The Cochrane Collaboration, 1993

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The Cochrane Collaboration, 1993
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Nordic Cochrane Centre, 1993
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Nordic Cochrane Centre, 2003

• Located in Copenhagen
• Branches in
• Oslo, Helsinki, Moscow
• Contact persons in
• Iceland, Sweden, Poland

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1972Effectiveness and Efficiency

• Archie Cochrane (1909-1988) drew attention to our
  collective ignorance about the effects of health
  care

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1979
It is surely a great criticism of our
profession that we have not organized a critical
summary, by specialty or subspecialty, adapted
periodically, of all relevant randomized
controlled trials. (Archie Cochrane)
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1989

• Effective Care in Pregnancy and Childbirth
• A Guide to Effective Care in Pregnancy and
  Childbirth
• The Oxford Database of Perinatal Trials

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2003

• 49 Review groups
• 12 Cochrane centres
• 10 Methods groups
• 1596 Cochrane Reviews
• 1200 Cochrane Protocols

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July 1999

• Decision to establish the Campbell Collaboration
  - a sibling collaboration to the Cochrane
  Collaboration - to prepare, maintain and
  disseminate systematic reviews of social and
  educational interventions

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Systematic review 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. Meta-analysis The
use of statistical techniques in a systematic
review to integrate the results of included
studies.
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Why do reviews need a protocol?

• ! A review is a retrospective analysis
• ! Potential threats to the validity of a review
  
• - how trials are identified and selected for
  inclusion
• - how their quality is assessed
• - how much weight each one is given
• - how their results are interpreted and combined
• ! Explicit declarations about how these decisions
  will be made can help protect against these
  threats

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Asthma and house dust mites Unsystematic
review In mite-sensitive asthmatics encasing
the mattress was found to significantly reduce
symptoms and bronchial hyperresponsiveness (ref.
to one study) Lancet 1997350(suppl
II)14-7 Cochrane Review of 23 studies
Current chemical and physical methods aimed at
reducing exposure to house dust mite allergens
seem to be ineffective and cannot be recommended
as prophylaxis for mite sensitive
asthmatics. BMJ 1998 and Cochrane Library 1998
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Unsystematic reviews in bleeding oesophageal
varices

• "Injection sclerotherapy controls bleeding in up
  to 95 of cases" (BMJ 19943081213-7)
• "Applied by an experienced team, balloon
  tamponade can achieve control of variceal
  bleeding in up to 90 of cases" (Lancet
  19943431079-4)
• Somatostatin...and analogues...stop variceal
  hemorrhage in up to 80 percent of patients
• (N Engl J Med 2001345669-81)

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Clinical trials

• "30/36 patients (83) receiving placebo stopped
  bleeding" (Hepatology 198910958-61)
• Systematic review, 3 trials
• "we were unable to show a clinical benefit of
  somatostatin" (BMJ 1995310(June 10)1495-8)

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Editorial

• "use vasoactive agents such as the somatostatin
  analogue octreotide to reduce active haemorrhage"
  (BMJ 1996312(May 4)1111-2)
• Cochrane Review, 12 trials
• The effect corresponded to one unit of blood
  saved per patient. It can be discussed whether
  this effect is worthwhile. (Gøtzsche, Cochrane
  Library 2002)

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Human albumin

• Albumin vs no albumin or crystalloids
• 30 trials, 156 deaths among 1419 trial
  participants.
• Risk of death with albumin RR 1.68 (1.26 to
  2.23)
• Hypovolaemia RR 1.46 (0.97 to 2.22)
• Burns RR 2.40 (1.11 to 5.19)
• Hypoalbuminaemia RR 1.69 (1.07 to 2.67)
• These data suggest that for every 17 critically
  ill patients treated with albumin there is one
  additional death.
• BMJ and Cochrane Library 1998

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Routine late ultrasound screening during
pregnancy (after 24 weeks) does not confer
benefit on mother or baby (Cochrane Library,
2002)Not recommended by National Board of
Health in Denmark
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Support during childbirth

• 14 trials, different settings, more than 5000
  women
• Continuous presence of a support person reduced
• - medication for pain relief
• - operative vaginal delivery
• - caesarean delivery
• - a 5-minute Apgar score less than 7
• - length of labour (slightly)
• (Cochrane Library 2002)

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Brief psychological debriefing

• Reviewers' conclusions There is no current
  evidence that psychological debriefing is a
  useful treatment for the prevention of post
  traumatic stress disorder after traumatic
  incidents. Compulsory debriefing of victims of
  trauma should cease.
• ...a tendency that things got worse...
• (Cochrane Library 2002)

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Mortality ascribed to breast cancer after 13 years
P0.007
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Two-County study, Östergötland part

• No. of breast Relative
• cancer deaths risk
• invited control
• Swedish overview 2002 177 190 0.90
• Two-County 2000 167 213 0.76
• Same age group (40-74)
• Same statistics (evaluation model)
• Same follow-up (1.2 vs 1.3 mio women-years)

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The screening lottery

• For every 1,000 women screened for 10 years
• 1 breast cancer death is avoided
• (or the woman dies from something else)
• 5 extra tumorectomies/mastectomies
• 2 extra mastectomies
• gt100 will experience important psychological
  distress for many months because of false
  positive findings

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Screening

• The most balanced and comprehensive information
  on breast cancer screening comes from consumer
  websites
• Websites from cancer charities and governmental
  agencies are persuasive, not informative

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Collaboration with consumers

• Too little focus on harms in health care practice
  and health care research.
• A review which considers only favourable outcomes
  but not proven, suspected and potential adverse
  effects (whether common or rare), is almost bound
  to reach biased conclusions.
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• This source of bias, like others, should be
  minimised in Cochrane Reviews.

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Cochrane Reviews

• Synopsis for consumers (free)
• Abstract (free)
• Body of the review (free in a few countries)

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Cochrane Consumer Network

• Consumer web page
• www.cochraneconsumer.com

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Where is the reliable evidence?
2 million new articles every year
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