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Kornhauser Health Sciences Library

Systematic Reviews and Evidence Syntheses

Choosing the right review type

While systematic reviews and meta-analyses are the most well-known, there are a wide variety of other evidence synthesis types that all serve different purposes and may be more suitable for certain research questions or contexts. 

Each type of evidence-synthesis has its strengths and limitations, and the choice of the most appropriate approach depends on:

  • Choice of research question
  • Available resources
  • Time constraints
  • Volume and quality of evidence available to be reviewed
  • Specific objectives of the project

In addition to the information below, the following tools are available to help you decide on your review methods:

Review types

  • Focused: concerned with a specific, narrowly defined research question
  • Comprehensive: aim to synthesize all available evidence on the research question
  • Rigorous: follow a predefined protocol and use systematic methods to search for, select, appraise, and synthesize relevant studies
  • Structured: conform to reporting guidelines, ensuring transparency and replicability
  • A statistical technique used to combine the results of multiple independent studies
  • A means to obtain a quantitative summary (effect size) of the intervention or outcome of interest

Do not attempt a meta-analysis without:

  • First conducting a systematic review: to be meaningful and not misleading, meta-analysis must draw from a methodically collected set of primary sources.
    • See the Cochrane Handbook, section 10.1
  • A qualified statistician: meta-analysis is a complex statistical technique, easily fumbled, and highly misleading when mishandled. It should not be attempted by non-experts.
    • Meta-analysis is not appropriate for all systematic reviews. Consultation with a statistician is necessary to determine whether it should be attempted.
  • Expedited versions of systematic reviews, designed to provide a quick synthesis of evidence.
  • Less rigorous and robust than systematic reviews.
    • They should only be attempted when the subject matter is time-sensitive, such as an emerging disease or health crisis.
  • Less restrictive than systematic reviews.
  • Aim to map the available evidence on a particular topic.
  • Do not necessarily assess the quality of included studies.
  • Used to:
    • Identify gaps in the literature.
    • Clarify key concepts.
    • Understand the extent and nature of existing research.
  • a.k.a. overview or cumulative review
  • Summarize the findings from multiple systematic reviews and meta-analyses on related topics.
  • Provide higher-level synthesis of evidence.
  • Can offer broader insights into the overall strength and consistency of evidence across different research questions.
  • Focus on understanding how and why interventions work in specific contexts.
  • Particularly useful for complex interventions, in which the outcomes are influenced by various factors.
  • Combine qualitative and quantitative evidence synthesis.
  • Provide a comprehensive understanding of a research question.
  • Enables more holistic analysis of complex topics.