Systematic Review and Meta Analysis

Question 1

What is a systematic review

Answer 1

Review of all the evidence available concerning a clearly formulated question to identify, select, critically appraise, collect data and analyse data

Question 2

What is considered in a systematic review

Answer 2

PIOS
Population
Intervention/comparison
Outcomes
Study design

Question 3

Why are systematic reviews carried out

Answer 3

Large quantity of data
Individual studies cannot conclusively answer a research question
Many studies give contradictory results

Question 4

Define meta analysis

Answer 4

use of statistical techniques to integrate the results of included studies, combining the published estimated of effect from each study to generate a pooled risk estimate

Question 5

What kind of unit is meta analysis

Answer 5

primary units of analysis

Question 6

What are the advantages of meta analysis

Answer 6

Generate a pooled overall risk estimate
Produce a more reliable and precise estimate of effect
Explore differences (heterogeneity) between published studies
Identify whether publication bias is occurring
Provide evidence-base for clinical decisions.

Question 7

What are the limitations of meta analysis

Answer 7

Publication bias
Inconsistency of results (heterogeneity)
Low study quality

Question 8

Describe publication bias in meta analysis

Answer 8

Only a subset of the relevant data is available
Null of non-significant findings (especially in small studies) are less likely to be reported/published than statistically significant findings
Published studies may not be representative of all valid studies