Research study designs

Question 1

Questions asked in each phase of drug development

Answer 1

Phase I: Is the drug safe?

• healthy volunteer
• Pharmacokinetics
• AE

Phase II: dose the drug work?

• pts w/ dz
• efficacy of tx
• appropriate dosing
• AE

Phase III: does the drug work better?

FDA approval

Phase IV: Postmarketing surveillance
-less common AE
Long term effects

Question 2

Meta-analysis

Answer 2

Combines data from many studies
Increases statistical power
Pooling studies – selection bias creeps in

Quality as good as individual study quality

Question 3

Case control study

Answer 3

W/dz and w/o dz
Look for exposure risk – assoc
Retrospective

Observational – no intervention

-> Odds Ratio
Odds dz and no dz had exposure: A/C / B/D
Odds dz of exposed vs dz of unexposed: A/B / C/D

Question 4

Cohort study

Answer 4

Common exposure compared to no exposure as control
Observational
Retro or prospective

-> Relative risk
Risk ratio: A/A+B / C/C+D
Rate of dz in exposure group/rate of dz in unexposed group

How many times greater risk bad outcome happens in exposed group

Question 5

Cross-sectional study

Answer 5

Population at 1 point in time
Snapshot of large population

Prevalence
Observational

Can’t tell you:
Incidence
Increase or decrease in prevalence
How exposures/outcomes related over time
Can’t give causality

Question 6

Twin concordance study

Answer 6

Rates/traits of dz in identical twins and in fraternal twins to measure heritability

Question 7

Adoption study

Answer 7

Genetics vs environment factors

Twins raised in separate homes

Question 8

Controlled

Answer 8

Experimental group receives experimental tx

Control group: placebo or comparison drug that’s well known

Question 9

Randomized

Answer 9

Random assignment to experimental or control group

Limits bias

Question 10

Double blinded

Answer 10

Participant and investigator don’t know what they are getting/giving