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15 Cards in this Set
- Front
- Back
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Null Hypothesis (H0)
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No difference between two populations
Between exposure and outcome Between two treatments for improvement |
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Alternative hypothesis (H1)
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There is some difference
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SEE slide
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6 and 7
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Statistical Power
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Likelihood a study correctly disproves the null hypothesis
In lay terms, likelihood of finding a difference between two groups |
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Statistical Power calculations
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1 - Beta
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Statistical Power Depends on:
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The effect size (i.e. the amount of difference investigator desires to detect between groups)
The level of significance desired (p value) The sample size |
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Calculate and interpret NNT and NNH
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NNT = 1/ARR
NNH = 1/ARI |
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5 Steps in the EBM Process
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Formulating a searchable question
Searching the literature efficiently Appraising the literature critically Internal validity, statistical significance, clinical significance Applying the result to clinical practice or patient (external validity or generalizability) Evaluating the outcomes of the applied evidence in your practice or patient |
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5 Steps in the EBM Process 1) Formulating a searchable question PICO
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Patient
-70 year old Caucasian male Intervention -Vitamin D supplementation Comparison -No supplementation Outcome -Fewer complications from falls such as hip and nonvertebral fractures |
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Inclusion Criteria appropriate
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Only double-blind randomized controlled trials
Participants’ mean age > 60 years Oral Vitamin D supplementation Compared to Calcium alone or placebo Follow-up of at least 1 yr Outcomes of hip or nonvertebral fractures |
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An evidence database must be:
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Fast
Able to answer most questions To make EBM feasible in routine practice |
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Barriers to accessing electronic EB
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Time
Resources (hardware, software) Setting In the exam room Walk-and-talk Format Handhelds / smartphones Electronic format not always ideal Paper-based resources |
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Strength of Recommendation Grades
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A = Good and consistent patient-oriented evidence
B = Limited and/or inconsistent evidence C = Consensus, opinion, usual practice, disease-oriented evidence, case-series |
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Systematic review
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identify, appraise, select and synthesize all high quality research evidence
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Meta Analysis
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statistically combines the results of many different studies
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