According to Cochrane, a systematic review is defined as an attempt “to identify, appraise and synthesize all the empirical evidence that meets pre-specified eligibility criteria to answer a given research question. Researchers conducting systematic reviews use explicit methods aimed at minimizing bias, in order to produce more reliable findings that can be used to inform decision making.”

When to Use It: Per Grant & Booth (2009) and Lasserson et al. (2019), a systematic review might be right for you if you're interested in:

• Answering a specific question(s) that is related to an intervention, diagnostic test, prognostic factor, other health or healthcare topic

• Summarizing the most reliable information on a specific topic, and do so using rigorous, unbiased methods

• Summarizing a variety of study designs such as mixed methods, qualitative, and quantitative studies for a specific topic

The following characteristics, strengths, and challenges of systematic reviews are derived from Booth (2016) and Grant & Booth (2009). 

Characteristics:

• One of the most prominent types of reviews

• The goal of a systematic review is to systematically search for, appraise and synthesis research evidence

• A key feature involves the reporting of clear, transparent, and reproducible methods used to achieve the systematic review

• The end goal is to produce a synthesized review that limits bias

Strengths:

• The point of a systematic review is to gather all relevant knowledge on a specific topic 

• Can involve a mix of study designs including quantitative, qualitative, and mixed methods

Challenges:

• Limiting inclusion criteria for single study design restricts the insights one can gain from information

• Time-consuming

• Requires a team

The following resources are considered to be the best in the field of systematic reviews in terms of guidance and reporting.

METHODS & GUIDANCE

• Systematic Reviews: CRD's guidance for undertaking reviews in health

The Centre for Reviews and Dissemination's (CRD) guidance is intended to aid health researchers in understanding proper conduct and best practices when conducting a systematic review.

• Cochrane Handbook for Systematic Reviews of Interventions 

Defined as "the official guide that describes in detail the process of preparing and maintaining Cochrane systematic reviews on the effects of healthcare interventions". It includes: "guidance on the standard methods applicable to every review (planning a review, searching and selecting studies, data collection, risk of bias assessment, statistical analysis, GRADE and interpreting results), as well as more specialised topics (non-randomized studies, adverse effects, complex interventions, equity, economics, patient-reported outcomes, individual patient data, prospective meta-analysis, and qualitative research)" (Cochrane, About the Handbook, para. 2).

• Joanna Briggs Institute (JBI) Reviewer's Manual 

A comprehensive guide focusing primarily on the conduct of systematic reviews, covering a broad range of questions and study designs. 

REPORTING GUIDELINE

• PRISMA 2020

PRISMA (2020) is a 27-item checklist that replaces the PRISMA (2009) statement, which ensures proper and transparent reporting for each element in a systematic review and meta-analysis. "It is an expanded checklist that details reporting recommendations for each item, the PRISMA 2020 abstract checklist, and the revised flow diagrams for original and updated reviews."

SUPPLEMENTARY RESOURCES

Check out the supplementary resources page for additional information on systematic reviews, including online courses and books.