Systematic Reviews Flashcards
(11 cards)
What is the hierarchy of evidence?
Strongest-Weakest:
Meta analyses and systematic reviews
Randomised control trials
Cohort studies
Case-control studies
Cross sectional studies
Animal trials and in vitro studies
Case reports, opinion papers and letters
What is a systematic review?
A comprehensive search of all the relevant studies on the specific topic. Those identified are appraised and synthesised according to a predetermined and explicit method.
A systematic review attempts to collate all empirical evidence that fits pre-specified eligibility criteria to answer a specific research question.
How do systematic reviews minimise bias?
Use explicit, systematic methods. E.g. not missing out any key papers
Drawbacks of systematic reviews
Availability of systematic reviews bear witness to the maturity of a given field- if there are no trials there is not much point doing a systematic review.
Advantages of systematic reviews with broad research question
If you have a broad research question, can get a comprehensive summary of all the evidence, findings likely to be generalisable.
What does a systematic review need?
A clear research question
Set of protocol prior to review
Clear explicit search strategy and terms
Inclusion criteri- set of explicit statements to determine relevance to research question e.g. only interested in papers from the last 20 years
Synthesis of results
Reviews must assess the quality of the studies they have found. Use this to assign weight to study.
Next step if you have enough evidence is meta analysis take all evidence from all papers and run statistical analysis.
Disadvantage of systematic reviews with broad research question
May ‘lump’ interventions together that are heterogenous (varied in content)
May be a lot of studies to manage difficult for narrative synthesis
Advantage of a systematic review with a narrow research question
More discrete and manageable inclusion criteria
Less heterogeneity. So generalisable to specific group you are interested in not necessarily general population
Disadvantage of systematic review with narrow research question
May be too few Studies to provide meaningful result although this can be useful evidence of ‘gap’. It may not be generalisable to all
Where to find systematic reviews?
In published literature and review databases e.g. The Cochrane Library, Centre for Reviews and Dissemination, What Works Clearing House, The Campbell Collaboration, EPPI Centre
What is the Cochrane Collaboration?
An international nonprofit and independent organisation dedicated to making up-to-date accurate information about the effects of healthcare.
It produces and disseminates reviews of healthcare interventions and promotes the search for evidence in the form of clinical trials and other studies of intervention. The major product of the collaboration is the Cochrane database of systematic reviews which is published quarterly as part of the Cochrane library.
