsignificant results. This can lead to an incomplete and biased representation of the true body of evidence on a topic.

Publication bias can occur due to various factors, such as journal preferences for publishing certain types of studies, researchers' tendencies to prioritise and submit positive results, or selective reporting of outcomes within a study. Being aware of publication bias is crucial for healthcare professionals, as it can impact the validity and reliability of the evidence they rely on for decision-making.

Download our Free CASP Systematic Review Checklist

All our critical appraisal checklists are completely free for researchers to use. Download our free checklist from the CASP tools checklist page.

Alternatively, download our systematic review critical appraisal PDF.

If you need further help critically appraising your systematic review join a virtual workshop:

*COMING SOON* Critical Appraisal of Systematic Reviews – Online Training Course

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