Introduction to Evidence Based Medicine (EBM) Michael R. Kronenfeld, MLS, MBA Curt Bay, PHD

Evidence-Based Medicine What it is… Take a few moments and jot down what you think EBM is Why we need it… So, why do Physicians need EBM. Again, write down you own ideas. Maybe you think the profession doesn’t need EBM, if so, make sure you write down why.

Evidence-Based Medicine Definition Evidence-based medicine (EBM) is the integration of best research evidence with clinical expertise and patient values. …….. (continued in class textbook) Clinical Experience Patient’s needs, desires & values External Clinical Evidence

Why do Physicians need Evidence-based Medicine? The realizations, attested to by ever-increasing numbers of clinicians, are: our daily need for valid information about diagnosis, prognosis, therapy and prevention …… (again continued in class textbook) To put it into words again…..

Why do Physicians need Evidence-based Medicine? IOM report on quality

Years since graduation The Slippery Slope Knowledge of what is the current best care falls off every year after graduation... Knowledge of current best care One of the patterns that the authors noticed was that your basic knowledge (what you learned in school) goes downhill the longer you are from graduation. So how do you cope with this loss? Well, the other slide showed that PTs keep doing the same things they learned /thought they learned in school. This is called the slippery slope…. High . .. . . .... . r = -0.54 p<0.001 ... ... ... .. .... Low 1 10 Years since graduation

So What do Physicians use to make clinical decisions? 1. Tradition “I’ve always done it this way….” 2. Authority “Because “x” said so….” (the guru told me in the continuing ed. course….) 3. Intuition “It just seemed the thing to do.” 4. Trial & Error/Personal experience “If it works, I’ll use it.”

The Forest and the Trees 2 aspects of Evidence-Based Medicine in your clinical career: Maintaining your general level of knowledge – keeping up with new clinical developments and trends Being able to find the best evidence to assist you find the best answer for specific, patient focused questions

5 Step Model for EBP Asking answerable clinical question Searching for the evidence Critically appraising the evidence Validity Relevance Making a decision Integrating evidence with expertise and patient’s values Evaluating your performance

How we might make decisions Which Intervention Should we select? A or B Instead of relying on tradition, the way I’ve always done it, etc or the way we recall it occurred--it would be better for our pts, for our profession if we used evidence as rationale for our decisions. Wouldn’t it be better if we could say: I will do this test to evaluate my patient because I know it is reliable, it is valid, and it will give me the most information (bang for the buck) as opposed to test B? , and the same can be said for selecting our interventions---based on evidence…. If we knew the….. Outcomes of A Outcomes of B Knowledge of: Risks & Benefits A Risks & Benefits B and the A B

What is meant by ‘evidence’? Originators of EBP refer to a “hierarchy” of evidence as illustrated with the EBM Pyramid At the top: well designed research studies suitable for the question (randomized controlled trials=RCT) Not all studies are well designed Different study designs suit different questions At the bottom: expert opinion (including articles by experts giving their opinion) plus other research

Levels of Evidence Pyramid

Levels of Evidence - Therapy/Prevention, Etiology/Harm 1a SR (with homogeneity*) of RCTs 1b Individual RCT (with narrow Confidence Interval‡) 1c All or none§ 2a SR (with homogeneity*) of cohort studies 2b Individual cohort study (including low quality RCT; e.g., <80% follow-up) 2c "Outcomes" Research; Ecological studies 3a SR (with homogeneity*) of case-control studies 3b Individual Case-Control Study 4 Case-series (and poor quality cohort and case-control studies§§) 5 Expert opinion without explicit critical appraisal, or based on physiology, bench research or "first principles" Note – Full table located at CEBM – Enter for Evidence-based Medicine at http://www.cebm.net/index.aspx?o=1025

5 S Pyramid In recent years a new EBM pyramid has expanded beyond the original one reflecting new formats for aggregating and presenting evidence which have developed more relevant to point of care application

Types of Clinical Questions Clinical questions usually fall into one of four main categories: Etiology / Harm : identifying associations, risk factors and causes of a disease Diagnosis: selecting tests that accurately detect a disease Therapy / Prevention : selecting effective interventions to treat or prevent a disease Prognosis: predicting the probable outcome of a disease or treatment

Sample questions: Etiology / Harm : Do the standard, childhood vaccinations increase the risk of autism? Diagnosis: What is the best method to evaluate a patient with an irregular heart beat? Therapy / Prevention : In a patient with HDL and high cholesterol will changing diet and increasing exercise affect the development of CHD? Prognosis: What is the probability of a full recovery for a patient with community acquire pneumonia?

What Studies for Which Clinical Questions?? Type Of Question Type of Study Clinical Examination Prospective, blind comparison to gold standard Diagnostic Testing Prognosis Cohort Study > Case Control > Case Series Therapy RCT is the only way to answer these questions Etiology / Harm Prevention RCT > Cohort Study > Case Control > Case Series

Step 1 - EBM starts with a question… A questions occurs…. In reference to clinical management or specific treatments About advice/information to give About development of a service About an educational strategy to use And a knowledge gap

Background / Foreground Questions

Background questions can also be thought of as having levels/steps Background questions can also be thought of as having levels/steps. The lowest level is 1 and often begins with the stem “what is/what are” are occurs when you don’t know a lot about the disorder (see Fig 1.1 on the CD); you are trying to identify factors associated with the patient’s problem. Level 2 is the intermediate level. Level 2 questions begin with the stem “what is the relationship between” ; for level 2 questions, the factors have already been identified, but you are trying to determine their relationship. Finally, the highest of the background questions is level 3 and begins with the stem, “why does or how does” and looks for causality. Often times, level 3 questions are answered by physiological/bench research studies. While Level 1, 2 and 3 questions are good questions, when you want to find studies that present information about clinical outcomes, EBP uses another way to build an answerable question. The mnemonic is PICO. Patient/Problem-Intervention-Comparison-Outcome. Although there are nearly a dozen issues related to questions (Table1.2-CD), most often in PT, PICOs question are built to address: diagnosis/differential diagnosis, prognosis, intervention.

Asking Answerable Questions - Foreground Patient or Problem Intervention Comparison intervention (if appropriate) Outcome(s) P- I- C- O Asking a P-I-C-O question encourages foreground questions.

Asking An Answerable Question The Components Element Tips Example Start with your patient, ask "How would I describe a groups of patients similar to mine?" In middle age adults who have had an uncomplicated MI Patient/ Problem Would a phase II supervised, hospital-based cardiac rehab program "Which main intervention am I considering? Intervention Comparison Intervention "What is the main alternative intervention?" Be better than a home-based exercise program In improving this patient's cardiovascular capacity (peak VO2) and return to work? Outcome "What do I hope to change?"

Evidence-Based Medicine What it is… Take a few moments and jot down what you think EBD is Why we need it… So, why do Physicians need EBM? Again, write down you own ideas. Maybe you think the profession doesn’t need EBM, if so, make sure you write down why.