The first step in the systematic review process is to create a focused, well-defined research question. The question needs to be structured using a framework such as PICO which stands for Patient, Intervention, Comparison, and Outcome. There are many other frameworks available, use the best one to fit your topic.
PICO is a mnemonic used to describe the four elements of a good clinical question. It stands for:
P - Patient/Problem/Population
I - Intervention
C - Comparison
O - Outcome
(T) - Time (when applicable)
For Diagnosis, you may consider using:
P - Patient
I - Test
C - Standard
O - Outcome
For Prognosis, an alternative could be:
P- Patient
I - Prognostic Factors
C - Absence of Prognostic Factor
O - Outcome (ex. Mortality)
For Risk/etiology/harm
P- Patient
I - Risk Factor
C - Absence of Risk Factor
O - Outcome
Here are links for more information.
Before starting your search, make sure that someone else has not already done the same or similar work. Check PubMed, Google Scholar, and PROSPERO, the international prospective register of protocols for systematic reviews, before your search.