EBM Dr Adrian Burger 20 March 2007

EBM Intro Evidence based guidelines Evidence based care paths Evidence based Questions Evidence based Solutions Evidence based ……

Shift_Expectations Whether to implement How to - sensibly - efficiently - avoid misconceptions EBM CONCEPTS ARE NOW UNAVOIDABLE

(Mis)Concepts EBM DOES NOT = RCT Cannot rely solely on research from RCT - <14% are RCT - Observational studies overlooked - undervalued patient preferences, clinical circumstances, expertise

What You Need to Do Clearly define your question Thorough literature search Critically appraise the quality of the evidence Critically assess the applicability Balanced application

The evidence cycle

Balanced application of the evidence

Clinical circumstances Clinical expertise and judgment Assumes physician competence on basis of - clinical experience - development of clinical instincts

Patient preferences Individualizes needs Takes into account patients’ - experiences - values - expectations

Research evidence Ask the question Acquire the information Appraise the quality Apply the results Act on the patient

EBM Resources Own research, reviews - Guide to the Medical Literature Online - Cochrane Database - Best Bets

Levels of Evidence Hierarchy of evidence RCT Controlled observational studies Uncontrolled studies and opinion

Studies: First Question Is the study - investigating results of a treatment? Therapeutic Study - outcome of a disease? Prognostic Study - Diagnostic test? - Developing an economic model/decision analysis?

Studies: Categorize the study Level 1 RCT or systematic review of RCTs Level 2 Prospective cohort, poor quality RCT, systematic review Level 3 Case control, retrospective cohort, systematic review of level 3 studies

Categorize the studies 2 Level 4 Case series Level 5 Expert opinion

Level One and Two

Level 3-5

Errors in Hypothesis Testing Small sample studies - Type 2 Beta errors Probability of concluding that no difference exists when there is a difference Acceptable rate is 20% This equals a power of 80% If >20% then unacceptably high risk of false negatives

Errors 2 Type 1 or Alpha Error Concluding the results of a study are true when in fact it is due to chance or random sampling error Is an erroneous false positive Acceptable rate of 5%

Power of a study Probability of concluding a difference between two treatments when one actually does exist Power = 1- Beta Can be used before a study to determine study sample size Can be used after a study to determine if negative findings true or just due to chance

Article Injury, 37, 302 – 306 Evidence-based Medicine: What it is and what it is not