Classes 16-19

Question 1

List study designs from lowest to highest strength of evidence

Answer 1

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

Question 2

Interventional Study designs in order of increasing strength of evidence

Answer 2

Pre-clinical
Phase 1
Phase 2
Phase 3 
Phase 4

Question 3

(T/F) All interventional study designs are analytical studies

Answer 3

True

Question 4

Observational Study designs in order of increasing strength of evidence

Answer 4

Cases (Reports/Series)
Ecological
Cross-Sectional
Case-Control
Cohort

Question 5

(T/F) All observational study designs are analytical studies

Answer 5

False. Only Cross-Sectional, Case-Control, and Cohort studies are analytical studies.

Question 6

Pre-clinical studies

Answer 6

Bench/animal research

Prior to human investigation

Question 7

Phase 1

Answer 7

• Small n (20-80)
• short duration
• First time in humans to assess safety/toxicity
• Also can be used secondarily to assess dosage and pharmacokinetics

Question 8

Phase 2

Answer 8

• 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)

Question 9

Phase 3

Answer 9

• Large n (1000-3000)
• Longer duration (months to a few years)
• Primary purpose to assess efficacy
• Secondary purpose safety

Question 10

Phase 4

Answer 10

• Post marketing
• Primary purpose to assess long term effects (risk & benefits) in diseased patients
• Large n - expand use population

Question 11

Advantages of Interventional trials

Answer 11

• Proves causation

- Only design used by FDA for approval process

Question 12

Disadvantages of Interventional trials

Answer 12

• Cost
• Complexity/Time
• Ethical considerations (Risk vs Benefit)
• Generalizability from restricted inclusion criteria

Question 13

Explanatory Interventional study

Answer 13

• NOT like clinical treatments

- Strict rules - can’t change treatment on patient to patient basis

Question 14

Pragmatic interventional study

Answer 14

• 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

Question 15

Limitations of pragmatic interventional study

Answer 15

Lose researchers control over intervention

Question 16

Simple Interventional study

Answer 16

• Single randomization

- Commonly used to test single hypothesis

Question 17

Factorial Interventional study

Answer 17

• Divides subjects into 2 or more groups then divides those into 2 or more subgroups
• Used to test multiple hypotheses simultaneously

Question 18

Pros of factorial

Answer 18

• Improves efficiency of answering clinical questions

Question 19

Cons

Answer 19

• Increases sample size
• Increases complexity
• Increases risk of drop outs
• May restrict generalizability of results

Question 20

Parallel Interventional study

Answer 20

• Groups simultaneously and exclusively managed

- No switching of intervention groups after initial randomization

Question 21

Cross over Interventional study

Answer 21

Groups serve as own control by crossing over from one interventional to another during study

Question 22

Disadvantages of cross over

Answer 22

• 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)

Question 23

Run-in/Lead-in phase

Answer 23

Subjects blindly given placebo to wash-out effects of anything prior to study

Question 24

Wash-out

Answer 24

Subjects blindly given placebo to wash out effects of previous intervention before starting new intervention

Question 25

Key Difference btw Observational and Interventional studies

Answer 25

Investigator selects interventions and allocates subjects into forced-intervention groups