Cochrane Stroke group

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Cochrane Stroke group

• Professor Peter Sandercock,
• University of Edinburgh
• Co-ordinating Editor Cochrane Stroke Group

European Masters in Stroke. Krems April 2007
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Three parts

• Introduction to the Cochrane Collaboration
• How to do a Cochrane review
• Analysis subgroup analysis

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Part 1 Introduction to the Cochrane Library
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Levels of evidence
Strongest evidence

• High quality systematic review meta-analysis of
  randomised controlled trials
• Single randomised controlled trial
• Case-control studies or cohort studies
• Non-analytic studies, e.g. case reports, case
  series
• Expert opinion

Weakest evidence
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For every medical question, there is a universe
of relevant evidence
But often, the doctor is only aware of the small
fraction of the evidence illuminated by the
narrow beam of light he uses to search for it
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Cochrane systematic review, a structured process
Systematic review

• Clear question
• Search for ALL relevant trials
• Select trials which meet eligibility criteria
• Extract data from eligible studies
• Synthesis of data (meta-analysis)
• Implications
• For clinical practice
• For research
• Update review every 2 years

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Cochrane Collaboration

• International not-for-profit organisation
• Aim to help people make well- informed decisions
  about healthcare, by
• preparing systematic reviews of the effects of
  health care interventions, published in the
  Cochrane Library
• keeping the reviews up to date
• making the reviews accessible

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Review topics covered by the Cochrane
Neurological Network

• Acquired Metabolic Disorders
• Alcohol and Alcoholism
• Back
• Brain and Spinal Cord Tumors
• Brain and Spinal Injuries
• CSN and Spinal Infection
• Dementia
• Demyelinating Diseases
• Epilepsy
• Intensive Care
• Palliative Care
• Intoxications and Poisonings
• Migraine and Headache
• Motor Neurone Disease

• Movement Disorders
• Neurological Services
• Neuromuscular Disorders
• Neurosurgery
• Nutritional Deficiency Disorders
• Pain
• Peripheral and Cranial Nerve Neuropathies
• Rare and Hereditary Diseases
• Sleep Disorders
• Stroke
• Subarachnoid Haemorrhage
• Symptomatic Treatment

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Cochrane Library Issue 1, 2007contains

• Cochrane Database of Systematic Reviews 3009
  Reviews 1668 protocols for reviews
• Database of quality-assessed Abstracts of Reviews
  of Effects (DARE) 5931 Abstracts
• Cochrane Central Register of Controlled Trials
  (CENTRAL)489000 reports of RCTs and CCTs

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Cochrane Stroke Review Group

• Systematic reviews in stroke
• prevention
• treatment
• rehabilitation
• 300 reviewers from 21 countries
• Trials register gt 11,000 references to 4,800
  trials
• Published
• 96 completed reviews
• 30 protocols for future reviews

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Now gt 11,000 stroke trials in register!
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Impact of Cochrane Stroke reviews

• Cochrane reviews cited in national stroke
  guidelines and policy documents in UK, Europe,
  USA, Australia, New Zealand Singapore
• UK National Stroke Guideline states 'In each
  hospital, the neurologist or physician with
  special responsibility for stroke should review
  the Cochrane Library regularly.
• Cochrane Corner now a feature in Stroke

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Framing your question (PICO)

• Patient (eg acute phase of stroke)
• Intervention (drug, procedure etc)
• Comparison (placebo, open control, standard
  therapy etc)
• Outcome (death, recurrent stroke, disability)

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Example

• P in the first few days after stroke,
• I do compression stockings,
• C compared with no stockings,
• O prevent deep vein thrombosis and pulmonary
  embolism?

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Other aspects of the question

• Is the question important?
• Burden of disease
• How common is the problem?
• How much death/ disability does it cause?
• What impact will the treatment have on burden?
• How feasible is the treatment?
• A small effect in a large of patients will have
  greater impact than a large effect in a small

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Benefits of stroke units, thrombolysis and
aspirin in UK (assuming 100,000 strokes per year)

• Treatment no. benefit
  no.
• treated per 1000 avoiding
  treated
  death/dep.
• Thrombolysis 5,000 60
  300
• Aspirin 80,000 13 1000
• Stroke unit 60,000 62 3700
• estimates of benefit (avoiding death or
  dependency)
• from 3 relevant Cochrane systematic reviews

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Other aspects of the question

• Should it be broad or focused?
• Broad Anticoagulants for acute stroke
• Focused low molecular weight heparin for DVT
  prophylaxis

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Other aspects of the question

• Im not interested in treatment what areas are
  not currently covered by Cochrane?
• (Diagnostic test accuracy coming soon!)
• Epidemiology
• Prognosis
• What type of evidence to review?
• Strictly randomised trials hard work
• Controlled trials (treatment and control groups,
  but not selected by random allocation) hard work
  difficult!
• Observational studies very hard work very
  difficult!

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What are the questions in acute stroke?

• Please spend a moment to think about a question
  you have about the management of acute stroke
• Please express it in terms of PICO
• We can then see whether it is the type of
  question that can be answered by the Cochrane
  Library
• If not, how might it be answered?

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Summary

• Systematic reviews are a very useful tool for
  making sense of the available evidence
• The Cochrane Library is an excellent source of
  systematic reviews relevant to medicine and
  neurology
• The Cochrane Collaboration is
• mainly focused on evaluating treatments and the
  organisation of care
• now beginning to work on diagnostic tests