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How to Conduct a Meta-Analysis. Arindam Basu MD MPH About the Author Required Browsing. Objectives. Following the course, you will be able to : Define Meta-analysis Select Studies for a Meta-analysis Identify different types of Models Calculate Summary Effects

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how to conduct a meta analysis

How to Conduct a Meta-Analysis

Arindam Basu MD MPH

About the Author

Required Browsing

objectives
Objectives

Following the course, you will be able to:

  • Define Meta-analysis
  • Select Studies for a Meta-analysis
  • Identify different types of Models
  • Calculate Summary Effects
  • Interpret Results of a Meta-analysis
what is meta analysis
What is Meta-analysis?
  • Synthesis of previous studies
  • Providing a Summary estimate
  • Steps
    • Identify studies
    • Define Eligibility Criteria
    • Abstract Data
    • Do Statistical Analysis
identify studies overview
Identify Studies: Overview
  • Steps:
    • Search Your Personal Files First
    • Search Electronic Databases
    • Review Reference Lists of Articles
    • Contact Experts and Researchers
    • Retrieve New Articles
  • Evaluate Quality of the Studies
  • Set Up Eligibility Criteria
searching electronic databases
Searching Electronic Databases
  • First, Define a Search Strategy
  • Limitations of Databases
    • incomplete and imperfect queries
    • language problems
    • problems with fugitive literature
  • Publication Bias is important
    • What is publication bias
    • How to deal with publication bias
evaluating study quality
Evaluating Study Quality
  • Define Study Quality Criteria Early
  • Set Up A Good Scoring System
  • Develop A Form for Assessment
  • Calculate Quality for each Study
  • Use this for Sensitivity Analysis
    • stratify studies according to quality
defining eligibility of studies
Defining Eligibility of Studies

Select Eligible Studies Based On:

  • Study Designs
  • Years of Publication
  • Language
  • Choice among multiple articles
  • Sample-size or follow-up issues
  • Similarity of Exposure and/or Rx
  • Completeness of information
abstract data review
Abstract Data - Review!

Steps:

  • Identify Relevant Articles
  • Sort out Eligible Articles
  • Set up a Form for Abstraction
  • Enter the Eligible Studies
  • Use this as your database

Statistical Analysis is next...

statistical analysis overview
Statistical Analysis - Overview
  • Select An Estimate of Effect
  • Choose An Effects Measure
  • Select An Effects Model
  • For Each Model:
    • Calculate Summary Effect Size
    • Calculate Confidence Intervals
    • Calculate Q-statistic for Homogeneity
  • Perform Sensitivity Analysis
selecting estimate of effect
Selecting Estimate of Effect
  • Choose Only One Estimate
  • For RCTS, choose the one with
    • Once randomized always randomized
  • For nonrandomized trials, choose:
    • estimate adjusted only for age
    • that, and for a known confounder
    • the “most adjusted” estimate
    • estimate presented in the abstract
choosing an effect measure
Choosing An Effect Measure
  • RCTs or Cohort Studies
    • Rate Difference between Treatment and Control Groups
    • Ratio of Disease Rates
  • Case Control Studies
    • Odds’ Ratio
    • Rate Ratio
selecting an effects model
Selecting An Effects Model
  • Available Types:
    • Fixed Effects Model
    • Random Effects Model
  • Difference Between the Two
  • Special Cases:
    • When Outcomes are not binary
  • Methods to be Used for them
fixed effects model
Fixed Effects Model
  • Methods:
    • Mantel Haenszel Method
    • Peto’s Method
    • General Variance Based Methods
      • For Rate Difference
      • For Rate Ratios
      • When only RR and 95 CI given
  • Tests of Homogeneity
    • Calculation of Q Statistic
mantel haenszel method
Mantel Haenszel Method
  • Download Spreasheet Calculator
  • Strength of Mantel Haenszel
    • Very powerful
    • Widely Used
  • Limitation
    • Cannot Control For Confounding!
peto s method
Peto’s Method
  • Similar to Mantel Haenszel
  • Download Calculator
  • Simpler Computation
  • No Control for Confounding
  • Good for RCTs
  • Requires 2 X 2 Table
variance based methods
Variance-Based Methods
  • Download Calculators For:
    • Rate Difference
    • For only Relative Risk and 95% CI
  • Strengths and Limitations
    • Good For Rate Differences
    • Computationally Intensive
tests of homogeneity
Tests of Homogeneity
  • Establish Null Hypothesis that Effect Sizes Are Equal in All of the Studies [FAIL TO REJECT NULL]
  • Tested By Using Q-statistic
  • Q-statistic is distributed as chi-square distribution with degree of freedom = n-1 where n = number of studies
random effects model
Random Effects Model
  • Download The Calculator!
  • Strengths and Limitations:
    • Can Generalize the Conclusions
    • Computationally Intensive
continuous outcomes
Continuous Outcomes
  • Measurement Scale: Continuous
  • Outcome Measured in Same Scale
    • Download Spreadsheet Calculator!
  • Essentially Extension of ANOVA
  • Useful For Integrating Social Science Research Data
sensitivity and publication bias
Sensitivity and Publication Bias
  • Conduct Sensitivity Analysis
    • Stratify studies by their quality rating
    • Compare Fixed and Random Effects
  • Deal With Publication Bias
    • Construct A Funnel Plot
conclusion
Conclusion
  • Presentation of Meta-analysis or Literature Synthesis
  • Download The Graph Maker
  • More Resources...
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