Evidence Based Medicine 2019 A.Bornstein MD FACC Assistant Professor of Medicine Hofstra Northwell School of Medicine Hempstead, Long Island

Evidence Based Medicine: Levels of Evidence

History of EBM The Term Evidence Based Medicine was first coined by a team at M c Master University in Canada led by Gordon Guyatt in 1992 The Term Evidence Based Medicine was first coined by a team at M c Master University in Canada led by Gordon Guyatt in 1992 The term Evidence Based Health Care appeared later in the decade noting that the approach was appropriate to health professionals other than MDs The term Evidence Based Health Care appeared later in the decade noting that the approach was appropriate to health professionals other than MDs Evidence Based Practice is the term used now indicating that professions outside medicine are becoming involved also Evidence Based Practice is the term used now indicating that professions outside medicine are becoming involved also

Evidence Based Medicine ? 1)The increasingly fashionable tendency of a group of young, confident, and highly numerate medical academics to belittle the performance of experienced clinicians using a combination of epidemiological jargon and statistical sleight of hand. 2)The argument, usually presented with near evangelistic zeal, that no health related action should ever be taken by a doctor, nurse, health professional, or politician, unless and until the results of several large and expensive research trials have appeared in print and been approved by a committee of experts! 3)EBM seems to replace original findings with subjectively selected, arbitrarily summarized, laundered, and biased conclusions of indeterminate validity or completeness, carried out by people of unknown ability, experience, and skills using methods whose opacity prevents assessment of the original data

Evidence Based Medicine ! 4)The conscientious and judicious use of current best evidence in making decisions about the care of individual patients; the practice of EBM means integrating, individual clinical expertise, patient values & preferences with the best available external clinical evidence from systematic research 5)The process of life-long self directed learning in which caring for patients leads to the search for, critical appraisal of, and incorporation into practice of, valid and clinically important information about diagnosis, prognosis, therapy and other clinical and health care issues 6)Just in time learning (? Prof Jeremy Clarkson Feb 2009 ?)

EBM Triad

Practicing the 5 Stages of Evidence Based Medicine 1)Convert the need for information into an answerable question (PICO) 2)Find the best available evidence with which to answer that question (searching the most appropriate literature [?]) 3)Appraise critically that evidence for validity (closeness to the truth), importance (effect size) & applicability (in one’s own practice) 4)Integrate the critical appraisal with one’s own expertise, the patient’s unique biology, values and circumstances 5)Evaluate one’s effectiveness & efficiency in executing steps 1-4 and seeking ways to improve them

Evidence Based Medicine How should we address this most effectively? How should we address this most effectively? What are we going to do? What are we going to do? – How to formulate a clinical question (PICO) – Some basic calculations used in EBM

PICO Population Population Intervention Intervention Comparator Comparator Outcome Outcome

PICO P – patients with COPD (patient population) P – patients with COPD (patient population) I – does inhaled Tiotropium (intervention) I – does inhaled Tiotropium (intervention) C – compared to placebo (active comparator or current standard of care) C – compared to placebo (active comparator or current standard of care) O – result in a decrease in the rate of decline of FEV 1 (outcome) O – result in a decrease in the rate of decline of FEV 1 (outcome) UPLIFT study UPLIFT study

PICO – How Does It Help? Usefulness Usefulness – When appraising a paper – When thinking about a problem to which you may need to try and find the answer, it helps one formulate a clinical question, so that you can identify key words for a literature search

Basic Statistics Relative Risk (RR) Relative Risk (RR) Relative Risk Reduction (RRR) Relative Risk Reduction (RRR) Absolute Risk Reduction (ARR) Absolute Risk Reduction (ARR) Number Needed to Treat (NNT) Number Needed to Treat (NNT)

Imagine a Clinical Trial Formulating a clinical question: Formulating a clinical question: 1)Population – in healthy GP Registrars 2)Intervention – does taking a vitamin B supplement 3)Comparator – compared to placebo 4)Outcome – result in reduced failure rates for GP Registrars of the Royal College of General Practitioners (nMRCGP)?

Vitamin B and GP Registrars of the Royal College of General Practitioners (nMRCGP) Recruit 1000 GP registrars Recruit 1000 GP registrars Randomly allocate 500 to vitamin B for 3 years Randomly allocate 500 to vitamin B for 3 years Randomly allocate 500 to placebo for 3 years Randomly allocate 500 to placebo for 3 years After 3 years you measure failure rate for nMRCGP in both groups After 3 years you measure failure rate for nMRCGP in both groups

Vitamin B and nMRCGP Results Results – Placebo group failed CER (Control Event Rate) = 100 out of 500 or 20% CER (Control Event Rate) = 100 out of 500 or 20% – Vitamin B group - 20 failed EER (Experimental Event Rate) = 25 out of 500 or 5 % EER (Experimental Event Rate) = 25 out of 500 or 5 %

Definitions RR is EER/CER (CER = Control Event Rate) & EER (Experimental Event Rate) RR is EER/CER (CER = Control Event Rate) & EER (Experimental Event Rate) ARR is CER – EER % (ARR = Absolute Risk Reduction) ARR is CER – EER % (ARR = Absolute Risk Reduction) RRR is [(CER – EER)/CER] x 100 % (RRR = Relative Risk Reduction) RRR is [(CER – EER)/CER] x 100 % (RRR = Relative Risk Reduction) NNT is 100/ARR (NNT = Number Needed to Treat) NNT is 100/ARR (NNT = Number Needed to Treat)

Trial Results Results Placebo group 100 failed – CER = 100 out of 500 or 20% Vitamin B group 20 failed – EER = 25 out of 500 or 5% RR, RRR, ARR, NNT Relative Risk (RR) of the outcome is – EER / CER = 5 / 20 = 0.25 – 25% Relative Risk Reduction (RRR) is – (CER – EER) / CER X 100 or 15/20 x 100 = 75% Absolute risk reduction (ARR) is CER – EER = 15% NNT is 100 / ARR (100 / (20 – 5) =  7 Need to treat 7 GP registrars for 3 years with vitamin B to achieve 1 less failure in nMRCGP

Summary RR is EER/CER RR is EER/CER ARR is CER – EER ARR is CER – EER RRR is (CER – EER)/CER RRR is (CER – EER)/CER NNT is 100/ARR NNT is 100/ARR

Task 8 randomized controlled clinical trials 8 randomized controlled clinical trials Write down the following Write down the following – In PICO style, what was the clinical question addressed by the study – Calculate for the specified outcome only the following: CER CER EER EER RR RR RRR RRR ARR ARR NNT for duration of study NNT for duration of study NNT for 1 year NNT for 1 year

RR, RRR, ARI, and NNT Relative Risk (Risk Ratio) of the outcome is Relative Risk (Risk Ratio) of the outcome is – EER/CER = 5/20 = 0.25 (aka risk ratio or rate ratio) Relative Risk Reduction (RRR) is Relative Risk Reduction (RRR) is – {(CER – EER)/CER} X 100 or 15/20 x 100 = 75% Absolute risk reduction (ARR) is CER – EER = 15% Absolute risk reduction (ARR) is CER – EER = 15% NNT is 100/ARR (expressed as a percentage) NNT is 100/ARR (expressed as a percentage) NNT = 7 or you need to treat 7 healthy GP registrars for 3 years with vitamin B to achieve 1 less failure in nMRCGP NNT = 7 or you need to treat 7 healthy GP registrars for 3 years with vitamin B to achieve 1 less failure in nMRCGP