7.2 Systematic Reviews and Meta-analyses

Question 1

What should healthcare be based on?

Answer 1

Best available evidence, should be based on rigorously conducted research

Question 2

Narrative reviews vs systematic reviews

Answer 2

Narrative
-Implicit assumptions
-Not reproducible
-Biased and subjective

Systematic
-explicit assumptions
-Transparent methodology
-Reproducible
-Unbiased and objective

Question 3

What is a systematic review?

Answer 3

Summary of medical literature conducted using explicit methods

E.g.
Clearly focused research question which explicitly states inclusion and exclusion criteria
-Types of study
-Types of participants
-Types of interventions
-Types of outcome measures

Question 4

Systematic review vs meta-analysis

Answer 4

Systematic
Overview of primary studies that used explicit and reproducible methods

Meta-analysis
Quantitative synthesis of the results of two or more primary studies that addressed the same hypothesis in the same way

Question 5

What are finding studies?

Answer 5

Thorough, systematic search of the published and grey literature

Grey literature-
Conference abstracts
PhD theses

Question 6

What is appraising?

Answer 6

Reviewing the results of the search to select relevant and valid studies

Question 7

What is the purpose of a meta-analysis?

Answer 7

-Facilitate synthesis or large number of study results
-Systematically collate results
-Reduce problems of interpretation due to variations in sampling
-Quantify effect sizes and their uncertainty as a pooled estimate

Question 8

What is the criteria of a meta-analysis?

Answer 8

-Compilation of complete set of studies
-Identification of common variable or. category definition
-Standardised data extraction
-Analysis incorporating for sources of variation

Question 9

How are pooled estimates calculated form odds ratio for all studies?

Answer 9

Odds ratios and their 95% CIs calculated in meta analysis

Combined to give a pooled estimate odds ratio

Studies are weighted according to their size and uncertainty of their odds ratio

Narrow CI- greater weight to result

Question 10

What does an OR > 1.00 indicate for these patients

Answer 10

Greater odds for survival amongst patients taking aspirin after MI

Only 1 RCt had a statistically significant result but it’s OR was less than the other RCTs with an OR > 1.00

Pooled estimate OR=1.11 leads to conclusion aspirin increases chance of survival after a MI