46. EBM - Intro to Epidemiology

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Questions and Answers

What must occur for causation to be established in epidemiology?

The cause must be more severe than the effect.

The effect must precede the cause.

The cause must precede the effect. (correct)

The effect must be reversible.

Which criterion suggests that increased exposure to a factor should correlate with a higher incidence of the disease?

Biological gradient (correct)

Plausibility

Temporality

Analogy

How does coherence in epidemiological research influence the understanding of a disease's effect?

By indicating that all cases must be reported.

By confirming that the disease has historical precedence.

By ensuring that laboratory findings align with epidemiological evidence. (correct)

By providing absolute evidence of causation.

What characterizes a pandemic as opposed to an epidemic?

It affects a wider geographical area and infects more people. Signup and view all the answers

Which of the following best describes an outbreak in epidemiological terms?

An unexpected surge in disease cases in a community. Signup and view all the answers

What is the primary difference between endemic and epidemic diseases?

Endemic diseases are always present in a population, while epidemics occur suddenly. Signup and view all the answers

Which term describes a disease spread across multiple regions impacting a widespread population?

Pandemic Signup and view all the answers

Which of the following statements about clusters in epidemiology is true?

A cluster represents a group of cases that may exceed what is expected in a specific time and place. Signup and view all the answers

Which of the following best defines epidemiology?

The study of the distribution and determinants of health-related states among populations. Signup and view all the answers

What does the term 'distribution' in epidemiology refer to?

The frequency and pattern of health outcomes in specified populations. Signup and view all the answers

Which of the following criteria is NOT part of the Bradford Hill Criteria of Causation?

Randomness Signup and view all the answers

In epidemiology, how is a 'pandemic' best described?

An epidemic that has spread across a larger geographic area, often worldwide. Signup and view all the answers

What is the primary goal of calculating prevalence in epidemiology?

To evaluate the total number of existing cases of a disease at a specific point in time. Signup and view all the answers

Which of the following populations would be most relevant for an epidemiological study?

A group of individuals within the same geographic region. Signup and view all the answers

The term 'cluster' in epidemiology refers to what?

A collection of cases of a disease occurring within a defined geographical area and time period. Signup and view all the answers

What is the importance of identifying segments of the population with the greatest risk in epidemiology?

To inform public health interventions and resource allocation. Signup and view all the answers

What is the primary distinction between incidence risk and incidence rate?

Incidence risk is a proportion, while incidence rate accounts for the follow-up period and population dynamics. Signup and view all the answers

Which factor is NOT essential for calculating a disease rate?

The size of the health care facility Signup and view all the answers

What does a higher incidence rate typically indicate about a population?

An increased speed of new disease cases occurring within that population. Signup and view all the answers

In a cohort study, which situation could potentially distort the incidence risk calculation?

Participants enter the study at different start times. Signup and view all the answers

Why is it important to follow participants over time in a study calculating incidence rates?

To ensure the complete capture of all disease cases. Signup and view all the answers

How does the concept of 'person-time' contribute to the calculation of incidence rates?

It allows for a dynamic view of disease occurrence in a changing population. Signup and view all the answers

Which of the following is considered a discrete outcome in epidemiology?

Incidence of new diabetes cases Signup and view all the answers

What is the main purpose of measuring incidence in public health?

To identify trends in disease transmission and inform health interventions. Signup and view all the answers

What equation accurately represents the calculation of prevalence?

Number of People with Disease / Number of People in the Population x 100 % Signup and view all the answers

Which statement is true regarding point prevalence?

It indicates the proportion of cases at one specific point in time. Signup and view all the answers

If a disease's prevalence increases significantly, which of the following explanations is NOT likely?

A decrease in the rate of new cases being diagnosed. Signup and view all the answers

What is the main distinction between prevalence and incidence?

Prevalence measures disease burden at a point in time while incidence measures new cases over a period. Signup and view all the answers

Given the prevalence of COPD in 2018 at a practice with 39,640 patients, what was the prevalence percentage?

4.7% Signup and view all the answers

Which of the following could lead to a decrease in disease prevalence?

Increased recovery rates of existing cases. Signup and view all the answers

In the example of COPD, what is the incidence calculated from July 1st to August 1st given a rise in cases during the month?

10.6% Signup and view all the answers

What does a low period prevalence suggest about a disease in a population?

More treatments leading to recovery are available. Signup and view all the answers

What does the prevalence of COPD in 2018 represent as a percentage of the total population?

4.5% Signup and view all the answers

How many new cases of COPD were diagnosed in 2019 compared to 2018?

46 Signup and view all the answers

What is the incidence rate of new COPD cases in 2019 per 1000 population?

1.15 per 1000 Signup and view all the answers

What is the primary concern if the number of patients remained static while new COPD cases rose significantly?

The emergence of new risk factors such as excessive smoking Signup and view all the answers

What does prevalence-incidence bias imply when studying a specific health outcome?

It may exclude patients with severe or mild forms of the disease. Signup and view all the answers

Which year saw a higher prevalence of COPD among patients?

2019 Signup and view all the answers

Why might a GP feel reassured after reviewing the prevalence and incidence data over the two years?

The number of new cases was proportional to the increase in patient numbers. Signup and view all the answers

What could be a potential outcome of not considering prevalence-incidence bias during data collection?

An inaccurate estimation of exposure and outcome association Signup and view all the answers

Study Notes

Epidemiology

The study of the distribution and determinants of health-related states among specified populations.
Application of this study to controlling health problems.
Methodology used to find the causes of health outcomes and diseases in populations.
In epidemiology, the patient is the community, and individuals are viewed collectively.

Key Terms in Epidemiology

Epidemic: A disease occurrence among a population exceeding what is expected in a given time and place.
- Example: Ebola in parts of Africa
Pandemic: A disease or condition that spreads across regions.
- Example: COVID-19
Endemic: Disease or condition present among a population at all times.
- Example: Malaria in Africa
Cluster: A group of cases in a specific time and place that might be more than expected.
- Example: Measles outbreak at a factory in Fort Worth, Texas.
Rate: The number of cases occurring during a specified period.
- Always dependent on the size of the population during that period.

Outcomes in Epidemiology

Discrete: Disease occurrence or severity.
Continuous: Blood pressure or glucose levels

Rates in Epidemiology

Rates are used to compare health problems among different populations that include two or more groups who differ by a selected characteristic.

Incidence

The occurrence of NEW cases of disease or injury in a population over a specified period of time.
Used to describe how quickly the disease is occurring in a population.
Used to identify increasing transmission and influence decision making about public health interventions.
Can be presented as a proportion (risk) or a rate (person-time).

Prevalence

The proportion of people with a particular disease at a particular timepoint.
Point prevalence is calculated by dividing the number of cases at one time by the total population at the same point in time.
Period prevalence is the proportion of people with a particular disease during a given time period.

Prevalence and Incidence Examples

50 people are followed for one month to see how many have or develop COVID.
- The prevalence of this disease is 8 per 50, or 0.16, or 16%.
- The incidence from July 1st to August 1st is 5 per 47, or 0.106, or 10.6%.

Prevalence vs. Incidence

Prevalence includes all cases (new and preexisting cases) in the population, while incidence only considers new cases.

Factors that Affect Incidence & Prevalence

Prevalence-Incidence Bias: A type of selection bias (Neyman bias) that occurs when individuals with severe or mild disease are excluded.
- This can lead to errors in the estimated association between an exposure and an outcome.
- Example: A study on cardiac arrest only collecting data on arrival to the emergency department, missing cases declared dead on scene.

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Description

Test your knowledge on the fundamental concepts of epidemiology, including key terms like epidemic, pandemic, and endemic. This quiz will help you understand the distribution and determinants of health-related states among populations and the methodologies used in epidemiological studies.