Table of ContentsView AllTable of ContentsDesignPurposeStrengthsWeaknesses
Table of ContentsView All
View All
Table of Contents
Design
Purpose
Strengths
Weaknesses
A cohort study often looks at 2 (or more) groups of people that have a different attribute (for example, some smoke and some don’t) to try to understand how the specific attribute affects an outcome. The goal is to understand the relationship between one group’s shared attribute (in this case, smoking) and its eventual outcome.
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Cohort Study Design
There are two categories of evidence-based human medical research:
Experimental research:This involves a controlled process through which each participant in aclinical trialis exposed to some type of intervention or situation—like a drug, vaccine, or environmental exposure. Sometimes there is also a control group that is not exposed for comparison. The results come from tracking the effects of the exposure or intervention over a set period of time.
Observational research:This is when there is no intervention. The researchers simply observe the participants' exposure and outcomes over a set period of time in an attempt to identify potential factors that could affect a variety of health conditions.
Cohort studies are longitudinal, meaning that they take place over a set period of time—frequently, years—with periodic check-ins with the participants to record information like their health status and health behaviors.
They can be either:
Purpose of Cohort Studies
Participants in cohort studies are grouped together based on having a shared characteristic—like being from the same geographic location, having the same occupation, or having a diagnosis of the same medical condition.
Each time the researchers check-in with participants in cohort trials, they’re able to measure their health behaviors and outcomes over a set period of time. For example, a study could involve two cohorts: one that smokes and the other that doesn’t. As the data is collected over time, the researchers would have a better idea of whether there appears to be a link between a behavior—in this case, smoking—and a particular outcome (like lung cancer, for example).
Strengths of Cohort Studies
Much of the medical profession’s current knowledge of disease risk factors comes from cohort studies. In addition to showing disease progression, cohort studies also help researchers calculate the incidence rate, cumulative incidence, relative risk, and hazard ratio of health conditions.
Retrospective cohort studies have their own benefits, namely that they can be conducted relatively quickly, easily, and cheaply than other types of research.
How Research Participants Are Protected
Weaknesses of Cohort Studies
While cohort studies are an essential part of medical research, they are not without their limitations.
These can include:
A Word From Verywell
Think about the last time you had a physical. Your healthcare provider likely measured several of your vital signs and gave you a blood test, then reported back to you about the various behaviors you may need to change in order to reduce your risk of developing certain diseases. Those risk factors aren’t just guesses; many of them are the result of cohort studies.
4 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Song JW, Chung KC.Observational studies: cohort and case-control studies.Plast Reconstr Surg. 2010;126(6):2234-2242. doi:10.1097/PRS.0b013e3181f44abc.Barrett D, Noble H.What are cohort studies?Evidence-Based Nursing. 2019;22(4):95-96. doi:10.1136/ebnurs-2019-103183Wang X, Kattan MW.Cohort studies: design, analysis, and reporting.CHEST. 2020;158(1):S72-S78. doi: 10.1016/j.chest.2020.03.014.Setia MS.Methodology series module 1: cohort studies.Indian J Dermatol. 2016;61(1):21-25. doi:10.4103/0019-5154.174011.
4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Song JW, Chung KC.Observational studies: cohort and case-control studies.Plast Reconstr Surg. 2010;126(6):2234-2242. doi:10.1097/PRS.0b013e3181f44abc.Barrett D, Noble H.What are cohort studies?Evidence-Based Nursing. 2019;22(4):95-96. doi:10.1136/ebnurs-2019-103183Wang X, Kattan MW.Cohort studies: design, analysis, and reporting.CHEST. 2020;158(1):S72-S78. doi: 10.1016/j.chest.2020.03.014.Setia MS.Methodology series module 1: cohort studies.Indian J Dermatol. 2016;61(1):21-25. doi:10.4103/0019-5154.174011.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Song JW, Chung KC.Observational studies: cohort and case-control studies.Plast Reconstr Surg. 2010;126(6):2234-2242. doi:10.1097/PRS.0b013e3181f44abc.Barrett D, Noble H.What are cohort studies?Evidence-Based Nursing. 2019;22(4):95-96. doi:10.1136/ebnurs-2019-103183Wang X, Kattan MW.Cohort studies: design, analysis, and reporting.CHEST. 2020;158(1):S72-S78. doi: 10.1016/j.chest.2020.03.014.Setia MS.Methodology series module 1: cohort studies.Indian J Dermatol. 2016;61(1):21-25. doi:10.4103/0019-5154.174011.
Song JW, Chung KC.Observational studies: cohort and case-control studies.Plast Reconstr Surg. 2010;126(6):2234-2242. doi:10.1097/PRS.0b013e3181f44abc.
Barrett D, Noble H.What are cohort studies?Evidence-Based Nursing. 2019;22(4):95-96. doi:10.1136/ebnurs-2019-103183
Wang X, Kattan MW.Cohort studies: design, analysis, and reporting.CHEST. 2020;158(1):S72-S78. doi: 10.1016/j.chest.2020.03.014.
Setia MS.Methodology series module 1: cohort studies.Indian J Dermatol. 2016;61(1):21-25. doi:10.4103/0019-5154.174011.
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