The document discusses the selection criteria and data extraction process for conducting systematic reviews and meta-analyses, emphasizing the need for homogeneity in literature and a targeted approach to screening studies. It outlines the creation of a data extraction sheet, requiring collaboration between two authors, and highlights the key information to be extracted based on the study question. Additionally, it addresses assumptions made during analysis and the importance of critical appraisal to assess the quality and bias of individual studies.

1. Basics of Systematic Review and
Meta-analysis
Part 2: Selection criteria and data extraction
Dr. S. A. Rizwan, M.D.,
Department of Community Medicine,
Velammal Medical College Hospital and Research Institute,
Madurai.

2. Selection criteria
• Necessary to make sure that the literature
used will be homogenous to the extent
possible
• To screen out a large body of irrelevant studies
• No one uniform criteria, depends on the study
question
• How to handle duplicate data or study

3. Example of selection criteria

4. Data extraction sheet
• Two authors needed
• First develop a pre-coded extraction sheet
together
• All relevant information from the study should
be extracted
• If certain info is not available in the full text or
abstract, contact the authors atleast twice

5. What info to extract
• Will depend on study question
• Basics
– study author, year of publication
– year of study
– sample size
– study design
– study population details
– outcome measure definition, exposure measure
definition
– effect size
– other comments

6. Example of data extraction sheet

7. Assumptions
• We cannot get data in the same manner in all
studies
• Therefore, we make certain assumptions to
carry the analysis forward
• Eg., Risk due to different forms of smokeless
tobacco use was considered to be equal

8. Effect size
• The main measure that we are going meta-
analyse
• Example
– Prevalence
– Odds ratio, relative risk
– Intervention effect
– Diagnostic test measures
– Others

9. Appraisal of individual study
• Use appropriate critical appraisal checklists
such as CASP, Cochrane risk of bias
assessment and others appropriate tools
• Classify studies into high or low quality, or
high or low risk of bias
• Will be used for sensitivity analysis

10. Example of critical appraisal

11. Example of critical appraisal

12. THANK YOU