vanderbilt sports medicine selecting literature an evidence-based medicine approach kurt p....
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Vanderbilt Sports Medicine
SELECTING LITERATUREAn Evidence-Based Medicine
Approach
SELECTING LITERATUREAn Evidence-Based Medicine
ApproachKurt P. Spindler, MD
Professor & Vice Chair, OrthopaedicsDirector, Vanderbilt Sports Medicine & Ortho PCC
Head Team Physician, Vanderbilt University
B+JD Young Investigators InitiativeMay 13-15, 2005
Why EBM Select Literature?
1. Identify clinically relevant problem!2. Limit selection BIAS in peer- review
paper3. Learn hierarchy clinical studies4. Develop hypothesis from best study
designs5. Caveat: still need to play to study
sections bias for innovation and “clinical importance”
Is There Evidence in Literature Supporting EBM Approach for
ORTHOPAEDICS?1. JBJS-A, Jan 2003 Editorial (Heckman)
• Introducing levels of evidence• Five levels• Four study types
2. AJSM, 2002 Abstract Format (Reider)• Background• Hypothesis• STUDY DESIGN: list• Methods / Results / Conclusion• Clinical relevance
GOAL: Reach for Peaks!EBM approach review clinical literature
Concepts apply basic science
Application template
Basics
Title
Author
Reference
HYPOTHESIS– PRIMARY– SECONDARY
Type of Study
Treatment
Diagnosis
Screening
Prognosis
Causation
CLINICAL PRACTICE
In vitro• cell/matrix• gene biomechanic
THOUSANDS
In vivo• relevant animal models• biology • healing• biomechanic• safety
TENS OF THOUSANDS
Controlled Clinical Trials• outcomes• complications• risk/benefit• cost/benefit
HUNDREDS OF THOUSANDS
StudyDesign:
Cost:
ExtremeExtremeCAUTIONCAUTION
MAYBEMAYBE
YES: EBMYES: EBM
Clinical QUESTIONDetermines Study Design
Research ExamplePreferred
Study Design
Therapy Autograft choice RCT
Diagnosis Labral tearCross-sectional survey
ScreeningRole flexibility as injury risk
Cross-sectional survey
PrognosisPredictors OA after ACLR
Longitudinal cohort study
Risk FactorRisk OA Div I Athlete
Cohort or case control
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
Study Type with Preferred Design
Sports Medicine Question
Ho: Anterior knee pain after ACL reconstruction is dependent on
autograft choice between Ham vs PTWhat do you believe?Approach to literature review:– Select articles that support your bias?–What is research topic?– Treatment choice– Focus review -- RCTs
Traditional Hierarchy ofClinical Treatment Studies
1. RCT (randomized controlled trials) = only computer or random # table acceptable
2. Cohort: two or more groups selected basis differences exposure to “agent” and f/u
3. Case control: pts particular disease/condition identified + “matched” control
4. Cross-sectional: data collected single timepoint5. Case reports/series: medical hxs one or more
patients with condition/tx reported on
Why do Treatment Studies Need Control Group?
1. Basics Scientific Method!
2. If no control group: tx is same, better, or worse than what?
3. Quality of “control” group one measure of validity of results
4. Unfortunately majority orthopaedic literature lack control group -- case series
Anterior Knee Pain S/P ACL Recon
Ho: Autograft choice Ham vs PTEBM Review: Systematic review nine RCTsRef: Spindler AJSM 2004Answer: NO DIFFERENCE 8/9 studies!Caveat:
a. Kneeling pain > PT 4/4 studies!b. Bynum PT ACL Recon PF pain
Preop = 40%, Postop = 20%, p < 0.05
Basic Science Grant
1. FOCUS LITERATURE EBM2. HYPOTHESIS: focus EBM key
clinical problem3. 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
How to Identify Bias Study BIAS Example
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?
Definition of Bias1. SELECTION or SUSCEPTIBILITY = difference in
comparison groups secondary to incomplete randomization
2. PERFORMANCE = differences in care provided apart from intervention being evaluated
3. EXCLUSION or TRANSFER = differences in withdrawal from trial
4. DETECTION = different evaluation for outcomes best independent examiner or blinding examiner or validated outcome questionnaire self-administered
Sports Medicine Examples Bias
1. 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
2. PERFORMANCE:• Report outcome of meniscal allograft or autologous
chondrocytes fail control concomitant ACL recon or HTO!
3. EXCLUSION OR TRANSFER:• Report conclusions based <70% f/u outcome variable
Statistical and Clinical Significance Outcomes
Absolute If ns power = ( ) ClinicallyAbsolute If ns power = ( ) Clinically
Outcome/Result Difference P for ( ) diff significantOutcome/Result Difference P for ( ) diff significant
a.a.
b.b.
c.c.
d.d.
Examples Statistical Significance vs Clinical Significance
1. Primary Ho and each AIM determine sample size by choosing a clinically meaningful difference in a single result or outcome measure chosen
2. 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)
3. Thus clinical significance is based on both individual and “consensus” scientific community
4. Power or sample size set at 80% avoid Type II () error
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.
Pearls
1. Develop ideas methods, results, statistics from best EBM in literature review based on realities previously discussed.
2. Retrospective review “your” cases!• Establish sample size• Timelines to complete• Generate methods
3. Consult statistician BEFORE begin study!
Summary1. EBM review literature2. Generate hypothesis (Ho)3. Construct preliminary AIMS4. Review literature modify Ho
and AIMS5. Develop TEAM6. CONSULT STATISTICIAN7. Clinical retrospective
reviews clinical pts, variation, outcomes
ReferencesWright 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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