40. SYSTEMATIC AND META-ANALYSIS STUDIES Flashcards
- What are the aims of Evidence Based Medicine?
IT AIMS TO OPTIMISE MEDICAL PRACTICE:
- it aims to optimise decision making
- it does this by emphasising the use of evidence
- this evidence comes from well designed and conducted
research
MANY STUDIES:
- will have to confirm the sae results
- different literatures will have to have the same
conclusions
- How do we classify Medical Evidence?
- we classify it by its scientific strength
- only the strongest types of research can yield strong
recommendations
- What is the Hierarchy of Evidence?
THIS LIST GOES FROM THE STRONGEST EVIDENCE TO THE WEAKEST:
1. Systematic Reviews
2. Randomised Control Trials
3. Cohort Studies
4. Case-Control Studies
5. Case Series and Case Reports
6. Editorials and Expert Opinions
- What are Editorials and Expert studies an example of?
- they are an example of Descriptive Studies
- Which type of time-based studies provide stronger evidence?
- Prospective studies
- rather than Retrospective
- What is the advantage of High Quality Research?
IT HAS THE ABILITY
- to change or to improve current clinical practice
IT ENCOURAGES HEALTH CARE PROFESSIONALS
- and systems
- to use treatments that are more clinical and cost
effective
IT ENCOURAGES HOSPITALS
- to remove and stop funding practices that do not meet
the objectives
- What kind of results can Weaker Study Types bring?
- they bring only weak recommendations
- What are three examples of Observational Studies?
- Cohort Studies
- Case Control Studies
- Cross-Sectional Studies
- What is a Systematic Review?
- it is a review of a clearly formulated question
- What are two characteristics of Systematic Reviews?
- THEY ARE SYSTEMATIC AND EXPLICIT METHODS
- of identifying, selecting and critically evaluate
research - THEY COLLECT AND ANALYSE DATA
- from the studies that are included in the review
- What is Meta-Analysis?
- it is an example of a Statistical Method
- it may be used to analyse and summarise the results of
the studies included in the Systematic Review - it is an optional part of the Systematic Review
WE PUT THE SYSTEMATIC REVIEW AND THE META-ANALYSIS TOGETHER:
- to create a quantitative amount to analyse
- What are the steps involved in a Systematic Review?
- FORMULATE A REVIEW QUESTION
- FIND THE STUDIES YOU WANT TO USE
- SELECT AND EVALUATE THE CHOSEN STUDIES
- evaluate them in terms of their value - SUMMARISE AND GROUP TOGETHER THE RESULTS
- INTERPRET AND APPLY THE RESULTS
- What is the Framework we use when we look at a Research Question?
- PICOS
- P:
- the Types of Participants
- I:
- the Types of Intervention
- this refers to the Exposure
- C:
- Comparators
- O:
- Types of Outcomes
- S:
- Types of studies
- the studies can be observational or experimental
- Define: Meta-Analysis.
- this is the Statistical Component of a Systematic Review
IT MAY OR MAY NOT ALWAYS BE POSSIBLE OR APPROPRIATE:
- to conduct as part of the systematic review
A META-ANALYSIS IS WHEN:
- we pool together results
- then we measure the overall and pooled association
- What does a Meta-Analysis show us?
- it shows is if there is an association between the
Exposure and the Outcome - this ensures that the association is not a Result of
Chance
- What does this Logo show?
- this is the Cochrane Collaboration (1993)
- it encouraged the growth of Meta-Analysis in Medical
Research
- Why should be conduct a Meta-Analysis as part of a Systematic Review?
- a single study may not give very precise results about
the effects of a treatment
COMBINING THE RESULTS FROM SEVERAL STUDIES:
- gives us more precise estimates
- it generalises the results to different countries and
settings
- List 6 reasons why Meta-Analysis is important?
- RESEARCHERS PUT LITTLE FAITH IN A SINGLE STUDY
- that outlines the effect of a treatment
- this is regardless of how statistically significant the
data is - IT ALLOWS US TO WRITE A NARRATIVE REVIEW
- this reviews of the quality of the study
- this helps to explain why the association behaved as
it did in the study
- EACH STUDY
- produces a different estimate of the magnitude
- Meta-Analysis allows us to find an average - IT HELPS RESEARCHERS TO UNDERSTAND
- which effects have a real impact on the patient - IT COMBINES THE EFFECTS FROM ALL THE STUDIES
- this gives an overall mean effect
- it gives generalised important statistics
- What is the aim of Meta-Analysis?
- to obtain the magnitude of an effect
- and to do this with precision
- What are the reasons for not performing a
Meta-Analysis?
- THE DATA
- is not in a suitable format - THE STUDIES ARE POOR QUALITY
- they are at risk of being biased - HETEROGENEITY STUDIES
- are not sufficiently similar - HETEROGENEITY STUDIES CAN BE DIFFERENT IN:
- the populations
- interventions
- outcome definitions
- effect estimates
- What is Quality Assessment?
- this is the critical evaluation of the results
- it decides what is a good or a bad study
- it decides which study should be used more than
others - it chooses a reliable study
THE CONCLUSIONS OF QUALITY ASSESSMENT:
- are based in the quality of the studies
- Why are Published Effects of a treatment often biased?
- the meta-analysis will only reflect what is published
- statistically significant results are more likely to be
published - this leads to high bias levels being present
- Define: Publication Bias.
- this is the selected publication of studies
- What are some causes of Publication Bias?
- INVESTIGATORS
- fail to report completed studies - INVESTIGATORS
- fail to report studies that show no effect - INVESTIGATORS
- can publish a limited number of small trials that only
show benefits - BAD PHARMA
- are pharmaceutical companies that suppress
evidence that goes against their agenda
