AFP interview Flashcards
hierarchy of evidence
1) Meta-analysis/ Systematic Review
2) RCT
3) Cohort
4) Case control
5) Cross sectional
6) Case series (collection of similar cases)
Meta analysis definiton
An overview of a topic in which the results of all of the included studies are similar enough statistically that the results are combined and analysed as if it were one study.
A meta-analysis uses the quantitative results from the individual studies, pools them together using a statistical method, and produces a new single quantitative result. This new quantitative result is known as the ‘pooled treatment result’and is depicted graphically in a forest plot
Systematic review definition
An overview of primary research on a particular research question that tries to identify, select and appraises all relevant high quality evidence to answer the research question
A disadvantage of meta-analysis & systematic reviews
Relies on published studies –> publication bias
RCT definition
Cohort study
• People are randomly allocated to a treatment or control group
5 advantages of RCTs
- Studies effect
- Has a control group (balances the confounders)
- Randomised
- Powered for analysis
- Blinding
5 disadvantages of RCTs
• Expensive • Time consuming • Volunteer bias • Not realistic clinical practice (e.g frequent follow-ups) • Can be ethically problematic
Cohort study defintion
Longitudinal observational study - follows people with a common exposure (e.g smoking) over time to determine the risk of subsequent disease
5 advantages of Cohort studies
- Studies risk factors (for common outcomes)
- Safe (ethics)
- Match characteristics
- Realistic patients
- Establish timing & directionality of events
5 disadvantages of Cohort studies
• Cannot blind (difficult) • Loss in follow-up (attrition bias) • Expensive • Hidden confounder • Requires large sample sizes or long follow-up for rare diseases
Case control definition
Identifies two groups (with and w/o disease) and looks back for contributing factors
4 advantages of case control studies
- Studies rare outcomes & disorders
- Small sample size required
- Quick & Cheap
- Safe (ethics)
3 disadvantages of case control studies
- Recall bias (retrospective study)
- Selection bias
- Difficult to select control groups
Cross-sectional study defintion
Descriptive study
• ‘Snapshot’ of a population at a given time in which disease and exposure status are measured at the same time
2 advantages of cross-sectional studies
- Quick & Cheap
* Safe (ethics)