Epidemiology

Question 1

What is epidemiology?

Answer 1

The study of health and disease in populations.

The study of the distribution and determinants of disease frequency in human populations.

It gives us tools for counting.

Question 2

Why does studying the population matter?

Answer 2

The population behaves differently from the individual.
There are insights that you can get from the population that you would miss from the individual.

Question 3

What are some of the subfields of Epi?

Answer 3

• Chronic disease
• Infectious diseases
• Social epi
• environmental epi
• nutritional epi
• aging
• CVD
• epi methods

Question 4

What makes epi different from other health disciplines?

Answer 4

• The only field concerned with the occurrence of a disease in human populations and how it changes over time.
• Role is to develop and apply methods for assessing health and disease.

Question 5

5 objectives of epi

Answer 5

1) Identify the cause of the disease and its risk factors
2) Determine the extent of the disease in a community
3) Study the natural history and progression of the disease
4) Evaluate the preventative and therapeutic measures
5) Provide a foundation for developing policy

Question 6

What is the epi toolkit (there are 7)?

Answer 6

• Asking questions
• Study design
• Measurement
• Statistical analysis
• prevention
• surveillance
• outbreak investigation

Question 7

What are the elements of a good question in epi?

Answer 7

Clearly define:
- study sample (e.g., US adults)
- exposure of interest e.g., COVID)
- outcome of interest e.g., fatigue, brain fog, cardiovascular problems)

time period (e.g., 1-3 year period)

Question 8

What are the things you have to measure and how do you go about it in epi?

Answer 8

Enumerate population
- there are many obstacles
- who is making the decisions on the categories and how to get the data (personal biases)

Measure exposure
- factor that may be associated with outcome
- clear difference between exposed and unexposed
- clear, objective, and measurable
- collect data from: surveys, medical records, lab studies, environmental data, disease registries
- e.g., smokers vs non-smokers

Measurement of outcomes
- clear, objective, and measurable
- come from similar sources
- e.g., number of times reported having COVID

Question 9

What are the major epi study designs?

Answer 9

• Randomized control trial (RCT) –> Gold standard
• Cohort studies
• Case-control study
• Cross-sectional study

Question 10

What are RCTs, and when are they used?

Answer 10

• cause -cause-and-effect relationship
• disease-free at the start –> either placebo pr treatment group
  used to:
• test new medical devices or treatments
• evaluate new methods and approaches in healthcare delivery
• test new potential social interventions
• costly
• ethical considerations

Question 11

What are prospective cohort studies and when are they used?

Answer 11

• observational studies
• Same as RCT but from an observational POV
• Answers question: what are the effects of a particular exposure or intervention
• Starts with exposed/unexposed
• Everyone is disease-free
• Longitudinal follow
• Measures health outcomes
• costly
• time intensive

Question 12

What is a case-control study and when are they used?

Answer 12

• observational study
• start with diseased (cases) or not diseased (control)
• Good for studying rare outcomes
• look back to see exposure history
• subject to recall bias
• can’t look at incidence

Question 13

What are cross-sectional studies, and when are they used?

Answer 13

• observational studies
• analyze data at a single point in time to assess associations
• great to generate new hypotheses
• low cost
• can’t establish temporality
  -not useful for rare diseases

Question 14

What is a bias, and what are some of the types of bias you might encounter in an investigation?

Answer 14

Bias –> systematic error in a study, which leads to an incorrect estimate of the association between the exposure and the disease

Selection bias –> who is in the study population

Recall bias –> can you accurately remember your exposure?

Question 15

What is confounding?

Answer 15

a distortion in the association between the exposure and the outcome caused by a third variable associated with both. It can cause you to over or underestimate the association

Question 16

What is the difference between incidence and prevalence?

Answer 16

Incidence - new cases in the population, is associated with time
Prevalence - existing cases in the population (total number of cases)

Question 17

What are the methods of statistical analysis used in epi?

Answer 17

• Odds ratio
• incidence/ prevalence

Question 18

What are the three levels of PH prevention?

Answer 18

• Primary –> stop disease before it starts
• Secondary –> catch early disease or risk factors
• Tertiary –> manage disease and prevent complications

prevention is where epi methods translate into PH practice

Question 19

What is surveillance?

Answer 19

PH surveillance is the ongoing, systematic collection, analysis, and interpretation of data essential to planning, implementation, and evaluation of PH practice

Question 20

What is the difference between endemic, epidemic and pandemic? What is the role that surveillance plays in identifying this?

Answer 20

Endemic - natural occurrence of a disease in a given geographic area and time period

Epidemic - abnormal increases in the occurrence of an infectious disease

Pandemic - global epidemic affecting exceptionally high proportions of the global population

Surveillance identifies this spikes in incidences to catch the epidemics and contain them

Question 21

What is outbreak investigation, and when is it implemented?

Answer 21

• outbreak established through surveillance –> outbreak investigation
• respond to outbreaks by going to help and collecting data