How is a case-control study different from a cohort study?
Table of Contents
- 1 How is a case-control study different from a cohort study?
- 2 Why is a cohort study superior to a case-control study?
- 3 Why is it important to match case subjects and control subjects so closely in a case control study?
- 4 What are the advantages and disadvantages of case control vs cohort studies?
- 5 What is measure Association?
- 6 Why is relative risk not used in case-control studies?
- 7 What is a case-control study?
- 8 What is the difference between case study and cohort study?
How is a case-control study different from a cohort study?
Whereas the cohort study is concerned with frequency of disease in exposed and non-exposed individuals, the case-control study is concerned with the frequency and amount of exposure in subjects with a specific disease (cases) and people without the disease (controls).
Why is a cohort study superior to a case-control study?
Cohort studies provide the best information about the causation of disease because you follow persons from exposure to the occurrence of the disease. With data from cohort studies you can calculate cumulative incidences. Cumulative incidences are the most direct measurement of the risk of developing disease.
What measure of association is used in a case-control study?
The odds ratio
The odds ratio is the “measure of association” for a case-control study. It quantifies the relationship between an exposure (such as eating a food or attending an event) and a disease in a case-control study.
What is not suitable in a cohort study?
Disadvantages of Prospective Cohort Studies They can be very expensive and time consuming. They are not good for rare diseases. They are not good for diseases with a long latency. Differential loss to follow up can introduce bias.
Why is it important to match case subjects and control subjects so closely in a case control study?
It is important to match case subjects and control subjects closely in a case control study because then they will have as differences as possible, which will limit the possible factors to getting a disease.
What are the advantages and disadvantages of case control vs cohort studies?
Advantages and disadvantages of cohort and case control studies
| Cohort studies | Case control studies | |
|---|---|---|
| Sample size | Large | Small |
| Cost | Elevated except if retrospective cohorts | Smaller |
| Time required | Long, sometimes very long except if retrospective cohorts | Shorter |
| Follow up | Difficult, loss to follow up | No follow up |
What measure of association is used in a cohort study?
The relative risk is the measure of association for a cohort study. It tells us how much more likely (or less likely) it is for people exposed to a factor to develop a disease compared to people not exposed to the factor.
Why cohort studies are an improvement over case-control studies with respect to measurement of exposure data?
Cohort study designs have several advantages over case-control studies in terms of exposure measurement. If exposure measurement occurs before disease occurrence, cohort studies are much less prone to differential measurement error.
What is measure Association?
A measure of association quantifies the relationship between exposure and disease among the two groups. Examples of measures of association include risk ratio (relative risk), rate ratio, odds ratio, and proportionate mortality ratio.
Why is relative risk not used in case-control studies?
In a case-control study there is no “follow-up” period. In a case-control study, you cannot measure incidence, because you start with diseased people and non-diseased people, so you cannot calculate relative risk. The case-control design is very efficient.
Does a cohort study need a control group?
Cohort studies differ from clinical trials in that no intervention, treatment, or exposure is administered to participants in a cohort design; and no control group is defined. Rather, cohort studies are largely about the life histories of segments of populations and the individual people who constitute these segments.
Why controls are needed in a case-control study?
A case-control study is designed to help determine if an exposure is associated with an outcome (i.e., disease or condition of interest). First, identify the cases (a group known to have the outcome) and the controls (a group known to be free of the outcome).
What is a case-control study?
This module focuses on case-control studies, which is one of the best known epidemiological study designs. Case-control studies are particularly useful when you don’t have the luxury of waiting for a long follow-up period to conclude.
What is the difference between case study and cohort study?
Case-control study designs are also retrospective and assess the history of the subject for the presence or absence of an exposure. COHORT STUDY The term “cohort” is derived from the Latin word cohors.
How do you choose a control group for a case study?
When designing a case-control study, the researcher must find an appropriate control group. Ideally, the case group (those with the outcome) and the control group (those without the outcome) will have almost the same characteristics, such as age, gender, overall health status, and other factors.
What are the inclusion and exclusion criteria in a case-control study?
In a case-control study, it is imperative that the investigator has explicitly defined inclusion and exclusion criteria prior to the selection of cases. For example, if the outcome is having a disease, specific diagnostic criteria, disease subtype, stage of disease, or degree of severity should be defined.