1 / 21

How to Conduct a Meta-Analysis

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

renee
Télécharger la présentation

How to Conduct a Meta-Analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. How to Conduct a Meta-Analysis Arindam Basu MD MPH About the Author Required Browsing

  2. 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

  3. What is Meta-analysis? • Synthesis of previous studies • Providing a Summary estimate • Steps • Identify studies • Define Eligibility Criteria • Abstract Data • Do Statistical Analysis

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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...

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. Mantel Haenszel Method • Download Spreasheet Calculator • Strength of Mantel Haenszel • Very powerful • Widely Used • Limitation • Cannot Control For Confounding!

  15. Peto’s Method • Similar to Mantel Haenszel • Download Calculator • Simpler Computation • No Control for Confounding • Good for RCTs • Requires 2 X 2 Table

  16. Variance-Based Methods • Download Calculators For: • Rate Difference • For only Relative Risk and 95% CI • Strengths and Limitations • Good For Rate Differences • Computationally Intensive

  17. 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

  18. Random Effects Model • Download The Calculator! • Strengths and Limitations: • Can Generalize the Conclusions • Computationally Intensive

  19. Continuous Outcomes • Measurement Scale: Continuous • Outcome Measured in Same Scale • Download Spreadsheet Calculator! • Essentially Extension of ANOVA • Useful For Integrating Social Science Research Data

  20. 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

  21. Conclusion • Presentation of Meta-analysis or Literature Synthesis • Download The Graph Maker • More Resources...

More Related