What Is a Cohort Study?

A cohort study is to divide a specific population into different subgroups according to whether they are exposed to a suspicious factor or the degree of exposure. Follow-up observation of the occurrence of outcomes (such as diseases) in two or more groups of members, and compare the incidence of outcomes between groups It is an observational research method to determine whether there is a causal relationship and the degree of correlation between these factors and the outcome.

array research

1. Divided into two categories according to specific conditions:

Birth cohort: refers to a group of people born during a specific period;

Exposure queue: Generally refers to a group of people with some common exposure or characteristics, such as a group of people who entered a factory to work in a certain period.

2. According to the time when the crowd enters the queue, it can be divided into two types:

Fixed cohort: It means that the crowd enters the cohort within a certain fixed time or a short period of time, and then follow-up observation of them until the end of the observation period, members did not withdraw for reasons other than the outcome event, and no longer add people Other new players, and keep the queue relatively fixed during the observation period.

Dynamic queue: After a certain queue is determined, the original queue members can continuously withdraw, and new observation objects can be added at any time. ^[1]

The basic principle of cohort research is to select the required research objects in a specific population, based on whether they are currently

1. Belong to observation method;

2. Establish a control group;

3. From cause to effect;

4. Can confirm the causal relationship between exposure and outcome. ^[1]

1. Test the etiology hypothesis;

2. Evaluate the prevention effect;

3. Research the natural history of diseases;

4. Post-marketing monitoring of new drugs. ^[1]

According to the time when the study subject entered the queue and the time when the observation was terminated, it can be divided into

1. Identify research factors;

2. Determine the outcome of the study;