"Good doctors use both individual clinical expertise and the best available external evidence, and neither alone is enough. Without clinical expertise, practice risks becoming tyrannized by evidence, for even excellent external evidence may be inapplicable to or inappropriate for an individual patient. Without current best evidence, practice risks becoming rapidly out of date, to the detriment of patients.“
-David L. Sackett
Professor Emeritus, Clinical Epidemiology & Biostatistics McMaster University
Haynes, RB. ACPJC Nov/Dec 2006;145(3):A8-9 Start at top and work your way down
Type of Question Suggested Best Type of Study Therapy RCT > cohort > case control > case series Diagnosis Prospective, blind comparison to gold standard Etiology / Harm RCT > cohort > case control > case series Prognosis Cohort study > case control > case series Prevention RCT > cohort study > case control > case series Clinical Exam Prospective, blind comparison to gold standard Cost Economic analysis Questions of therapy, etiology and prevention which can best be answered by RCT can also be answered by a meta-analysis or systematic review.
Evidence Pyramid Case Series/Case Reports Case Control Studies Cohort Studies Randomized Controlled Trial Systematic Review Meta-analysis Animal Research
Question: In hospitalized infants with bronchiolitis , does the use of nebulized hypertonic saline help to reduce symptoms and LOS? Type of question: Type of study: Therapy RCT > cohort > case control > case series In patient with [Patient/ Problem] does [Intervention] or [Comparison, if any] affect [Outcome]