Systematic reviews

Question 1

Systematic review

Answer 1

aims to answer a defined research question by collecting and summarising empirical evidence that fits prespecified eligibility criteria

Question 2

What do systematic reviews provide

Answer 2

More generalisable conclusions

Comprehensive summary of knowledge

Question 3

Advantages of systematic review

Answer 3

Transparent inclusion of studies
MA increases power of study
May identify lack of adequate evidence

Question 4

Stage 1 of systematic review

Answer 4

Planning the review

Define research question

Question 5

Stage 2 of a systematic review

Answer 5

Identification of research (search criteria and thorough search)
Selection of studies (with inclusion and exclusion criteria)
Study quality assessment (establish whether bias exists)

Question 6

Stage 3 of a systematic review

Answer 6

Reporting and dissemination
Details and effect estimate abstracted
Estimate overall effect by combining data
if meta-analysis is appropriate

Question 7

Meta analysis

Answer 7

Integrates results of studies matching eligibility criteria

Generates a pooled risk estimate

Question 8

Advantages of a meta analysis

Answer 8

More subjects included= more reliable

Differences (heterogeneity) between studies can be identified

Question 9

If studies are too heterogeneous

Answer 9

May be inappropriate to pool results

Question 10

Forest plot

Answer 10

graph of results from each study included in a systematic review, together with the combined meta- analysis result

Question 11

What is each study represented by on a forest plot?

Answer 11

Box and line

Question 12

What does the size of the box in a forest plot signify?

Answer 12

The weight of the study

Question 13

What does the horizontal line in a forest plot signify?

Answer 13

95% confidence interval

Question 14

What does the diamond in a forest plot signify?

Answer 14

The overall estimate of the meta analysis

“pooled point estimate”

Question 15

What does the centre of the diamond and dashed line in a forest plot signify?

Answer 15

Summary effect estimate

Question 16

What does the width of the diamond in a forest plot signify?

Answer 16

The confidence interval around this estimate

Question 17

Publication bias

Answer 17

greater likelihood of research with statistically significant results to be published

Question 18

What can show publication bias?

Answer 18

Funnel plots

Question 19

What do funnel plots indicate?

Answer 19

whether there is a link between study size (or precision) and the effect estimate

Question 20

Heterogeneity

Answer 20

Studies trying to answer the same question may still differ with respect to the exact population, interventions/exposure, outcomes & designs used

Question 21

Even when factors are homogeneous

Answer 21

heterogeneity may still exist

because of clinical differences, methodological differences or unknown study characteristics.

Question 22

How to explore heterogeneity

Answer 22

Galbraith (radial) plots

Question 23

Limitations of systematic reviews

Answer 23

If too few studies matching eligibility criteria, a systematic review might not add much.
Inadequate methodological quality of studies can compromise findings of reviews
Publication bias can distort findings