Classes 16-19 Flashcards
List study designs from lowest to highest strength of evidence
I - In vitro/test tube Am - Animal Research Chris - Case Reports Christopher - Case Series Every other - Ecological Chris - Cross-Sectional Christopher - Case-Control Can - Cohort Immediately - Interventional Suck - Systematic Reviews My dick - Meta-Analyses
Interventional Study designs in order of increasing strength of evidence
Pre-clinical Phase 1 Phase 2 Phase 3 Phase 4
(T/F) All interventional study designs are analytical studies
True
Observational Study designs in order of increasing strength of evidence
Cases (Reports/Series) Ecological Cross-Sectional Case-Control Cohort
(T/F) All observational study designs are analytical studies
False. Only Cross-Sectional, Case-Control, and Cohort studies are analytical studies.
Pre-clinical studies
Bench/animal research
Prior to human investigation
Phase 1
- Small n (20-80)
- short duration
- First time in humans to assess safety/toxicity
- Also can be used secondarily to assess dosage and pharmacokinetics
Phase 2
- Larger n (100-300)
- Short-medium duration
- Expand on safety assessment
- Begin to assess efficacy
- Narrower inclusion criteria (Commonly utilize patients with condition of interest)
Phase 3
- Large n (1000-3000)
- Longer duration (months to a few years)
- Primary purpose to assess efficacy
- Secondary purpose safety
Phase 4
- Post marketing
- Primary purpose to assess long term effects (risk & benefits) in diseased patients
- Large n - expand use population
Advantages of Interventional trials
- Proves causation
- Only design used by FDA for approval process
Disadvantages of Interventional trials
- Cost
- Complexity/Time
- Ethical considerations (Risk vs Benefit)
- Generalizability from restricted inclusion criteria
Explanatory Interventional study
- NOT like clinical treatments
- Strict rules - can’t change treatment on patient to patient basis
Pragmatic interventional study
- Studies that are more applicable to clinical environment
- Usually no placebo - compare two or more real drugs
- Allow co-morbidities
- Allow patient to patient based clinical decisions
Limitations of pragmatic interventional study
Lose researchers control over intervention
Simple Interventional study
- Single randomization
- Commonly used to test single hypothesis
Factorial Interventional study
- Divides subjects into 2 or more groups then divides those into 2 or more subgroups
- Used to test multiple hypotheses simultaneously
Pros of factorial
- Improves efficiency of answering clinical questions
Cons
- Increases sample size
- Increases complexity
- Increases risk of drop outs
- May restrict generalizability of results
Parallel Interventional study
- Groups simultaneously and exclusively managed
- No switching of intervention groups after initial randomization
Cross over Interventional study
Groups serve as own control by crossing over from one interventional to another during study
Disadvantages of cross over
- Only suitable for long term studies
- Duration longer
- Carry over effects (fixed by wash-out)
- Treatment by period interaction (treatment different effects in different time periods)
Run-in/Lead-in phase
Subjects blindly given placebo to wash-out effects of anything prior to study
Wash-out
Subjects blindly given placebo to wash out effects of previous intervention before starting new intervention
Key Difference btw Observational and Interventional studies
Investigator selects interventions and allocates subjects into forced-intervention groups
