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How to read a Systematic Review: The FAST tool. F ind A ppraise S ynthesise T ransferability. Paul Glasziou Centre for Evidence Based Medicine University of Oxford www.cebm.net. Are RCTs always needed for treatment questions?. Some immediate & dramatic effects don’t need RCTs*

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how to read a systematic review the fast tool

How to read a Systematic Review: The FAST tool

Find

Appraise

Synthesise

Transferability

Paul Glasziou

Centre for Evidence Based Medicine

University of Oxford

www.cebm.net

are rcts always needed for treatment questions
Are RCTs always needed for treatment questions?
  • Some immediate & dramatic effects don’t need RCTs*
  • Example:
  • Child with nasal foreign body
    • Dislodged with Parent Kiss method
    • Case series of success 15/19
      • Botma J Laryngol Otol 2000

* Glasziou, Chalmers, Rawlins, McCulloch BMJ 2007

what do you do
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
slide4

Forest Plot/Blobbogram: of these 17 studies

  • Which is the smallest study?
  • Which is the largest study?
  • How many are statistically significant?
  • Which studies are “large enough”?
what sample size is needed
What sample size is needed?

For disease X the usual mortality rate is 0%

What sample size is needed to detect a reduction in mortality?

  • 100
  • 1,000
  • 100,000
  • 1,000,000
sample size caf rule 1 the 50 50 rule proportions
Sample Size: Café Rule 1The 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 needed1
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 needed2
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?
  • 12% means
    • 12/100 or 24/200 or 48/400
    • and 50 per 417
  • Control + Treatment Groups = 834 in total
systematic review or meta analysis
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 (meta-analysis) may or may not be used to analyze and summarize the results of the included studies.
is the review any good fast appraisal
Is the review any good?FAST appraisal
  • Question – What is the PICO?
  • Finding
    • Did they find most studies?
  • Appraisal
    • Did they select good ones?
  • Synthesis
    • What to they all mean?
  • Transferability of results
why do i need to check the review

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Why do I need to check the review?

Most reviews do not pass minimum criteria

A study of 158 reviews*

  • Only 2 met all 10 criteria
  • Median was only 1 of 10 criteria met

FAST tool = 4 criteria

* McAlister Annals of Intern Med 1999

what it the review question pico

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

What it the review question (PICO)?
  • Population
  • Intervention
  • Comparison
  • Outcome(s)
do pedometers increase activity and improve health
Do pedometers increase activity and improve health?
  • Find: what is your search strategy?
    • Databases?
    • Terms?
    • Other methods?

Do yourself then

Get neighbour’s help

f ind did they find all studies

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

FIND: Did they find all Studies?
  • Check for existing systematic review?
  • Good initial search
    • Terms (text and MeSH)
    • At least 2 Databases: MEDLINE, EMBASE, CINAHL, CCTR, ...
  • Plus a Secondary search
    • Check references of relevant papers & reviews and
    • Find terms (words or MeSH terms) you didn’t use
    • Search again! (snowballing)
is finding all published studies enough

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Is finding all published studies enough?
  • Negative studies less likely to be published than ‘Positive’
  • How does this happen?
  • Follow-up of 737 studies at Johns Hopkins (Dickersin, JAMA, 1992)
    • Positive SUBMITTED more than negative (2.5 times)
registered vs published studies ovarian cancer chemotherapy single v combined

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Registered vs Published StudiesOvarian Cancer chemotherapy: single v combined

Simes, J. Clin Oncol, 86, p1529

registered vs published studies ovarian cancer chemotherapy single v combined1

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Registered vs Published StudiesOvarian Cancer chemotherapy: single v combined

Simes, J. Clin Oncol, 86, p1529

which are biased which ok

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Which are biased? Which OK?
  • All positive studies
  • All studies with more than 100 patients
  • All studies published in BMJ, Lancet, JAMA or NEJM
  • All studies registered studies
publication bias solution

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Publication Bias: Solution
  • All trials registered at inception,
      • The National Clinical Trials Registry: Cancer Trials
      • National Institutes of Health Inventory of Clinical Trials and Studies
      • International Registry of Perinatal Trials
  • Meta-Registry of trial Registries
    • www.controlled-trials.com
appraise select studies

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

APPRAISE & select studies

Did they select only the good quality studies?

miscalculating nnt

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Miscalculating NNT

1. Does the death penalty for miscalculation of an NNT discourage future miscalculation?

2. Should we have the death penalty for miscalculation of NNT?

selective criticism of evidence biased appraisal increases polarization

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Selective Criticism of EvidenceBiased appraisal increases polarization

Lord et al, J Pers Soc Psy, 1979, p2098

selective criticism of evidence

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Selective Criticism of Evidence

28 reviewers assessed one “study” results randomly positive or negative

(Cog Ther Res, 1977, p161-75)

a ssessment how can you avoid biased selection of studies

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Assessment: How can you avoid biased selection of studies?
  • Assessment and selection should be:

Standardized “Objective” OR

Blinded to Results

* assessment of quality blind to study outcome

s ynthesis pooling the results

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Synthesis: pooling the results
meta analysis forest plot

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Meta-analysis (Forest) plot
t ransferable use in my patients

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Transferable? Use in my patients

Is the AVERAGE effect similar across studies?

  • If NO, then WHY?
    • Study methods (RAMbo - biases)
    • PICO (Patients, Intervention, …)
  • If YES, then 2 questions
    • Effect in different individuals?
    • Which version of treatment?
meta analysis forest plot1

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Meta-analysis (Forest) plot

Are the results similar across studies? 3 tests

  • Eyeball” test – do they look they same?
  • Test of “Null hypothesis” of no variation (p-value)
  • Proportion of variation not due to chance (I2)
are these trials different

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Are these trials different?
conclusion ebm and systematic review
EBM (quick & dirty)

Steps

Ask Question

Search

Appraise

Apply

Time: 90 seconds

< 20 articles

This patient survives!

Systematic Review

Steps

Ask Question

Search ++++ x 2

Appraise x 2

Synthesize

Apply

Time: 6 months, team

< 2,000 articles

This patient is dead

ConclusionEBM and Systematic Review

Find a systematic review!! (and appraise it FAST)

pros and cons of systematic reviews
Pros and cons of systematic reviews
  • Advantages
    • Larger numbers & power
    • Robustness across PICOs
  • Disadvantages
    • May conclude small biases are real effects
is the review any good fast appraisal1
Is the review any good?FAST appraisal
  • Question – What is the PICO?
  • Finding
    • Did they find most studies?
  • Appraisal
    • Did they select good ones?
  • Synthesis
    • What to they all mean?
  • Transferability of results
using review results what do i do with my patient

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Using review results: what do I do with my patient?
  • STUDY: meta-analysis of behavioural interventions for insomnia adults
    • “.. confirms the efficacy of behavioral interventions for person with chronic insomnia.“
  • PROBLEM: No regimens for ‘behavioural intervention’ described
    • Author asked: “what specific treatment regime (or regimes) would you recommend based on your review?”
    • Author response: “It was found that cognitive, behavioral and relaxation therapies all in general lead to similar improvements in sleep outcomes---although cognitive approaches might have been a bit better. The references for these studies are found in the article. “

Rx

“Behavioural

Intervention”

summary systematic reviews
Summary: systematic reviews
  • Advantages
    • Larger numbers & power
    • Robustness across PICOs
  • Disadvantages
    • May conclude small biases are real effects
the results are studies similar
The results: Are studies similar?
  • What are the overall results?
  • Similarity of results
    • Heterogeneity statistic
  • Similarity of question (PICO)
    • Your judgement!
traditional cf systematic reviews
Traditional

Many questions

No search methods

No inclusion criteria

No combining studies

Systematic

One question

Explicit search

Explicit inclusion criteria

Combine study results(meta-analysis)

Traditional cf systematic reviews
slide42

Which are

(i) statistically significant * and (ii) Clinically significant +?

(a*+)

(b+)

(c*)

(d)

Minimum clinical

Important difference

No difference

slide43
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
Sample Size: Cafe Rule 2 - continuousthe 17/(SD squared) Rule

For continuous outcomes, number per arm is

17 / (“worthwhile difference” measured in SDs)

slide45

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 treatment is useless
  • there is no point in continuing to develop the treatment
  • the reduction in mortality is so great that we should introduce the treatment immediately
  • we should keep adding cases to the trial until the Normal test for comparison of two proportions is significant
  • we should carry out a new trial of much greater size
are the studies equivalent

FIND

APPRAISE

SYNTHESISE

TRANSFERABLE

Are the studies equivalent?
  • Are variations in results between studies consistent with chance?

(Test of homogeneity: has low power)

  • If NO, then WHY?
    • Variation in study methods (RAMbo - biases)
    • Variation in PICO (Patients, Intervention, …)
is bed rest ever helpful a systematic review of trials
Is bed rest ever helpful?A systematic review of trials*
  • 10 trials of bed rest after spinal puncture
    • no change in headache with bed rest
    • Increase in back pain
  • Protocols in UK neurology units - 80% still recommend bed rest after LPSerpell M, BMJ 1998;316:1709–10
  • …evidence of harm available for 17 years preceding...

*Allen, Glasziou, Del Mar. Lancet, 1999

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