Chapter 1- Introduction

Question 1

Epidemiology

Answer 1

The study of the distribution and determinants of health related states or events in specified populations. This study is applied to control heath problems. Each person has certain characteristics that predispose them to or protect them against different diseases. Epidemiology is considered the cornerstone of public health

Question 2

Which factors interact to cause a person to develop a disease?

Answer 2

Genetics, environmental, behavioral and social factors

Question 3

Etiology

Answer 3

The cause of a disease. Does it transmit from person to person or from an animal to a person? Does it arise due to risk behaviors the person engages in?

Question 4

Objectives of epidemiology (5)

Answer 4

1. Determining etiology- this allows us to reduce morbidity and mortality from the disease, and determine how to prevent it
2. Determine the extent of disease in the community
3. Determine the natural history and prognosis of disease
4. Evaluate existing and newly developed preventative and therapeutic measures and modes of health care delivery- how have new measures impacted survival or quality of life?
5. Developing public policy relating to environmental problems, genetic issues, and other social and behavioral considerations regarding disease prevention and health promotion

Question 5

Extent of disease

Answer 5

The burden of disease in the community. We can use this information in order to plan health services and facilities, and to obtain sufficient health professionals.

Question 6

Natural history and prognosis of the disease

Answer 6

Some diseases are deadly or cause severe disability, other diseases are generally less serious. It is important to determine the natural history of a disease in order to develop methods of intervention, either through treatment or through other methods that prevent complications. The results from the new modalities can be compared to baseline to determine if the new modalities are actually working

Question 7

How do the patterns of community health problems change over time?

Answer 7

The diseases that most people are concerned about change over time. Cholera was a significant issue in the 19th century, but is unheard of in the US now. In 1900, infectious diseases made up the leading causes of death. In 2014, the leading causes of death were heart disease, cancer, chronic lower respiratory diseases, and unintentional injuries. The patterns of community health problems has transitioned to chronic issues that can’t be transmitted between people

Question 8

Epidemiologic transition

Answer 8

As countries become more industrialized, they begin to exhibit mortality patterns more consistent with those in developed countries- mortality from chronic diseases becomes a major challenge

Question 9

Why should be identify groups in the population who are at high risk for disease?

Answer 9

If we can identify high risk groups, we can direct preventative efforts, like screening programs, toward the populations that are most likely to benefit from them. Also, if we are aware of which groups are at risk, we may be able to identify the specific factors or characteristics that put them at high risk and then try to modify those factors. Some risk factors are modifiable, others are not

Question 10

Which risk factors are not modifiable?

Answer 10

Age, sex, and race

Question 11

Which risk factors are potentially modifiable?

Answer 11

Obesity, smoking, diet, sexual practices, and other lifestyle factors

Question 12

Primary prevention

Answer 12

An action taken to prevent the development of a disease in a person who is well and does not yet have the disease in question. For example, vaccination can ensure that a disease never develops. If a disease is associated with certain lifestyle factors, a person’s exposure to these lifestyle factors can be limited so they do not develop the disease. Primary prevention is the ultimate goal

Question 13

Secondary prevention

Answer 13

Involves identifying people where a disease process has already begun but who hasn’t yet developed clinical signs and symptoms of the illness. The objective of secondary prevention is to detect the disease earlier than it would have been detected in typical circumstances. This is often done through screening, which will generally catch the disease at a point where treatment will be easier or more effective (like mammograms to detect breast cancer at an earlier stage). Mortality and complications of the disease may be able to be prevented, and treatment can be less invasive and expensive

Question 14

Preclinical phase

Answer 14

The phase of an illness where the disease process has already begun but the person has not yet developed clinical signs and symptoms of the illness. Once a person develops signs or symptoms, they will generally seek medical advice

Question 15

Tertiary prevention

Answer 15

Preventing complications in those who have already developed signs and symptoms of an illness and have been diagnosed. This done through quick and appropriate treatment of the illness and through supportive measures such as physical therapy

Question 16

2 possible approaches to prevention

Answer 16

A population based approach and a high risk approach

Question 17

Population based approach

Answer 17

A preventative measure is widely applied to an entire population. For example, advice regarding diet or advice against smoking can be given to the entire population. These measures are considered public health measures

Question 18

High risk approach

Answer 18

A high risk group is targeted with a preventative measure. Screening for high cholesterol in children may be confined only to children from high risk families. These measures may require clinical action to identify which groups are high risk

Question 19

Epidemiology and clinical practice

Answer 19

Making a diagnosis often relies on population data in addition to the patient’s symptoms. Certain groups are more likely to be affected by certain diseases. Treatment is based which treatments have been effective for populations of people with the same disease. Determining a prognosis also relies on population data

Question 20

Steps of epidemiologic reasoning (2)

Answer 20

1. Determining whether an association exists between exposure to a factor or a characteristic of a person and the presence of a disease
2. Try to derive appropriate inferences about a possible causal relationship from the patterns of the associations that have been previously found

Question 21

Ignaz Semmelweis

Answer 21

An obstetrician who noticed that women in a maternity ward staffed by doctors were more likely to die from puerperal fever than women in a ward staffed by midwives. The reason for this was that the physicians and medical students in the first ward spent time performing autopsies on women who had died from puerperal fever, and then delivered babies from women on the maternity ward. Semmelweis suspected that pathogens were being transferred from the doctors to the women during vaginal examinations. Physicians and medical students where required to wash their hands after they finished autopsies and before they came into contact with patients, and the mortality rate decreased to the level of that observed in the second clinic

Question 22

Edward Jenner

Answer 22

In the 18th century, hundreds of thousands of people died from smallpox per year, and many people experienced complications. People were some given infectious material from smallpox patients (variolation), but these people sometimes died, developed other infections, or transmitted smallpox to others. Jenner observed that milkmaids were not affected by smallpox outbreaks. This is because milkmaids were exposed to cowpox, and milder form of smallpox. In 1796, Jenner performed the first vaccination by administering cowpox material to an 8 year old. He later exposed the 8 year old to smallpox, and he did not develop the disease

Question 23

John Snow

Answer 23

Snow believed, contrary to the miasmatic theory at that time, that cholera was transmitted through contaminated water. Snow collected data regarding the number of cholera cases in people who got their water from each water company in London. One water company had begun using a less polluted region of the Thames river as their water source, and the death rate from cholera in people who used this water was much lower

Question 24

When the frequency of a disease declines, who deserves the credit?

Answer 24

Over the past one hundred years, mortality rates from many common infectious diseases (diphtheria, pertussis, scarlet fever) have declined dramatically, The mortality rates decreased even before vaccines were developed and before more sophisticated treatments were available. This improvement is likely due to improvements in social conditions, safer water, and reduced exposure to pollutants. It is important to determine whether declines in mortality are due to medical interventions or other changes

Question 25

What does distribution mean in reference to epidemiology?

Answer 25

Patterns of occurrence by time, place, or person

Question 26

What does determinants mean in reference to epidemiology?

Answer 26

Causes and risk factors

Question 27

3 types of epidemiology

Answer 27

1. Descriptive
2. Analytic
3. Predictive

Question 28

Descriptive epidemiology

Answer 28

Understanding the distribution of determinants, health related events, and outcomes

Question 29

Analytic epidemiology

Answer 29

Study of determinants/factors as causes of health related events and outcomes

Question 30

Predictive epidemiology

Answer 30

Use of distributions to forecast outcomes, but not based solely on causes and effects

Question 31

What does health related states or events mean in reference to epidemiology?

Answer 31

Diseases, behaviors, exposures, etc.- anything that impacts the health or well being of the population

Question 32

How does epidemiological data inform public health practice?

Answer 32

Physicians often make recommendations or consider diagnoses based on epidemiological data. Studies that examine different cohorts of people can also be used to extrapolate to a specific patient and determine what their prognosis is likely to be