AUSTRALASIAN
COCHRANE CENTRE
To Cochrane or not:
that's the question
1
Professor Hesham Al-Inany
Editor, Cochrane Menstrua...
AUSTRALASIAN
COCHRANE CENTRE
Preparing, maintaining and disseminating systematic
reviews of the effects of health care
THE...
AUSTRALASIAN
COCHRANE CENTRE
Antenatal corticosteroids for preterm
birth
• Survey:
• 1980 RCOG survey: 42%
• 1984 Belgium ...
AUSTRALASIAN
COCHRANE CENTRE
Learning objectives
 Why are systematic reviews important?
 Why Cochrane systematic reviews...
AUSTRALASIAN
COCHRANE CENTRE
How do we treat our patients?
 Using evidence from high quality research to
answer specific ...
AUSTRALASIAN
COCHRANE CENTRE
For example:
In women with infertility does acupuncture
improve pregnancy outcomes ?
AUSTRALASIAN
COCHRANE CENTRE
7
RCT : Gold standard
Participants
RandomlyAssigned
Intervention Group
Control Group
Follow-u...
AUSTRALASIAN
COCHRANE CENTRE
But there are many RCTs on this topic
 Some with conflicting results
 Some with small numbe...
AUSTRALASIAN
COCHRANE CENTRE
Why are systematic
reviews useful?
AUSTRALASIAN
COCHRANE CENTRE
Systematic review
 Uses tools to summarise the results of a number
of trials/studies
 Syste...
AUSTRALASIAN
COCHRANE CENTRE
Advantages
• To increase power, Many individual studies
are too small to detect small effects...
AUSTRALASIAN
COCHRANE CENTRE
Review : Steff
Comparison: 01 Absence of evidence and Evidence of absence
Outcome: 01 Increas...
AUSTRALASIAN
COCHRANE CENTRE
1. Clear objectives stated with a well formulated
clinical question
2. Inclusion and exclusio...
AUSTRALASIAN
COCHRANE CENTRE
1. Clearly stated objective with clinical
question
Participants Intervention Comparison Outco...
AUSTRALASIAN
COCHRANE CENTRE
2. Inclusion and exclusion criteria pre-stated
Participants Intervention Comparison Outcome
I...
AUSTRALASIAN
COCHRANE CENTRE
3. Comprehensive search for all
studies
All databases are searched to avoid
publication bias?...
AUSTRALASIAN
COCHRANE CENTRE
Publication Bias
 Research with statistically significant
results is more likely to be submi...
AUSTRALASIAN
COCHRANE CENTRE
Advanced ovarian cancer
Comparison: combination chemotherapy versus
single chemotherapy
Publi...
AUSTRALASIAN
COCHRANE CENTRE
Not restricted to English language
AUSTRALASIAN
COCHRANE CENTRE
4. Systematic approach
Independent tasks by 2 or more reviewers:
 Selection of studies for i...
AUSTRALASIAN
COCHRANE CENTRE
5. Excluded studies listed
 All excluded studies included in a table
 Reasons given for exc...
AUSTRALASIAN
COCHRANE CENTRE
6. Pooling of results using meta-analysis
if appropriate and possible
What is a meta-analysis...
AUSTRALASIAN
COCHRANE CENTRE
Why do we need it
 To avoid Type II error: Investigators did
not detect a difference when a
...
AUSTRALASIAN
COCHRANE CENTRE
Review : Steff
Comparison: 01 Absence of evidence and Evidence of absence
Outcome: 01 Increas...
AUSTRALASIAN
COCHRANE CENTRE
Graphic
Display:
ß blockers in
secondary
prevention after
myocardial
infarction.
AUSTRALASIAN
COCHRANE CENTRE
Cumulative Meta-analysis
AUSTRALASIAN
COCHRANE CENTRE
Meta-analysis vs. a “Mega-study”
Single large studies are liable to:
 Long duration
 Huge f...
AUSTRALASIAN
COCHRANE CENTRE
 Why are systematic reviews important?
 Why Cochrane systematic reviews?
 How to prepare a...
AUSTRALASIAN
COCHRANE CENTRE
Advantages of Cochrane reviews
 Updating of reviews regularly
 Methodologically robust
 Le...
AUSTRALASIAN
COCHRANE CENTRE
How do (Cochrane) systematic reviews
reduce bias?
 Prestated methods published
 Limit publi...
AUSTRALASIAN
COCHRANE CENTRE
Studies with funding bias are more likely to have
favourable results (Lundh et al 2012)
 Add...
AUSTRALASIAN
COCHRANE CENTRE
“..we observed far superior
reporting standards of Cochrane
reviews compared to non-
Cochrane...
AUSTRALASIAN
COCHRANE CENTRE
Our structure
• more than 27,000 people in over 100 countries
 almost all volunteers
• decen...
AUSTRALASIAN
COCHRANE CENTRE
Cochrane centers all over the world
AUSTRALASIAN
COCHRANE CENTREwww.thecochranelibrary.
AUSTRALASIAN
COCHRANE CENTRE
Cochrane Reviews
Randomised
controlled trials
Methodology
papers
AUSTRALASIAN
COCHRANE CENTRE
AUSTRALASIAN
COCHRANE CENTRE
AUSTRALASIAN
COCHRANE CENTRE
AUSTRALASIAN
COCHRANE CENTRE
Displaying results graphically
 Revman software produces forest plots
AUSTRALASIAN
COCHRANE CENTRE
there’s a label to tell
you what the comparison
is and what the outcome
of interest is
AUSTRALASIAN
COCHRANE CENTRE
At the bottom there’s
a horizontal line. This
is the scale measuring
the treatment effect.
AUSTRALASIAN
COCHRANE CENTRE
The vertical line in the
middle is where the
treatment and control
have the same effect –
the...
AUSTRALASIAN
COCHRANE CENTRE
For each study
there is an id
The data for
each trial
are here, divided
into the experimental...
AUSTRALASIAN
COCHRANE CENTRE
•Each study is given a blob, placed where the data measure the effect.
•The size of the blob ...
AUSTRALASIAN
COCHRANE CENTRE
The pooled analysis is given a diamond shape
where the widest bit in the middle
is located at...
AUSTRALASIAN
COCHRANE CENTRE
Reading the graphs
What
outcome?
What
measure of
effect size?
The
events
The
pooled
ORs
And c...
AUSTRALASIAN
COCHRANE CENTRE
Reading the graphs
What
measure of
effect size?
And confidence
intervals
The
pooled
ORs
Heter...
AUSTRALASIAN
COCHRANE CENTRE
Limitations ???
 Takes long time to publish and huge
effort to be done
 Authors may lose in...
AUSTRALASIAN
COCHRANE CENTRE
Practical tips for new comers
 no specific criteria to be an author
 Determine which field ...
AUSTRALASIAN
COCHRANE CENTRE
The life cycle of a Cochrane review
Title
(registered)
Prepare
Protocol
Register
Protocol
Sys...
AUSTRALASIAN
COCHRANE CENTRE
What support is available?
 an on-line systematic review training
programmes can be accessed...
AUSTRALASIAN
COCHRANE CENTRE
The end.....
54
http://www.cochrane.org/about-us
/newcomers-guide.
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To Cochrane or not: that's the question

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the role of Cochrane collaboration and specifically the menstrual disorder & subfertility group is illustrated . simple explanation how to use cochrane reviews is done.

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To Cochrane or not: that's the question

  1. 1. AUSTRALASIAN COCHRANE CENTRE To Cochrane or not: that's the question 1 Professor Hesham Al-Inany Editor, Cochrane Menstrual Disorders & Subfertility Group Editor, British Journal of Obstetrics & gynecology Cairo University Egypt
  2. 2. AUSTRALASIAN COCHRANE CENTRE Preparing, maintaining and disseminating systematic reviews of the effects of health care THE COCHRANE COLLABORATION
  3. 3. AUSTRALASIAN COCHRANE CENTRE Antenatal corticosteroids for preterm birth • Survey: • 1980 RCOG survey: 42% • 1984 Belgium : 32% • 1990 UK centers : 58% • 1992 US Obs: 8-34% • NIH : •”corticosteroid Rx is indicated for women at risk of premature delivery ……….. and will result in a substantial decrease in neonatal morbidity and mortality as well as substantial savings”
  4. 4. AUSTRALASIAN COCHRANE CENTRE Learning objectives  Why are systematic reviews important?  Why Cochrane systematic reviews?  How to join for a Cochrane systematic review? 4
  5. 5. AUSTRALASIAN COCHRANE CENTRE How do we treat our patients?  Using evidence from high quality research to answer specific questions
  6. 6. AUSTRALASIAN COCHRANE CENTRE For example: In women with infertility does acupuncture improve pregnancy outcomes ?
  7. 7. AUSTRALASIAN COCHRANE CENTRE 7 RCT : Gold standard Participants RandomlyAssigned Intervention Group Control Group Follow-up Follow-up Intervention Group Control Group
  8. 8. AUSTRALASIAN COCHRANE CENTRE But there are many RCTs on this topic  Some with conflicting results  Some with small number of participants
  9. 9. AUSTRALASIAN COCHRANE CENTRE Why are systematic reviews useful?
  10. 10. AUSTRALASIAN COCHRANE CENTRE Systematic review  Uses tools to summarise the results of a number of trials/studies  Systematic and scientific methodology  Helpful in clinical decision making
  11. 11. AUSTRALASIAN COCHRANE CENTRE Advantages • To increase power, Many individual studies are too small to detect small effects, but when several are combined there is a higher chance of detecting an effect. • To improve precision: The estimation of an intervention effect can be improved when it is based on more data.
  12. 12. AUSTRALASIAN COCHRANE CENTRE Review : Steff Comparison: 01 Absence of evidence and Evidence of absence Outcome: 01 Increasing the amount of data... Study Treatment Control OR (fixed) OR (fixed) or sub-category n/N n/N 95% CI 95% CI 1 study 10/100 15/100 0.63 [0.27, 1.48] 2 studies 20/200 30/200 0.63 [0.34, 1.15] 3 studies 30/300 45/300 0.63 [0.38, 1.03] 4 studies 40/400 60/400 0.63 [0.41, 0.96] 5 studies 50/500 75/500 0.63 [0.43, 0.92] 0.1 0.2 0.5 1 2 5 10 Favours treatment Favours control In the example below, as more data is included, the overall odds ratio remains the same but the confidence interval decreases. It is not true that there is ‘no difference’ shown in the first rows of the plot – there just isn’t enough power to show a statistically significant result.
  13. 13. AUSTRALASIAN COCHRANE CENTRE 1. Clear objectives stated with a well formulated clinical question 2. Inclusion and exclusion criteria stated 3. Comprehensive search strategy 4. Systematic approach with all relevant studies 5. Excluded studies listed with reasons 6. Trial results are pooled if possible (meta-analysis) Features not in narrative reviews
  14. 14. AUSTRALASIAN COCHRANE CENTRE 1. Clearly stated objective with clinical question Participants Intervention Comparison Outcome In women with infertility does acupuncture improve pregnancy outcomes ?
  15. 15. AUSTRALASIAN COCHRANE CENTRE 2. Inclusion and exclusion criteria pre-stated Participants Intervention Comparison Outcome In women with infertility does acupuncture treatment improve pregnancy outcomes ? • Women <45 yo • Infertility for > 1 yr • No other Rx or ART? Acupunture Live birth rate Adverse events Sham Acupuncture or no treatment
  16. 16. AUSTRALASIAN COCHRANE CENTRE 3. Comprehensive search for all studies All databases are searched to avoid publication bias? MEDLINE, EMBASE, CINHAL and others
  17. 17. AUSTRALASIAN COCHRANE CENTRE Publication Bias  Research with statistically significant results is more likely to be submitted for publication and more likely to be published.
  18. 18. AUSTRALASIAN COCHRANE CENTRE Advanced ovarian cancer Comparison: combination chemotherapy versus single chemotherapy Published trials 0.7 1 1.3 Registered trials Simes 1987 Outcome: mortality
  19. 19. AUSTRALASIAN COCHRANE CENTRE Not restricted to English language
  20. 20. AUSTRALASIAN COCHRANE CENTRE 4. Systematic approach Independent tasks by 2 or more reviewers:  Selection of studies for inclusion and tabulated  Data extraction  Quality assessment  Data entry Disagreements resolved by 3rd party
  21. 21. AUSTRALASIAN COCHRANE CENTRE 5. Excluded studies listed  All excluded studies included in a table  Reasons given for exclusion  Transparency minimises bias
  22. 22. AUSTRALASIAN COCHRANE CENTRE 6. Pooling of results using meta-analysis if appropriate and possible What is a meta-analysis?  A statistical tool to combine results of studies  Using Revman software (free to download)  Valuable way to display a summary of the trials
  23. 23. AUSTRALASIAN COCHRANE CENTRE Why do we need it  To avoid Type II error: Investigators did not detect a difference when a difference actually exists
  24. 24. AUSTRALASIAN COCHRANE CENTRE Review : Steff Comparison: 01 Absence of evidence and Evidence of absence Outcome: 01 Increasing the amount of data... Study Treatment Control OR (fixed) OR (fixed) or sub-category n/N n/N 95% CI 95% CI 1 study 10/100 15/100 0.63 [0.27, 1.48] 2 studies 20/200 30/200 0.63 [0.34, 1.15] 3 studies 30/300 45/300 0.63 [0.38, 1.03] 4 studies 40/400 60/400 0.63 [0.41, 0.96] 5 studies 50/500 75/500 0.63 [0.43, 0.92] 0.1 0.2 0.5 1 2 5 10 Favours treatment Favours control
  25. 25. AUSTRALASIAN COCHRANE CENTRE Graphic Display: ß blockers in secondary prevention after myocardial infarction.
  26. 26. AUSTRALASIAN COCHRANE CENTRE Cumulative Meta-analysis
  27. 27. AUSTRALASIAN COCHRANE CENTRE Meta-analysis vs. a “Mega-study” Single large studies are liable to:  Long duration  Huge funding a drug that reduces mortality by 10% from myocardial infarction may need a study including 10.000 patients
  28. 28. AUSTRALASIAN COCHRANE CENTRE  Why are systematic reviews important?  Why Cochrane systematic reviews?  How to prepare a protocol for a Cochrane systematic review 28
  29. 29. AUSTRALASIAN COCHRANE CENTRE Advantages of Cochrane reviews  Updating of reviews regularly  Methodologically robust  Less likely to be biased
  30. 30. AUSTRALASIAN COCHRANE CENTRE How do (Cochrane) systematic reviews reduce bias?  Prestated methods published  Limit publication bias (very comprehensive search)  Limit commercial and industry sponsorship of reviews
  31. 31. AUSTRALASIAN COCHRANE CENTRE Studies with funding bias are more likely to have favourable results (Lundh et al 2012)  Add reviews on this topic
  32. 32. AUSTRALASIAN COCHRANE CENTRE “..we observed far superior reporting standards of Cochrane reviews compared to non- Cochrane therapeutic ones.” “For therapeutic reviews, all the Cochrane ones reported assessing the quality of included studies whereas only half of the non- Cochrane did.” “The seven industry supported reviews that had conclusions recommended the experimental drug without reservations, compared with none of the Cochrane reviews, although the estimated treatment effect was similar on average Better quality reviews
  33. 33. AUSTRALASIAN COCHRANE CENTRE Our structure • more than 27,000 people in over 100 countries  almost all volunteers • decentralised structure  52 Cochrane Review Groups (CRGs) • specific areas of health care • first point of contact for authors • international and multidisciplinary • largely funded by government grants
  34. 34. AUSTRALASIAN COCHRANE CENTRE Cochrane centers all over the world
  35. 35. AUSTRALASIAN COCHRANE CENTREwww.thecochranelibrary.
  36. 36. AUSTRALASIAN COCHRANE CENTRE Cochrane Reviews Randomised controlled trials Methodology papers
  37. 37. AUSTRALASIAN COCHRANE CENTRE
  38. 38. AUSTRALASIAN COCHRANE CENTRE
  39. 39. AUSTRALASIAN COCHRANE CENTRE
  40. 40. AUSTRALASIAN COCHRANE CENTRE Displaying results graphically  Revman software produces forest plots
  41. 41. AUSTRALASIAN COCHRANE CENTRE there’s a label to tell you what the comparison is and what the outcome of interest is
  42. 42. AUSTRALASIAN COCHRANE CENTRE At the bottom there’s a horizontal line. This is the scale measuring the treatment effect.
  43. 43. AUSTRALASIAN COCHRANE CENTRE The vertical line in the middle is where the treatment and control have the same effect – there is no difference between the two
  44. 44. AUSTRALASIAN COCHRANE CENTRE For each study there is an id The data for each trial are here, divided into the experimental and control groups This is the % weight given to this study in the pooled analysis
  45. 45. AUSTRALASIAN COCHRANE CENTRE •Each study is given a blob, placed where the data measure the effect. •The size of the blob is proportional to the % weight •The horizontal line is called a confidence interval and is a measure of how we think the result of this study might vary with the play of chance. •The wider the horizontal line is, the less confident we are of the observed effect. The label above the graph tells you what statistic has been used The data shown in the graph are also given numerically
  46. 46. AUSTRALASIAN COCHRANE CENTRE The pooled analysis is given a diamond shape where the widest bit in the middle is located at the calculated best guess (point estimate), and the horizontal width is the confidence interval Definition of a 95% confidence interval: If a trial was repeated 100 times, then 95 out of those 100 times, the best guess (point estimate) would lie within this interval.
  47. 47. AUSTRALASIAN COCHRANE CENTRE Reading the graphs What outcome? What measure of effect size? The events The pooled ORs And confidence intervals weighting?
  48. 48. AUSTRALASIAN COCHRANE CENTRE Reading the graphs What measure of effect size? And confidence intervals The pooled ORs Heterogeneity The events
  49. 49. AUSTRALASIAN COCHRANE CENTRE Limitations ???  Takes long time to publish and huge effort to be done  Authors may lose interest in updating SR  Not considered for PhD as main research (reviewer not author ??) 49
  50. 50. AUSTRALASIAN COCHRANE CENTRE Practical tips for new comers  no specific criteria to be an author  Determine which field of interest  Choose a very specific point  formulate a question  make a quick search for RCTs  preferably not more than 6 RCTs
  51. 51. AUSTRALASIAN COCHRANE CENTRE The life cycle of a Cochrane review Title (registered) Prepare Protocol Register Protocol Systematic Review Review online Time Frame 6 Months 12 Months Lifelong editorial + external review searches inclusions quality data extraction meta-analysis editorial + external review outside comments and criticisms new data 2 or more reviewers
  52. 52. AUSTRALASIAN COCHRANE CENTRE What support is available?  an on-line systematic review training programmes can be accessed at:  http://www.cochrane-net.org/openlearning  http://www.cochrane.org/training/authors
  53. 53. AUSTRALASIAN COCHRANE CENTRE The end..... 54 http://www.cochrane.org/about-us /newcomers-guide.

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