Objective
Every experiment starts with a research question, which is stated as the study objective - the objective is whatever is going to be assessed or measured
Example:
- Experiment: test new drug for migraine prophylaxis (prevention)
- Primary Objective: does drug A reduce frequency of migraines
Outcomes
specific assessments designed to help inform a study objective
(outcomes get you to objective - help you answer the research question)
1 or 2 primary outcomes that decide the success of your study
Examples:
- Change from baseline to week 24 in monthly migraine days (primary)
- Number of patients with a migraine 1 day after their dose
of Drug A
Enrollment
Patients that are recruited for study
Intervention group
Gets treatment
Control group
Does not get treatment
Randomization
Random allocation of participants to treatment and control group
Stratification factors
Want to keep t and c groups balanced for baseline characteristics - helps randomization be balanced
Allocation concealment
Concealing which group the patient has been allocated to
Blinding
Matching control to treatment
Parallel control group
treatment and control groups observed at same time
Historical control group
control group taken from old study
Active treatment
active established drug thats given to control group
Prospective study
looks forward - watches for outcomes like the development of a disease
- relates the outcome to suspected risk or protection factors
Retrospective study
looks backward - outcome established at the start of the study; examines past exposures to suspected risk or protection factors
Historical control
the outcomes of the intervention group are compared to results from a comparable group of patients whose data is retrieved from a database from the past
Reasons to choose a historical control
Reasons not to use historical control
Crossover designs
all participants are exposed to all controls and interventions in the trial - patients serve as their own control - takes individual variability out of the eqn
Withdrawal studies
participants on a particular treatment are taken off therapy or have their dosage reduced
Cohort study
observing a group/cohort over time
Cohort studies advantages
Cohort studies disadvantages
Prospective Cohort Studies
Retrospective Cohort Studies
Case-control studies
compare patients with a disease/outcome of interest (case) with patients who dont have it (control)
Difference between case-control studies and cohort studies
Case-control studies identify subjects by outcome status at the outset of the investigation