Cohort Studies and Epidemiology

Flashcards for review of key concepts in cohort studies and epidemiology.

What is a cohort study?

A cohort study is an observational study that follows a defined group of people prospectively to assess the occurrence of disease following exposure.

What is the primary purpose of cohort studies?

Cohort studies aim to understand disease causation and prevention.

What are the two main types of study designs?

Observational studies and intervention studies.

What is an observational study?

An observational study is where the investigator observes, measures, and records data without intervening in the participants' routine.

What is an intervention study?

An intervention study involves the investigator actively introducing a treatment or intervention and measuring the outcomes.

Define ‘exposure’ in epidemiological studies.

An exposure is a risk or protective factor being studied for its association with disease.

What type of studies assess both exposure and disease status at one point in time?

Cross-sectional studies.

What method can be used to identify the association between exposure and disease?

Analytic epidemiology helps determine if exposure and disease are linked.

What are confounding factors?

Confounding factors are variables that may distort the relationship between an exposure and an outcome in observational studies.

What does the term 'cumulative incidence' refer to?

Cumulative incidence refers to the number of new cases of a disease in a defined time period divided by the number in the study population at the start.

What is the significance of a Randomized Controlled Trial (RCT)?

RCTs minimize confounding by randomizing participants to treatment groups, ensuring similar characteristics at baseline.

What type of study can provide stronger evidence for causality?

Cohort studies provide stronger evidence for causality compared to cross-sectional or case-control studies.

Why are cohort studies beneficial for studying rare exposures?

Cohort studies can focus on specific populations selected based on exposure, making it easier to observe rare exposures.

What is the downside of cohort studies regarding sample size?

Cohort studies often require large numbers of participants to achieve statistically significant results.

How is exposure measured in a study?

Exposure can be measured through questionnaires, medical records, or biological assessments.

What is ‘reverse-causality’?

Reverse-causality occurs when the presumed outcome affects the exposure rather than the other way around, often seen in cross-sectional studies.

What factors can affect the generalizability of cohort study results?

Cohort characteristics and the specific population from which the sample was drawn can impact generalizability.

How can the effects of confounding be reduced?

By stratifying analyses or using multivariable statistical models to adjust for confounding variables.

What is a Poisson regression used for in cohort studies?

Poisson regression is used to provide adjusted risk ratios or rate ratios in observational studies.

What is the difference between risk ratio and rate ratio?

Risk ratio compares the risk in exposed vs unexposed, while rate ratio compares incidence rates in exposed vs unexposed.

List one advantage of using cohort studies over case-control studies.

Cohort studies can measure exposures before the onset of disease, providing clarity on causal relationships.

What impact does loss to follow-up have on cohort studies?

Loss to follow-up can introduce bias and affect the validity of the study results.

What defines a 'healthy cohort' in a cohort study?

A healthy cohort consists of individuals who do not have the disease being studied at the start of the study.

Name one major cohort study example.

The Adventist Health Study is a notable example of a cohort study.