cohort study

Question 1

What kind of exposure can you study in cohort study?

Answer 1

Multiple exposures
* Environmental and occupational exposures
* point exposures
* chronic exposures
* Lifestyle risk factors
* Multiple risk behaviors
* Socio-demographic factors
* Medical and pharmaceutical interventions
* Any agent, environment, vector and host factor

Question 2

What kind of outcome can you study in a cohort study?

Answer 2

Multiple outcomes
Morbidity
* Mortality
* Clinical signs and symptoms
* Laboratory makers and biomarkers
* Behavior and behavioral change
* Recurrence and relapse

Question 3

Types of cohort study

Answer 3

closed
enrollment at a closed (fixed) time
* exposure events: infections, lifestyle risk behaviours, etc.
Dynamic
Participants come and ago
Open
continued enrollment
* differential length of follow-up

Question 4

Types of cohort by study design

Answer 4

Prospective cohort
conceptually most straightforward ; enroll them today and follow them overtime
accurate exposure measurment
Historical cohort
exposure is a historical measure; find the exposure in the past and do the analysis now. start with the historical group exposure in the past and follow them over time for the outcome

Question 5

cumulative incidence vs incidence rate

Answer 5

incidence rate - number of outcomes/number of person years at risk ; same person can have a number of outcomes … bout of flu in years followed in a cohort study

Cumulative incidence - one outcome per individual number of persons with the outcome/ number of persons at risk in the candidate population.

Incidence rate is looking at the number of new outcomes but cumulative incidence is looking at the number of persons with the outcome.