DEPARTMENT OF FAMILY AND COMMUNITY MEDICINE UP-PHILIPPINE GENERAL HOSPITAL INTRODUCTION TO EVIDENCE-BASED MEDICINE

OBJECTIVES 1. To define Evidence Based-Medicine Family and Community Practice (EBMFCP) 2. To discuss the uses (importance) of EBMFCP 3. To discuss the foundations of a clinical dilemma (clinical question) based on a patient’s case scenario 4. To discuss the different strategies in searching for answers 5. To discuss the steps regarding the critical appraisal of a journal

Introduction Medicine is not an exact science. Medicine is a dynamic field of knowledge. Problems ariseNew information regarding therapeutics and diagnosticsAffect patient managementQuality of care changes

In our day to day encounter with patients we often find ourselves facing a dilemma or questions in regard to: Therapeutics Diagnostics Differential diagnoses Prognosis Harm

Diagnosis How to select and interpret the appropriate diagnostic tests Therapy How to select treatments to offer patients that do more good than harm and that are worth the efforts and costs of using them Prognosis How to estimate the patient’s likely clinical course over time and anticipate likely complications of disease Harm/Etiology How to identify causes for the disease (including iatrogenic forms)

 Patients usually serve as the starting point  Good questions are the backbone of EBM  Searching for the right answers is usually the hardest step.

RESOLUTION OF THE CLINICAL DILEMMA

Looking for answers The usual thing………… When asked or in doubt, > we get it from books and journals > ask other: friends, colleagues, mentors, subspecialty experts However,

OUR INFORMATION NEEDS ARE NOT MET!!!  our textbooks are out of date by the day they are published  our journals are disorganized and inaccessible to us  our colleagues may not have the answers that we seek

Evidence Based Medicine New Paradigm Search for the CURRENT BEST EVIDENCE Appraise Decide and Apply Evaluate

WHAT IS EBM? “ The conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research." Dr. David Sackett, 1996

EBM is a systematic approach  ACQUISITION  APPRAISAL  APPLICATION of Research to guide decisions in health care

ADVANTAGES OF EBFCP TO DOCTORS:  Lifelong learning  Continuing professional development  Keeping up to date

 Better quality of care  Cost-effective care  Better outcomes TO PATIENTS:

TO THE HEALTH CARE SYSTEM : Better utilization of healthcare resources

The Evidence-Based Family and Community Practitioner Clinical Experience Patient Values Evidence DECISION

Ask Acquire Appraise Apply Act & Assess Patient dilemma Principles of evidence-based practice Evidence alone does not decide – combine with other knowledge and values Hierarchy of evidence Process of EBP

Steps in the EBM Process

CLINICAL SCENARIO Maria, 50/F History of CHF 2o to several Myocardial Infarctions Hospitalized 2x w/n the last 6 months due to worsening of heart failure

Normal sinus rhythm presently Enalapril, aspirin and simvastatin Wants desperately to stay out of the hospital Digoxin (?)

CLINICAL SCENARIO You think she should also be taking digoxin but you arent certain if this will help keep her out of the hospital. You decide to research this question before her next visit.

Background Questions: Ask for general knowledge about a disease or disease process, tests, treatments, etc.  2 components:  a. root* + verb “What causes….”  b. condition …. SARS?” * Who, What, Where, When, How, Why Usually asked because of the need for basic information. Answering the background question. textbooks, handbooks and databasestextbooks handbooks and databases

Foreground Question: About patient care decisions and actions  4 (or 3) components:  a. Patient, problem or population  b. intervention, exposure, or manuever  c. comparison (if relevant)  d. clinical outcomes (including time horizon) e.g: in young children with acute otitis media, is short-term antibiotic therapy as effective as long term antibiotic therapy?

Formulating a Focused Question Population (P) – general characteristics of the group of subjects in question Intervention(I) – drug or treatment, diagnostic test, risk factor or anything that is being tested Outcome (O) – endpoint against which a certain intervention is measured Methodology (M) – study design

Translate dilemmas into questions Keep the questions simple, relevant, and manageable Complex questions: FRUSTRATION!! Patient/problemCongestive heart failure, elderly InterventionDigoxin Comparison, if anyNone, placebo OutcomePrimary:reduce need for hospitalization Secondary: reduce mortality

The question: In elderly patients with congestive heart failure, is digoxin effective in reducing the need for rehospitalization?

THE SEARCH Identify key terms Use the boolean principle (Venn diagram) in combining terms Use OR to broaden search Use AND to narrow down search Use of “Quotation Marks” Use of the MeSH Use of limits Use of truncations

The Key Terms Population – elderly hypertensives with CHF Intervention – digoxin Outcome – rate of hospitalization Methodology – RCT In elderly patients with congestive heart failure, is digoxin effective in reducing the need for rehospitalization?

The Boolean Principle Congestive Heart Failure Digoxin Hospitalization OR to broaden search AND to narrow down search

The Evidence Pyramid Meta-Analysis Systematic Review Randomized Controlled Trial Cohort Studies Case-Control Studies Case Series/Case Report Animal Research/Laboratory Studies

Type of Question Suggested Best Type of Study TherapyRCT > Cohort > Case-Control > Case Series DiagnosticProspective, blind comparison to a gold standard Etiology/HarmRCT > Cohort > Case-Control > Case Series PrognosisCohort > Case Control > Case Series

WHAT TO ACCESS?

What do we do with our output? When you have the article, appraise it using the Evidence-Based Family and Community Practice and Quality Improvement in Health Care Manual (FMRG, 2003) Weigh the evidence afforded by the article

EVIDENCE-BASED FAMILY AND COMMUNITY PRACTICE I. Is it relevant? II. Is it valid? III. What are the results? IV. Is it applicable to my patient?

JOURNAL REPORT FORMAT  Case Scenario  Research Question  Search  Title  Source  Authors  Appraisal

CRITICAL APPRAISAL OF AN ARTICLE ON THERAPEUTICS

CRITICAL APPRAISAL OF AN ARTICLE ON THERAPEUTICS I. Is it relevant? Is the objective of the study similar to your clinical dilemma?  population of the study  intervention and comparative interventions  outcome of the study

2. Was follow-up complete? Methodology and Result Section Look at the number of patients enrolled at the outset and compare this with the number of patients reported in the results table A drop-out rate of 20% or more is usually declared substantial, if otherwise, check whether an intention to treat analysis was done. What is the drop-out rate?

Secondary Guides: 1. Was the study blinded? What is the definition and importance of blinding? Look at the methodology and results section. Single Blinding? Double Blinding? Triple Blinding?

2. Were the outcome measurements clearly described and determined in the same way between interventions? whether the outcome measures are those which you and your patient are interested in Surrogate outcome? Clinical outcomes?

Overall, is the study valid?

III. What are the results? A. How large was the treatment effect? Risk in Control (Rc): Risk in Treatment (Rt): No. pxs who did not get well in the control Total no. of pxs in the control group No. who did not get well in the txt group Total no. pxs in the treatment group

Absolute Risk Reduction (ARR) = Rc - Rt Relative Risk (RR) = Rt/Rc RR of 1 : No difference between Treatment and Control RR of >1: Treatment is more harmful RR of <1: Treatment is more effective Relative Risk Reduction (RRR) = 1 – RR

B. Are the results reliable?  What is the confidence interval?  What is the p-value?

IV. Are the Results Applicable to My Patient? Are the medical, social and economic resources needed to administer the treatment available in your setting? In your perception, were the treatment and its outcome as measured in the article preferred by the patient and his family? Do you think that the patient, family, and/or community will be willing to accept and pay for the treatment in question? Number Needed to Treat = 1/ARR Cost-Effectiveness Formula: NNT x price/unit x dose x duration

RESOLUTION OF THE THERAPEUTIC DILEMMA

CRITICAL APPRAISAL OF AN ARTICLE ON DIAGNOSTICS

The Decision Analysis - Establish Diagnostic and therapeutic thresholds Diagnostic Threshold (DT): arbitrary point at which you rule out the disease Therapeutic Threshold (TT): arbitrary point at which you decide to treat - Determine other parameters Pre-test Probability: probability that the patient has the disease Post-test Probability: probability that the patient has the disease after doing the diagnostic exam DTTT.501

Search Appraise DETERMINE THE POST- TEST PROBABILITY

CRITICAL APPRAISAL OF AN ARTICLE ON DIAGNOSTICS I. Is it relevant? Is the objective of the study similar to your clinical dilemma? - population of the study - intervention and comparative interventions - outcome of the study

Primary Validity Guides:  Is it valid?  Was there a comparison with a reference standard?  Whether the reference standard was done regardless of the results of the diagnostic test  Meaning of reference standard? Precision? Accuracy?

CRITICAL APPRAISAL OF AN ARTICLE ON DIAGNOSTICS II. Is it valid? 2. Did the patient sample include an appropriate spectrum of patients on whom the test will be used?

Representativeness includes subjects with the whole spectrum of the disease. -Exclusion and Inclusion Criteria The accuracy of a diagnostic test among patients with low risk for the disease is different from patients with high risk for the disease.

2. 3. Was the reading or interpretation of the diagnostic test and reference standard done independently? Presence of blinding Evaluates the performance of the diagnostic test independently Avoids bias

 4. Was the diagnostic test and reference standard described in detail to permit replication? Clear procedures including preparation of subjects  Diet, Drugs to avoid, precautions  Step by step descriptions Be able to duplicate the test and get the same outcome. Look at the “results and methodology” section

III. What are the results? What are the likelihood ratios for the different test results? - Sensitivity and Specificity - Likelihood Ratios - Pre and Post Test Probabilities

Recall: Sensitivity and Specificity PresentAbsent PositiveTPFP NegativeFNTN Disease Test Sensitivity: probability/likelihood that the diseased patient will test positive Specificity: probability/likelihood that those without the disease will test negative TP/TP+FN TN/TN+FP

Presumptions: Pre-test probabilities will have a profound effect on the post-test probability Diagnostic tests provide more information when the diagnosis is truly uncertain than when the diagnosis is either unlikely or truly certain. - if results of the test could shift the probability of the disease across the treatment threshold

- Using likelihood ratios - Using likelihood ratios and a nomogram Post-test Probability Estimates make quick assessment of the usefulness of a contemplated diagnostic test.

Likelihood ratios - Uses sensitivity and specificity values - utilizes the 2 x 2 contingency table Probability of result in diseased persons Probability of result in non-diseased persons Every test has two likelihood ratios: LR (+) and LR (-) LR (+) : Probability that test is + among diseased persons Probability that test is + among non-diseased persons Sensitivity 1- Specificity

LR (-) : Probability that test is - among diseased persons Probability that test is - among non-diseased persons 1-Sensitivity Specificity

Using likelihood ratios and a nomogram Establish pre-test probabilities Calculate the LR Plot

Search Appraise DETERMINE THE POST-TEST PROBABILITY The Decision Making Line DT TT TREAT!!!Don’t start treatment!

IV. Can the Results Help Me in Caring for My Patient? 1. Will the reproducibility of the test result and the interpretation be satisfactory in my setting? 2. Are the results applicable to my patient? 3. Will the result change my management?

RESOLUTION OF THE DIAGNOSTIC DILEMMA

Sources: EBM ’08 edition UP-PGH DFCM

THANK YoU! The doctor of the future will give no medicine, but will interest her or his patients in the care of the human frame, in a proper diet, and in the cause and prevention of disease. Thomas A. Edison US inventor ( )