Presentation on theme: "Medical Education Development Series: Specialty Resources and Tools for the Clinician Sue McGuinness, PhD, MLS Karen Heskett, MSI Alice Witkowski, MLS."— Presentation transcript:
Medical Education Development Series: Specialty Resources and Tools for the Clinician Sue McGuinness, PhD, MLS Karen Heskett, MSI Alice Witkowski, MLS February 8, 2007
Learning Outcomes Understand basic principles of Evidence- Based Medicine (EBM) Be aware of EBM and Drug information Tools Practice Using EBM and Drug Information Tools
Evidence-Based Medicine What Is It? Clinical Expertise + conscientious, judicious use of the best available evidence in making decisions about patient care Expertise Patient values Evidence
Evidence-Based Medicine Why practice it? –Dispel “myths” –Deal with information overload –Aids decision making –Improves patient care Why teach it? –AAMC learning objectives –Improves critical thinking skills –Can apply to clerkships, residencies, rounds, PBL courses, reading groups, journal clubs,
Barriers to practicing EBM Time Information Resources Cost
Analysis of questions asked by family doctors regarding patient care Ely JW, et al. BMJ 1999;319:
Physicians’ Information Needs Ely JW, Osheroff JA, Chambliss ML, Ebell MH, Rosenbaum ME JAMIA 12 (2): MAR-APR 2005 Total Questions N=1,062 Pursued N= 585 (55%) Not Pursued N= 477 (45%) Answered, no difficulty N=238 (41%) Answered with difficulty N=180 (31%) Not Answered N=167 (28%) Why? Limited time, Suspect lack of information, Need better resources.
How 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 find Appraise- evaluate the evidence Apply- to patient care
Categories of Clinical Questions Diagnosis – Test A or B to differentiate between positive an negative Therapy – treatment A or B to improve a condition or avoid an adverse event Prognosis – future course of condition or disease Etiology/harm- effects of agents on function, morbidity, mortality
Systematic Reviews & Meta-analyses of RCTs Randomized Controlled Trials (RCTs) Systematic Reviews of Observational Studies Retrospective (case-control) Prospective (cohort) Case Series Case Reports Hierarchy of Evidence
Best Evidence for Clinical Questions Diagnosis and Therapy- randomized controlled trial –Eligible patients Prognosis and Etiology/Harm- observational studies outcome randomization treatment placebo Circumstances exposed not exposed outcome No outcome Eligible patients
Ask: 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
Ask: Build a focused query (PICO) P: terms describing the patient/problem I: terms describing the intervention C: list any alternative interventions O: terms defining the outcome of interest Do not need PICO for pre-filtered systematic reviews or meta-analyses
ASK: Focused query Patient / Problem Intervention Comparison Outcome congestive heart failure, elderly digoxin none, placebo primary: reduce need for hospitalization secondary: reduce mortality
The 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).
Acquire: Know the resources (ask a librarian!) Find the best available evidence Starting with PubMed
Acquire: Finding the best evidence in MedLine/PubMed: Therapy Questions PICO using MeSH terms where available Limit to meta-analyses OR randomized controlled trials OR clinical trials
Therapy Question: Acquire
The 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):
Therapy Question: Appraise Are the results valid? What do the results mean? (are they important?)
Appraise: validity questions for therapy articles Were patients randomized? Was randomization concealed? Were patients in experimental and control groups similar in terms of prognostic factors? Was follow up complete? AnswersAnswers: Article: This study methodology appears to be sound and the results are valid.
Appraise: Part 2- are the results important? OutcomePlaceboDigoxin Hospitalization due to CHF 35%27%
Appraise: Are the results important? Ways to quantify magnitude of treatment effect Relative Risk: Risk of the outcome in experimental group compared to the risk in the control group.. RR= outcome (exp) / outcome (con) = 27/35=.77 = 77% Relative Risk Reduction: The percent reduction of risk in the experimental group compared to the control group) RRR = outcome (con) – outcome (exp) / outcome (con) = 23%
Appraise…Are the results important Absolute Risk Reduction: The difference between outcome rates in experimental and control groups ARR= outcome (con) – outcome (exp) Example: 35% - 27% = 8% 100% 65% avoid the hospital either way 8% avoid the hospital by taking digoxin 27% are hospitalized either way
Appraise: 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/NNT NNT = 100% / ARR % = 100/8 = 13 patients need to be treated in order to avoid one hospitalization by using digoxin
RRR vs. ARR: Some papers report RRR only. Why is that a problem? % MortalityTreatmentControl RCT RCT RCT Calculate RRR, ARR and NNT for the following three RCTs
APPLY: Should we prescribe Digoxin for Pauline?
Diagnosis Questions Ask (PICO) Acquire (Systematic reviews, metaanalyses, RCTs) Appraise (Validity and Importance) –Validity questions differ for diagnosis –Data are different (sensitivity, specificity, likelihood ratios) Evidence-Based Medicine: How to practice and Teach EBM, Sackett DL, et al. NY: Churchill, 2000.
Diagnosis: Validity questions Key issues for Diagnostic Studies: –blinding –identified gold standard test –patient sample –each patient gets both tests
Diagnosis: 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.
Search Tip for Diagnosis Use the MeSH term “Sensitivity and Specificity” If that doesn’t work, use ONE of the terms in your search
Need a Break?
The Good News: We have Pre- Filtered Sources Cochrane Library/DARE ACP Journal Club NG Clearinghouse Trip Database (FREE!) Archie Cochrane
Demonstration: EBM resources Search “congestive heart failure” in Cochrane Library Search ACP journal Club Search TRIP database
Drug 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.
Drug Information Resources Clinical Pharmacology Micromedex
Exercises: work in groups, pick a question –Fred: Therapy –Amelia: Therapy –Myrtle: Diagnosis –Any questions you have had in your practice ASK ACQUIRE Appraise, if you have time. Validity questions are in your packet