Before you can apply evidence to your patient, you need to undertake a thorough appraisal. The four questions below are from the Centre for Evidence Based Medicine (CEBM) at Oxford University. These provide a good starting point for appraising any clinical question.
"Critical appraisal is the systematic evaluation of clinical research papers in order to establish:
From: Centre for Evidence Based Medicine (CEBM) http://www.cebm.net/critical-appraisal/
from JAMA: Users' Guides to the Medical Literature. Evidence-Based Medicine Working Group