The evidence-based approach to addressing questions concerning diagnosis, treatment, harm and prognosis (scroll down the glossary to find the alphabetical definition for prognosis) begins when the clinician faces a clinical dilemma. Once the problem has been identified, the next step (and often the most difficult step) is to formulate a structured clinical question in order to search the medical literature, and then to continue on to find the best relevant evidence from that body of literature.
Reference
Guyatt G, Meade MO. How to use the medical literature—and this book—to improve your patient care. Ch. 1. In: Guyatt G, Rennie D, Meade MO, Cook DJ, eds. Users’ Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice. 2nd ed. New York: McGraw-Hill; 2008. Available:
http://0-www.jamaevidence.com.innopac.wits.ac.za/content/3345000. [Accessed 25.07.2012]
Use the flowchart (available at the link below) in order to guide the process of finding the evidence.