Lecture How to read a Systematic Review: The FAST tool

This lecture includes these contents: How to read a systematic review, the fast tool, a systematic review, selective criticism of evidence, meta analysis plot, pros and cons of systematic reviews,... Invite you to consult this lecture.

How to read a Systematic Review:

The FAST tool

Are RCTs always needed for

What do you do?

• For an acutely ill patient, you do a search 

• You find several studies: some show 

significant results but many others don’t

Of these 17 studies: of streptokinase for MI

How large should the study be?

What sample size is needed?

For disease X the usual mortality rate is 0%What sample size is needed to detect a 

Sample Size: Café Rule 1

The 50:50 Rule (proportions)

50 events are needed in the control group:

(For an 80% chance of finding a 50% reduction)

Glasziou P, Doll H Was the study big enough? Two cafe rules Evid Based Med 2006;11(3):69-70.

What sample size is needed?

• There is usually a 12% mortality rate

 You think your treatment will lower mortality 

by 50%

• What sample size is needed?

What sample size is needed?

Systematic Review or meta-analysis?

• A Systematic Review is a review of a clearly 

formulated question that uses systematic and  explicit methods to identify, select and critically  appraise relevant research, and to collect and  analyse data from the studies that are included 

in the review. 

• Statistical methods (meta­analysis) may or may 

not be used to analyze and summarize the 

results of the included studies.

Is the review any good? FAST appraisal

Why do I need to check the review?

What it the review question (PICO)?

Do pedometers increase activity and improve health?

FIND: Did they find all Studies?

Is finding all published studies enough?

Registered vs Published Studies

Ovarian Cancer chemotherapy: single v combined

Registered vs Published Studies

Ovarian Cancer chemotherapy: single v combined

Which are biased? Which OK?

Publication Bias: Solution

APPRAISE & select studies

Did they select only the 

good quality studies?

APPRAISE SYNTHESISE TRANSFERABLE FIND

Capital punishment: beliefs and contradictory studies

Selective Criticism of Evidence

Biased appraisal increases polarization

Lord et al, J Pers Soc Psy, 1979, p2098 APPRAISE SYNTHESISE TRANSFERABLE FIND

Selective Criticism of Evidence

28 reviewers assessed one “study”

results randomly positive or negative

(Cog Ther Res, 1977, p161-75)

APPRAISE SYNTHESISE TRANSFERABLE FIND

Assessment: How can you avoid biased

Synthesis: pooling the results

APPRAISE SYNTHESISE TRANSFERABLE FIND

Meta-analysis (Forest) plot

APPRAISE SYNTHESISE TRANSFERABLE FIND

Transferable? Use in my patients

Meta-analysis (Forest) plot

Are these trials different?

APPRAISE SYNTHESISE TRANSFERABLE

FIND

Pros and cons of systematic reviews

Is the review any good? FAST appraisal

Combined results

Using review results:

what do I do with my patient?

APPRAISE SYNTHESISE TRANSFERABLE

FIND

Summary: systematic reviews

(i) statistically significant * and

(ii) Clinically significant +?

• Which studies (presented as Odds Ratio):

 Are not statistically significant?

 Have < 50 patients in the control arm?

Sample Size: Cafe Rule 2 - continuous

the 17/(SD squared) Rule

For continuous outcomes, number per arm is

17 / (“worthwhile difference” measured in SDs)

In a small randomized double-blind trial of a new treatment for acute myocardial infarction, the mortality in the treated group was half that in the control group, but the difference was not significant We can conclude that:

The best evidence for different types

Has the systematic reviewer done a good job?

Are the studies equivalent?

Is bed rest ever helpful?

A systematic review of trials*

Serpell M, BMJ 1998;316:1709–10

years preceding