An introduction to Evidence-based medicine Steve Allen, MD Scott & White Clinic Temple, TX

Educational objectives  Define EBM  Learn the steps to implement EBM  Apply your new knowledge!  Identify barriers to EBM implementation  Determine strategies to overcome those barriers

Evidence based medicine  EBM is the integration of current best research evidence with clinical expertise and patient values  EBM shifts authoritarianism to scientific skepticism  EBM is an active process Life-long Problem based learning

History of EBM  Valid data: Randomized clinical trials rare into 1960s and beyond  “EBM” coined in 1992 – Guyatt et McMaster Univ “EBM” articles, PubMed n = 6

The EBM paradigm shift  Understanding of pathophysiologic principles  Clinical experience  Common sense  Reliance on expert opinion  Knowledge of pathophysiology is necessary but insufficient  Systematic approach increases certainty of diagnostic validity & management strategies  Formal rules of evidence

Strength of Recommendations USPSTF 2004  A. Strongly recommends that clinicians provide [the service] to eligible patients: good evidence that [the service] improves important health outcomes; benefits substantially outweigh harms.  B. Recommends that clinicians provide [this service] to eligible patients: at least fair evidence.

Strength of Recommendations USPSTF 2004  C. No recommendation for or against routine provision of [the service]; the balance of benefits and harms is too close to justify a general recommendation.  D. Recommends against routinely providing [the service] to asymptomatic patients.  E. Evidence is insufficient to recommend for or against routinely providing [the service].

Quality of Evidence USPSTF 2004  Good: Consistent results from well-designed, well- conducted studies in representative populations that directly assess effects on health outcomes.  Fair: Evidence sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality, or consistency of the individual studies, generalizability to routine practice, or indirect nature of the evidence on health outcomes.  Poor: Evidence insufficient to assess the effects on health outcomes.

The need for EBM  Daily need for valid information 5x/inpatients 2x/3 outpatients  Inadequacy of traditional sources – out of date or wrong  Disparity between skills and knowledge over time  Time restrictions seconds per patient max 30 min/wk

Developments which facilitate the practice of EBM  Strategies for appraising evidence (ex: meta-analysis)  Systematic reviews & concise summaries (ex: Cochrane Collaboration; practice guidelines)  Information systems to deliver data efficiently

Implementation of EBM “EBM levels the intellectual playing field” * Everyone’s opinion counts equally – regardless of rank Opinions valued only to the extent that they are supported by scientific evidence When a question arises, it should be addressed through formal review – rather than by faculty edict * Grimes DA. OG 1995;86:451

EBM: the process 1.Convert information need into focused question 2.Find the best evidence to answer the question 3.Critically appraise the evidence for its validity and clinical usefulness 4.Integrate the critical appraisal with clinical expertise and the patient’s unique circumstances 5.Evaluate performance – seek ways to improve next time

Usefulness of EBM Usefulness of a source Relevance x Validity Work =

POEM trumps DOE “The influence of obesity and diabetes on the prevalence of macrosomia” Ehrenberg et al AJOG 2004;191;964 “The influence of obesity and diabetes on the risk of cesarean delivery” Ehrenberg et al AJOG 1004;191:969

EBM: individualization Not all questions require the maximum work “just in time” sources for common questions Low work; rely on someone else to do the critical analysis ex: practice guidelines “just in case” sources for complex and atypical cases High work; you must do the critical analysis yourself

EBM: the process 1.Convert information need into focused question 2.Find the best evidence to answer the question 3.Critically appraise the evidence for its validity and clinical usefulness 4.Integrate the critical appraisal with clinical expertise and the patient’s unique circumstances 5.Evaluate performance – seek ways to improve next time

Clinical case #1 A 29 yo obese white P1001 with HHT (hereditary hemorrhagic telangiectasia syndrome) and Type 2 diabetes presents for prenatal care at 14 weeks gestational age. List 3 pertinent questions to help you provide optimal medical care to this patient. 1) 2) 3)

Well-formulated clinical questions Background questions  Ask for general knowledge about a disorder  2 essential components Question root (who, what, where … ) & a verb The disorder Foreground questions  Ask for specific knowledge about pt management  3-4 essential components Patient and/or problem Intervention Comparison intervention Clinical outcomes

Types of questions Background Foreground

Topics for well-formulated clinical questions  Clinical findings  Etiology  Clinical manifestations  Differential diagnosis  Diagnostic tests  Prognosis  Therapy  Prevention  Experience & meaning  Self-improvement

Clinical case #2 A 29 yo obese white P1001 with Type 2 diabetes presents for prenatal care at 14 weeks gestational age. For the last 2 years she has taken glyburide to control her DM. List 3 pertinent questions to help you provide optimal medical care to this patient. 1) 2) 3)

Types of questions Background Foreground

Clinical case #2 Regarding your most important question  Question:  Your best answer (without searching):  Initial evidence resource:

EBM: the process 1.Convert information need into focused question 2.Find the best evidence to answer the question 3.Critically appraise the evidence for its validity and clinical usefulness 4.Integrate the critical appraisal with clinical expertise and the patient’s unique circumstances 5.Evaluate performance – seek ways to improve next time

EBM on EBM Does providing evidence based care improve outcomes for patients? The data are not yet available! … (But that is not an excuse to ignore EBM)

Clinical case #2 A 29 yo obese white P1001 with Type 2 diabetes (Rx: glyburide) presents for prenatal care at 14 weeks gestational age. Pertinent questions: 1) Glyburide’s mechanism of action? 2) Glyburide’s safety for pregnancy? 3) Glyburide’s efficacy during pregnancy?

Clinical case #2 most important questions  Question: Glyburide’s mechanism of action?  Your best answer (without searching): Promotes insulin secretion  Initial evidence resource: Micromedex

Clinical case #2 most important questions  Question: Glyburide’s mechanism of action?  Your best answer (without searching): Promotes insulin secretion  Initial evidence resource: Micromedex  Your final answer:

Clinical case #2 most important questions  Question: Glyburide’s safety for pregnancy?  Your best answer (without searching): No great risk for teratogenesis  Initial evidence resource: PubMed search

Clinical case #2 most important questions  Question: Glyburide’s safety for pregnancy?  Your best answer (without searching): No great risk for teratogenesis  Initial evidence resource: PubMed search  Your final answer:

Clinical case #2 most important questions  Question: Glyburide’s efficacy during pregnancy?  Your best answer (without searching): Fairly effective BS control  Initial evidence resource: PubMed Search

Clinical case #2 most important questions  Question: Glyburide’s efficacy during pregnancy?  Your best answer (without searching): Fairly effective BS control  Initial evidence resource: PubMed Search  Your final answer:

Barriers to EBM  Time  Critical evaluation skills  Institutional/academic chauvinism  Reluctance to question authority  Medical inertia  Numerators of one  Technological disability  Lack of high quality evidence for many clinical questions

The End