Presentation on theme: "Sue McGuinness, PhD, MLS Karen Heskett, MSI Alice Witkowski, MLS"— Presentation transcript:
1Medical Education Development Series: Specialty Resources and Tools for the Clinician Sue McGuinness, PhD, MLSKaren Heskett, MSIAlice Witkowski, MLSFebruary 8, 2007
2Learning OutcomesUnderstand basic principles of Evidence- Based Medicine (EBM)Be aware of EBM and Drug information ToolsPractice Using EBM and Drug Information Tools
3Evidence-Based Medicine What Is It?Clinical Expertise + conscientious, judicious use of the best available evidence in making decisions about patient careExpertisePatient valuesEvidence
4Evidence-Based Medicine Why practice it?Dispel “myths”Deal with information overloadAids decision makingImproves patient careWhy teach it?AAMC learning objectivesImproves critical thinking skillsCan apply to clerkships, residencies, rounds, PBL courses, reading groups, journal clubs,
5Barriers to practicing EBM TimeInformation ResourcesCost
6Analysis of questions asked by family doctors regarding patient care Ely JW, et al. BMJ 1999;319:
7Physicians’ Information Needs Ely JW, Osheroff JA, Chambliss ML, Ebell MH, Rosenbaum ME JAMIA 12 (2): MAR-APR 2005Total QuestionsN=1,062PursuedN= 585 (55%)Not PursuedN= 477 (45%)Answered, no difficultyN=238 (41%)Answered with difficultyN=180 (31%)Not AnsweredN=167 (28%)Why? Limited time, Suspect lack of information, Need better resources.
8How to practice EBM (The 5 A’s) Assess- patient history, labs, meds, patient values* Ask- build a focused searchable question* Acquire- the best evidence you can findAppraise- evaluate the evidenceApply- to patient care
9Categories of Clinical Questions Diagnosis – Test A or B to differentiate between positive an negativeTherapy – treatment A or B to improve a condition or avoid an adverse eventPrognosis – future course of condition or diseaseEtiology/harm- effects of agents on function, morbidity, mortality
10Hierarchy of Evidence Systematic Reviews & Randomized Controlled Meta-analyses of RCTsRandomized ControlledTrials (RCTs)Systematic Reviews ofObservational StudiesRetrospective (case-control)Prospective (cohort)Case SeriesCase Reports
11Best Evidence for Clinical Questions Diagnosis and Therapy- randomized controlled trialEligible patientsPrognosis and Etiology/Harm- observational studiesoutcomerandomizationtreatmentplacebooutcomeoutcomeCircumstancesexposednot exposedEligible patientsNo outcome
12Ask: Formulating the well- built clinical question Pauline is a new patient who recently moved to the area to be closer to her son and his family. She is 67 years old and has a history of congestive heart failure brought on by several myocardial infarctions.She has been hospitalized twice within the last 6 months for worsening of heart failure. At the present time she remains in normal sinus rhythm. She is extremely diligent about taking her medications (enalapril, aspirin and simvastatin) and wants desperately to stay out of the hospital. You think she should also be taking digoxin but you are not certain if this will help keep her out of the hospital. You decide to research this question before her next visit.Introduction to Evidence-Based Medicine [online tutorial] Duke University Medical Center Library, UNC-\Chapel Hill health Sciences Library,Accessed 2/6/07
13Ask: Build a focused query (PICO) P: terms describing the patient/problemI: terms describing the interventionC: list any alternative interventionsO: terms defining the outcome of interestDo not need PICO for pre-filtered systematic reviewsor meta-analyses
14ASK: Focused query Patient / Problem Intervention Comparison Outcome congestive heart failure, elderlydigoxinnone, placeboprimary: reduce need forhospitalizationsecondary: reduce mortality
15The well-built clinical question In elderly patients with congestive heart failure, is digoxin effective in reducing the need for hospitalization?It is a therapy question:The best evidence would be a a systematic review or meta-analysis. If we couldn’t find one then look for randomized controlled trial (RCT).
16Acquire: Know the resources (ask a librarian!) Find the best available evidenceStarting with PubMed
17Acquire: Finding the best evidence in MedLine/PubMed: Therapy Questions PICO using MeSH terms where availableLimit to meta-analyses OR randomized controlled trials OR clinical trials
20The effect of digoxin on mortality and morbidity in patients with heart failure. The Digitalis Investigation Group. New England Journal of Medicine February 20, 1997; 336(8):
21Therapy Question: Appraise Are the results valid?What do the results mean? (are they important?)
22Appraise: validity questions for therapy articles Were patients randomized?Was randomization concealed?Were patients in experimental and control groups similar interms of prognostic factors?Was follow up complete?Answers: Article: This study methodology appears to besound and the results are valid.
23Appraise: Part 2- are the results important? OutcomePlaceboDigoxinHospitalization due to CHF35%27%
24Appraise: Are the results important Appraise: Are the results important? Ways to quantify magnitude of treatment effectRelative Risk: Risk of the outcome in experimental groupcompared to the risk in the control group. .RR= outcome (exp) / outcome (con)= 27/35= .77 = 77%Relative Risk Reduction: The percent reduction ofrisk in the experimental group compared to the control group)RRR = outcome (con) – outcome (exp) / outcome (con)= 23%
25Appraise…Are the results important Absolute Risk Reduction: The difference between outcome rates in experimental and control groupsARR= outcome (con) – outcome (exp)Example: 35% - 27% = 8%100%65% avoid the hospital either way8% avoid the hospital by taking digoxin27% are hospitalized either way
26Appraise: Ways to quantify effect Number needed to treat (NNT): The number of patients that need to be treated to observe outcome in one patient.Example ARR = 8%Outcome (death) was avoided 8 times per 100 patients.How many patients need to be treated in order to avoid one death? 8/100 = 1/NNTNNT = 100% / ARR % = 100/8 = 13 patients need to be treated in order to avoid one hospitalization by using digoxin
27RRR vs. ARR: Some papers report RRR only. Why is that a problem? Calculate RRR, ARR and NNT for the following three RCTs% MortalityTreatmentControlRCT 11015RCT 24060RCT 390
30Diagnosis Questions Ask (PICO) Acquire (Systematic reviews, metaanalyses, RCTs)Appraise (Validity and Importance)Validity questions differ for diagnosisData are different (sensitivity, specificity, likelihood ratios)Evidence-Based Medicine: How to practice and Teach EBM, Sackett DL, et al. NY: Churchill, 2000.
31Diagnosis: Validity questions Key issues for Diagnostic Studies:blindingidentified gold standard testpatient sampleeach patient gets both tests
32Diagnosis: Are the results important Sensitivity measures the proportion of patients with the disease who also test positive for the disease.Specificity measures the proportion of patients without the disease who also test negative for the disease.
33Search Tip for Diagnosis Use the MeSH term “Sensitivity and Specificity”If that doesn’t work, use ONE of the terms in your search
37Drug Information Questions Now that we’re giving Digoxin to Pauline, we need information on adverse effects, interactions with other drugs or foods, dosing information, and information for Pauline to read about her new medication.
38Drug Information Resources Clinical PharmacologyMicromedex
39Exercises: work in groups, pick a question Fred: TherapyAmelia: TherapyMyrtle: DiagnosisAny questions you have had in your practiceASKACQUIREAppraise, if you have time. Validity questions are in your packet