P: Patient, Problem or Population
What are the characteristics of the patients or population?
I: Intervention
What intervention are you considering (medical, surgical, preventative)?
C: Comparison
What is the alternative being considered, if any?
O: Outcome
What is the estimated clinical outcome?
T: Time
What is the time period?
Background questions are foundational questions about a clinical issue, for example, what is cancer cachexia (progressive body wasting), and what is its pathophysiology? Answers to such questions are typically found in textbooks.
Foreground questions, by contrast, are those that can be answered based on current best research evidence on diagnosing, assessing or treating patients, or on understanding the meaning or prognosis of their health problems.
Source:
Polit, D., & Beck, C.T. (2014) Essentials of nursing research: Appraising evidence for nursing practice (p. 29). Philadelphia: Wolters Kluwer Health /Lippincott Williams & Wilkins.
From Bodleian Library at the University of Oxford