More than in every other search, Systematic Review requires a " literature for inclusion" search. This means that it is highly advisable to ensure a well formulated and specific research question as the basis of the process. If your search question is too broad you will be overwhelmed with results and never be able to sift through all of them. If you haven't searched for similar topics by other authors to see how they have referred to the same concepts and what terminology they have used, then you may miss relevant papers. If you haven't broken your search question down into separate concepts to have a clear view of the main terms, it will be difficult to search the databases effectively and to appropriately combine your search terms.
Identify your research question
Think of it as an in-depth attempt to answer a specific, focused question in a systematic way
You can use a research framework to help structure your research and ensure you have clear parameters for your search. The PICO (Patient, Intervention, Comparison, Outcome) framework is commonly used to develop focused clinical questions for quantitative systematic reviews.
A good PICO will
PICO's elements represent different concepts and will guide you while framing your question:
P – Patient | Population
Most important characteristics of patients. Examples: Gender, age, and disease or condition
I – Intervention or exposure
Main intervention. Examples: Drug treatment, diagnostic and screening test
C – Comparison or control
Main alternative. Examples: Standard therapy, placebo, no treatment, and a gold standard
O – Outcome
What you are trying to accomplish, improve, measure, affect. Examples: Reduced mortality or morbidity, and improved memory
While PICO is a helpful framework for clinical research questions, it may not be the best choice for other types of research questions, especially outside the health sciences. Here are a few others (for a comprehensive, but concise, overview of the almost 40 different types of research question frameworks, see this review from the British Medical Journal: Rapid review of existing question formulation frameworks)
Example: What are the experiences (phenomenon of interest) of caregivers providing home based care to patients with Alzheimer's disease (population) in Australia (context)?
P Perspective (for whom)
Example: What are the benefits (evaluation) of a doula (intervention) for low income mothers (perspective) in the developed world (setting) compared to no support (comparison)?
PI Phenomenon of Interest
R Study Type
Example: What are the experiences (evaluation) of women (sample) undergoing IVF treatment (phenomenon of interest) as assessed?
Design: questionnaire or survey or interview
Study Type: qualitative or mixed method
Developing your research question is one of the most important steps in the evidence synthesis process. At this stage in the process, you and your team have identified a knowledge gap in your field and are aiming to answer a specific question:
OR assess an intervention:
OR synthesize the existing evidence
Whatever your aim, formulating a clear, well-defined research question of appropriate scope is key to a successful evidence synthesis. The research question will be the foundation of your synthesis and from it your research team will identify 2-5 possible search concepts. These search concepts will later be used in step 5 to build your search strategy.