Intervention Studies Flashcards
What are different forms of research investigating the effects of intervention?
- Case study/series
- Controlled trials
- Randomised trials - Systematic reviews
What are the characteristics of a case series?
- Prone to bias by natural recovery
- Statistical regression
- Placebo effects
- Polite patients
What are the characteristics of controlled studies?
Prone to selection bias
What are the characteristics of randomised trials?
- Groups are comparable at baseline
- Give us valid information about average effects of interventions
What are the characteristics of systematic reviews?
Provide comprehensive transparent and minimally biased overviews of intervention effects (+/- meta-analysis)
Why do studies have inconsistent results?
- Bias: Minimised through careful research design
- Differences in:
types of patients included
the way the treatment was administered
the way the outcomes were measured
What are the causes of bias in intervention studies?
- Natural recovery
- Measurement bias
- Statistical regression
- Polite patients
- Placebo/Hawthorne effects
- Attrition bias
- Recall bias
What is natural recovery?
Condition resolves without intervention
What is measurement bias?
Awareness of group may effect measurement
What is statistical regression (regression to the mean)?
Patients present for therapy when their condition is severe, random reductions will likely lead to improvement
How do polite patients cause bias?
Exaggerate recovery especially when asked by surgeon
What are placebo/Hawthorne effects?
Ritual of interventions or expectation/attention
produces improvement
What is attrition bias?
Withdrawal from the trial
What is recall bias?
Memory for extreme events and selective memories
What factors threaten the internal validity of a study?
- Bias
- Chance
- Confounding
