After choosing your research question—the first and most critical step in planning your systematic review—the next logical step is selecting the right type of systematic review. This decision will determine your review’s methodology, the types of studies you include, and how you ultimately synthesize the findings.
Selecting the correct type requires a clear understanding of the various systematic review types available. Each type is designed to answer specific kinds of research questions. Using the wrong type may lead to an ineffective synthesis and inaccurate conclusions.
Understanding the Types of Systematic Reviews
Before deciding on the appropriate type, it's essential to familiarize yourself with the different forms a systematic review can take. These include:
Qualitative systematic reviews
Systematic reviews of interventions
Diagnostic test accuracy reviews
Prognostic reviews
Scoping reviews
Methodological reviews
Umbrella reviews
Economic evaluations
Each of these has a distinct purpose and is aligned with particular types of research questions.
When to Use a Qualitative Systematic Review
If your research question aims to explore lived experiences, perceptions, attitudes, or social meanings, then a qualitative systematic review—also known as a qualitative evidence synthesis—is the best fit.
Example:
What are the experiences of transgender women in accessing pre-exposure prophylaxis (PrEP) in the United States?
This question seeks to understand lived experience, making a qualitative review appropriate.
When to Use a Systematic Review of Interventions
If your question aims to assess the effectiveness of an intervention—such as a treatment, program, or public health policy—a systematic review of interventions is required. These reviews often rely on randomized controlled trials (RCTs) but can include other study designs when necessary.
Example:
Does mindfulness-based stress reduction reduce anxiety among healthcare workers compared to no intervention?
This kind of question assesses effectiveness and therefore suits a systematic review of interventions.
When to Use a Diagnostic Test Accuracy Review
If you are examining how well a diagnostic tool or test identifies a condition compared to a gold standard, a diagnostic test accuracy (DTA) review is needed.
Example:
How accurate is the D-dimer test in diagnosing deep vein thrombosis compared to ultrasound?
This question focuses on diagnostic accuracy and thus warrants a DTA review.
When to Use a Prognostic Review
A prognostic review is ideal if your question focuses on predicting future outcomes or identifying prognostic factors that influence the course of a disease or condition.
Example:
What factors predict long-term functional recovery after stroke?
This type of question is focused on risk or protective factors and is best addressed through a prognostic review.
When to Use a Scoping Review
If your research question is broad or exploratory, aimed at mapping the evidence, identifying research gaps, or clarifying concepts, a scoping review is more suitable than a traditional systematic review.
Example:
What literature exists on the mental health of asylum seekers in Europe?
Because this question is broad, a scoping review is more appropriate.
When to Use a Methodological Review
If your aim is to evaluate or compare research methods, a methodological review is the best fit.
Example:
What methods have been used to measure quality of life in cancer survivors, and how reliable are they?
This is a methods-focused question, suitable for a methodological review.
When to Use an Umbrella Review
An umbrella review synthesizes findings from multiple existing systematic reviews. This type is useful when reviews already exist on similar interventions or outcomes.
Example:
What do existing systematic reviews say about digital interventions for smoking cessation?
Here, the goal is to summarize existing reviews rather than individual primary studies.
When to Use an Economic Evaluation
If your research question involves the cost-effectiveness or cost-benefit of an intervention, particularly in healthcare settings, an economic evaluation is appropriate.
Example:
Is colorectal cancer screening via colonoscopy cost-effective in low-income populations?
This type of question calls for an economic-focused review.
What About Meta-Analysis?
At this planning stage, you may wonder whether a meta-analysis is possible. It’s important to understand that meta-analysis is not a type of systematic review—it’s a statistical tool used to combine data from multiple studies.
Whether a meta-analysis can be conducted will depend on:
The availability of numerical outcome data
The consistency of outcome measures across studies
The similarity of study populations and methods
These factors can only be assessed after data extraction. So, while it’s helpful to consider the possibility of a meta-analysis, it should not dictate the type of review chosen at this point.
Final Thoughts
Choosing the right type of systematic review ensures that your research question is addressed using appropriate methods and that the synthesis is valid and useful. Always let your research question guide your decision. Are you exploring experiences, testing an intervention, or summarizing existing reviews? Knowing the difference—and choosing accordingly—sets your review up for success from the beginning.
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