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SELECTING LITERATURE An Evidence-Based Medicine Approach

B+JD Young Investigators Initiative May 13-15, 2005. SELECTING LITERATURE An Evidence-Based Medicine Approach. Kurt P. Spindler, MD Professor & Vice Chair, Orthopaedics Director, Vanderbilt Sports Medicine & Ortho PCC Head Team Physician, Vanderbilt University. Why EBM Select Literature?.

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SELECTING LITERATURE An Evidence-Based Medicine Approach

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  1. B+JD Young Investigators Initiative May 13-15, 2005 SELECTING LITERATUREAn Evidence-Based Medicine Approach Kurt P. Spindler, MD Professor & Vice Chair, Orthopaedics Director, Vanderbilt Sports Medicine & Ortho PCC Head Team Physician, Vanderbilt University

  2. Why EBM Select Literature? • Identify clinically relevant problem! • Limit selection BIAS in peer- review paper • Learn hierarchy clinical studies • Develop hypothesis from best study designs • Caveat: still need to play to study sections bias for innovation and “clinical importance”

  3. Is There Evidence in Literature Supporting EBM Approach for ORTHOPAEDICS? • JBJS-A, Jan 2003 Editorial (Heckman) • Introducing levels of evidence • Five levels • Four study types • AJSM, 2002 Abstract Format (Reider) • Background • Hypothesis • STUDY DESIGN: list • Methods / Results / Conclusion • Clinical relevance

  4. GOAL: Reach for Peaks! • EBM approach review clinical literature • Concepts apply basic science • Application template

  5. Title Author Reference HYPOTHESIS PRIMARY SECONDARY Basics

  6. Type of Study • Treatment • Diagnosis • Screening • Prognosis • Causation

  7. CLINICAL PRACTICE Extreme CAUTION YES: EBM MAYBE • Controlled Clinical Trials • outcomes • complications • risk/benefit • cost/benefit • HUNDREDS OF THOUSANDS • In vitro • cell/matrix • gene • biomechanic • THOUSANDS • In vivo • relevant animal • models • biology • healing • biomechanic • safety • TENS OF THOUSANDS Study Design: Cost:

  8. Clinical QUESTIONDetermines Study Design

  9. Study Type with Preferred Design 1° HYPOTHESIS OR PREFERRED TOPIC RESEARCH [EXAMPLES] RESEARCH DESIGN TREATMENT [DRUG, PREVEN- RCT TION, SURG] Diagnosis [dx test] Cross-sect survey Screening [value of test] Cross-sect survey PROGNOSIS [DISEASE, INJURY, LONGITUDINAL CONDITION] COHORT Causation [exposure to . . . ] Cohort or case-control

  10. Sports Medicine Question • Ho: Anterior knee pain after ACL reconstruction is dependent on autograft choice between Ham vs PT • What do you believe? • Approach to literature review: • Select articles that support your bias? • What is research topic? • Treatment choice • Focus review -- RCTs

  11. Traditional Hierarchy ofClinical Treatment Studies • RCT (randomized controlled trials) = only computer or random # table acceptable • Cohort: two or more groups selected basis differences exposure to “agent” and f/u • Case control: pts particular disease/condition identified + “matched” control • Cross-sectional: data collected single timepoint • Case reports/series: medical hxs one or more patients with condition/tx reported on

  12. Why do Treatment Studies Need Control Group? • Basics Scientific Method! • If no control group: tx is same, better, or worse than what? • Quality of “control” group one measure of validity of results • Unfortunately majority orthopaedic literature lack control group -- case series

  13. Anterior Knee Pain S/P ACL Recon Ho: Autograft choice Ham vs PT EBM Review: Systematic review nine RCTs Ref: Spindler AJSM 2004 Answer: NO DIFFERENCE 8/9 studies! Caveat: • Kneeling pain > PT 4/4 studies! • Bynum PT ACL Recon  PF pain Preop = 40%, Postop = 20%, p < 0.05

  14. Basic Science Grant • FOCUS LITERATURE EBM • HYPOTHESIS: focus EBM key clinical problem • BEST STUDY DESIGN TOPIC • Clinical relevance—systematic reviews • Background—related topics • Prelim data—review similar studies • Design—metrics, techniques, alternatives • Stats—method, sample size or power

  15. How to Identify Bias Study BIASExample Allocation groups Selection Fail randomize Intervention Performance Fail control confounding variables Follow-up Exclusion Not uniform or (or Transfer) inadequate (<70%) Outcomes Detection Dissimilar evaluation independent examiner? Validated question- naire?

  16. Definition of Bias • SELECTION or SUSCEPTIBILITY = difference in comparison groups secondary to incomplete randomization • PERFORMANCE = differences in care provided apart from intervention being evaluated • EXCLUSIONorTRANSFER = differences in withdrawal from trial • DETECTION = different evaluation for outcomes best independent examiner or blinding examiner or validated outcome questionnaire self-administered

  17. Sports Medicine Examples Bias • SELECTION: • ACL tr pt self-select OR vs Nonop tx = evaluate OA • Soccer teams self-select ACL inj prevention training, then report difference incidence ACL tr • PERFORMANCE: • Report outcome of meniscal allograft or autologous chondrocytes fail control concomitant ACL recon or HTO! • EXCLUSION OR TRANSFER: • Report conclusions based <70% f/u outcome variable

  18. Statistical and Clinical Significance Outcomes Absolute If ns power = ( ) Clinically Outcome/Result Difference P for ( ) diff significant a. b. c. d.

  19. Examples Statistical Significance vs Clinical Significance • Primary Ho and each AIM determine sample size by choosing a clinically meaningful difference in a single result or outcome measure chosen • Instrumented Laxity (KT 1000) ACL Recon Graft Choice • Literature studies powered detect 1 mm side to side difference (n ≈ 70) • How many surgeons would change practice if results 1 mm (few) vs 2 mm (some) vs 3 mm (many) • Thus clinical significance is based on both individual and “consensus” scientific community • Power or sample size set at 80% avoid Type II () error

  20. Ideal vs Reality in Study Section • NIAMS has no study section for clinical research/outcomes. • If your systematic review does not support perceived bias think twice. Recommend refocus support bias. • Clinical significance vs statistical significance not well understood by basic science study sections. Plethora funded NIAMS studies without clinical significance but positive statistical results. • Seek expert funded opinion on your grant.

  21. Pearls • Develop ideas methods, results, statistics from best EBM in literature review based on realities previously discussed. • Retrospective review “your” cases! • Establish sample size • Timelines to complete • Generate methods • Consult statistician BEFORE begin study!

  22. Summary • EBM review literature • Generate hypothesis (Ho) • Construct preliminary AIMS • Review literature modify Ho and AIMS • Develop TEAM • CONSULT STATISTICIAN • Clinical retrospective reviews clinical pts, variation, outcomes

  23. Thank You

  24. References Wright JG: JBJS-Am 2000 Hurwitz SR: JBJS-Am 2000 McLeod RS: Surgery 1996 Greenhalgh T: How to Read a Paper. Br Med J 2001 Lang TA and Secic M: How to Report Statistics in Medicine. ACP 1997 Spindler K, Johnson R, Reider B: ICL AOSSM 2002

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