SPHL100 - Quiz I: Epidemiology & Rates

SPHL100 with Shuling Wu

Epidemiology

The study of the distribution and determinants of health-related states among specified populations and the application of that study to the control of health problems; Epidemiologists are disease detectives!

John Snow

Father of modern epidemiology; famous for investigation of the cholera outbreak in 1854 in Soho District of London. Discovered the breakout to be from street water pump while safe spots were from private wells and heated water.

Epidemiology study types: Experimental vs Observational

What are the two observational study types?

Analytic and Descriptive

Analytic Epidemiology

Test hypotheses and determine causality/risk factors

How was the population affected?

Why was the population affected?

Explains patterns; determines causes/associations

Descriptive Epidemiology

Characterize and summarize a public health event

When was the population affected (time)?

Where was the population affected (place)?

Who was affected (person)?

Identifies patterns; generates hypotheses

What is unique about epidemiological studies?

Observational science; hypothesis driven and collect empirical data to access risk factors and disease distribution across populations.

Concerned with groups of people and population health unlike clinical medicine.

What are the four epidemiology purposes?

D.D.I.E

1. Discover the agent, host, and environmental factors that affect health.

2. Determine the relative importance of causes of illness, disability, and death.

3. Identify those segments of the population that have the greatest risk from specific causes of ill health.

4. Evaluate the effectiveness of health programs and services in improving population health. This information helps inform public health policy and planning

How does public health use epidemiological information?

They use it to make policies and programs designed to decrease spread and severity of disease. 

Use tracked disease rates to enforce/relax prevention measures.

Epidemiological data, combined with biostatistics, forms the empirical evidence necessary to establish causal inference in research

What kind of data is primarily used in the field of epidemiology? (Quantitative or Qualitative information?)

Quantitative!

However, the field recognizes the value of qualitative information and insight. Furthermore, some experts argue that all data systems need guidance from "thick data," which refers to precious unquantifiable insights from actual people, to help make meaning of quantitative data

What does a QALY measure?

QALYs assess whether an intervention will increase life years with high quality. It is focused on estimating high-quality years added by an intervention

What does a DALY measure?

DALYs calculate the amount of a person's life that is lived with high quality, effectively subtracting years lost due to disability, illness, or premature death

What do we do with this information? What does public health seek to improve QALY or DALY?

QALYs and DALYs allow public health officials to make comparisons regarding health status and outcomes between different nations, states, circumstances, or health systems.

Public health aims to maximize both the quality and quantity of life; therefore, the goal is to increase QALYs and minimize DALYs.

What is specificity?

The likelihood that if an individual does not have the disease, the results of the test will be negative. It is also known as the true negative rate.

What is sensitivity?

The likelihood that if an individual actually has the disease, the test will come back positive. It is also known as the true positive rate.

What is the difference between Specificity vs Sensitivity?

Sensitivity measures the ability of a test to correctly identify individuals who are sick (true positives)

Specificity measures the ability of a test to correctly identify individuals who are healthy (true negatives)

How does public health use this information?

Sensitivity and specificity are used by public health when conducting screening procedures, which are a critical component of public health aimed at identifying cases of disease very early.

What is the difference between a Type I and Type II error? (What is a false positive and false negative?)

Statistically, Type I error is considered the worst mistake and must be minimized

What is the difference between prevalence rates and incidence rates?

Prevalence is the proportion of a population that is affected by the problem at a given point in time, counting both existing and new cases. It reflects the total disease burden

Incidence is the proportion of a population that develops new cases of the disease over a given period of time. It talks about the number of new cases

How do you calculate prevalence rates?

Expressed as a percentage

How does public health use this information (Prevalence)?

Prevalence provides a snapshot of the population's health at a specific time. It is primarily useful for:

• Estimating the burden of disease

• Planning health services, such as ensuring adequate hospital beds, doctors, and nurses are available to care for the total number of people who are ill

Prevalence is not useful for identifying risk factors because it measures all cases, not just new ones

How do you calculate incidence rates?

The population at risk is generally defined as the Total Population minus Existing Cases

How does public health use this information (Incidence)?

Incidence rates are crucial for determining whether a public health problem is getting worse or better. If the number of new cases is increasing daily, the disease is worsening. This information is used to:

• Identify potential risk factors because it measures the appearance of new cases

• Evaluate the effectiveness of interventions; if new cases continue to rise, the current intervention is likely not working

C.R.A.P. Test

Assess if the article is Current, Relevant, has Authority, is Accurate, and what its Purpose is

What is the difference between Misinformation vs Disinformation?

Misinformation: false or inaccurate information that is spread unintentionally

Disinformation: false information that is created and spread intentionally to mislead, manipulate, or cause harm

What are examples of a reliable source? What things do you look for?

Examples of reliable sources often include most government data (due to internal checks and balances) and established news sources or research journals that actively work to minimize bias and adhere to journalistic standards

Sensitivity/Specificity (The Diagnostic Test)

The physician first uses a diagnostic test.

Sensitivity is how likely the test is to correctly identify the infection if it is truly present.

Specificity is how likely the test is to correctly give a negative result if the patient is truly healthy. You need both to trust the diagnosis.

QALY/DALY (The Treatment Goal)

Once the infection is confirmed, the physician chooses a treatment.

QALY (Quality Adjusted Life Years) measures the anticipated high-quality years that the chosen treatment will add to the patient's life.

DALY (Disability Adjusted Life Years) measures the anticipated years of quality life lost due to the infection or lingering disability if the treatment is ineffective or delayed. The goal is to maximize QALYs and minimize DALYs.