PICO is one type of framework to develop an evidence based practice literature search strategies.
The acronym stands for:
P - Patient, Problem, or Population (What is the condition or disease?)
I - Intervention (What do you want to do with this patient?)
C - Comparison, or Control, or Comparator (What is the alternative to the intervention?)
O - Outcome (What are the relevant outcomes?)
By using this framework you are able to structure a well-formed clinical search question.
Kloda LA., Bartlett JC (2014) Formulating Answerable Questions: Question Negotiation in Evidence-based Practice. Journal of the Canadian Health Libraries Association / Journal De L’Association Des Bibliothèques De La Santé Du Canada, 34(2), 55-60.