Descriptive Epidemiology

Question 1

Human health and disease are unequally distributed throughout populations.
True or false

Answer 1

True

Question 2

What are the three Ws of descriptive epidemiology

Answer 2

Who is affected?
•Where did the event occur?
•When did the event occur?

Question 3

Occurrence of a disease is classified according to which three variables in descriptive epidemiology

Define descriptive epidemiology study

Answer 3

Person
•Place
•Time

A descriptive epidemiologic study is one that is “. . . concerned with characterizing the amount and distribution of health and disease within a population.”

Question 4

Name three importance of descriptive epidemiology

Answer 4

Permits evaluation and comparison of trends in health and disease.

• Provides a basis for planning, provision, and evaluation of health services.
• Identifies problems to be studied using analytical methods (creation of hypotheses) a

Question 5

Name three types of descriptive epidemiology studies

Which study is the simplest?

Which study summarizes the characteristics of patients in clinical settings?
Which study surveys population to estimate the prevalence of a disease or exposure?

Answer 5

Case reports (counts)–simplest category.

• Case series–summarize characteristics of patients from major clinical settings.
• Cross-sectional studies–surveys of the population to estimate the prevalence of a disease or exposure.

Question 6

What is a case report?

Answer 6

are accounts of a single occurrence of a noteworthy health-related incident or small collection of such event

Done for a health event identified
The disease occurs before then later you find the patient and try to find out what happened
Example cosmetic surgery case report
Example:if sickle cell you give a profile of this case or when going for clinicals and you clerk a patient and report

Question 7

What is a case series

Answer 7

Case series is a larger collection of cases of disease, often grouped consecutively and listing common features such as the characteristics of affected patients.

Usually in a tabular form or graph form of similar cases(when events that occur are rare)
Example – Primary Amebic Meningoencephalitis (PAM)

Question 8

What is a cross sectional study

Answer 8

• Cross-sectional studies “. . . examine the relationship between diseases (or other health-related characteristics) and other variables of interest as they exist in a defined population at one particular time.
• Thus, a cross-sectional study is a type of prevalence study in which exposures and distributions of disease are determined at the same time, although it is not imperative for the study to include both exposure and disease.

Question 9

In cross sectional study, The presence or absence of disease and the presence or absence of the other variables are determined how?

Answer 9

are determined in each member of the study population or in a representative sample at one particular time.”

Question 10

How is information inferred in descriptive epidemiology or how do epidemiologists think about data

State the difference between descriptive epidemiology and analytical epidemiology

Answer 10

The process of inference in descriptive epidemiology refers to drawing conclusions about the nature of exposures and health outcomes and formulating hypotheses to be tested in analytic research

• Descriptive studies–used to identify a health problem that may exist. Characterize the amount and distribution of disease.
• Analytic studies–follow descriptive studies, and are used to identify the cause (determinants) of the health problem.

Question 11

Epidemiologists will make observations,use descriptive epidemiology study to make hypothesis,test the hypothesis made using analytical study and then make an inference from it true or false

I’m descriptive epidemiology you rule out chance,bias and confounding while in analytical epidemiology you control for chance,bias and confounding true or false

Answer 11

True

True

Question 12

Name six person variables in descriptive epidemiology

Answer 12

Age
•Sex
•Marital Status
•Race and ethnicity

• Nativity and migration
• Religion
• Socioeconomic status

Question 13

Which person variable is most important when describing the occurrence of a disease

Age-specific disease rates usually show greater variation

•As age increases, overall mortality increases as do the incidence of and mortality from many chronic diseases

True or false for both

Answer 13

Age

True

Question 14

The causes of morbidity and mortality differ according to stage of life
Name three causes in each age group

Answer 14

Childhood—developmental problems, e.g., congenital birth defects, infectious diseases such as meningococcal disease

• Teenage years—unplanned pregnancy, accidental injuries, violence, substance abuse
• Young Adults—accidental injury, homicide, suicide
• Older adults—chronic diseases (cardiovascular disease and cancers)
• ## Mothers who give birth when they are older have higher rates of diabetes than mothers who give birth at younger ages.

Question 15

Name four reasons for age association

Answer 15

Validity of diagnoses across the life span
•Latency effects
•Action of the “human biologic clock”
•Life cycle and behavioral phenomena

Question 16

All-cause age-specific mortality rates higher for male than for females from birth to 85yrs or older. And men often develop more severe forms of chronic diseases
What may it be due to?

Answer 16

May be due to social factors
•May have biological basis

•The question is the extent to which such differences will narrow as lifestyle, employment and health related behaviours equalize

Question 17

Categories
•Single or non-married (e.g., never married, divorced, widowed)
•Married
•Living with a partner

Of these groups,which tend to have lower rates of mortality and morbidity and which group are less likely to be overweight

Answer 17

In general, married people tend to have lower rates of morbidity and mortality.
•Examples: chronic and infectious diseases, suicides, and accidents.

•Never married adults (especially men) less likely to be overweight

Question 18

Marriage may operate as a protective or selective factor.

•Protective: may provide an environment conducive to health.

•Selective: People who marry may be healthier to begin with.
True or false

Answer 18

True

Question 19

Certain religions prescribe lifestyles that may influence rates of morbidity and mortality.
Explain how

Answer 19

• Example: Seventh Day Adventists
• Follow vegetarian diet and abstain from alcohol and tobacco use.
• Have lower rates of CHD, reduced cancer risk, and lower blood pressure.
• Similar findings for Mormons.

Question 20

What is socioeconomic status

Name the three interrelated dimensions of socioeconomic status

Answer 20

Socioeconomic status (SES) is defined as a “descriptive term for a person’s position in society, . . .”
•SES is often formulated as a composite measure of three interrelated dimensions:
•Income level,
•Education level, and
•Type of occupation
•Three-factor measure would classify persons with high SES as those at the upper levels of income, education, and employment status

Question 21

The social class gradient (variability in SES from high to low and vice versa) is strongly and inversely associated with levels of morbidity and mortality.
•Low social class is related to excess mortality, morbidity, and disability rates.
•Factors include:
•Poor housing
•Crowded conditions
•Racial disadvantage
•Low income
•Poor education
•Unemployment

True or false

Answer 21

True

Question 22

People of lower social class usually get what kind of diseases

Answer 22

Higher rate of infectious disease.
•Higher infant mortality rate and overall mortality rates.
•Lower life expectancy.
•Larger proportion of cancers with poor prognosis.
•May be due to delay in seeking health care.

Question 23

Explain place variable in descriptive epidemiology

Answer 23

Morbidity and mortality vary greatly with respect to place (geographic regions that are being compared).
•Types of place comparisons:
•International
•Geographic (within-country) variations
•Urban/rural differences
•Localized occurrence of disease

Question 24

Explain international and national variations in rates of diseases

Answer 24

RATES OF DISEASE
•World Health Organization (WHO) tracks international variations in rates of disease.
•Infectious and chronic diseases show great variation across countries.
•Variations are attributable to climate, cultural factors, dietary habits, and health care access.
•Such variations are reflected in great international differences in life expectancy.
•CIA report for 223 countries and indicated that the world life expectancy was 66.1 years (2008 estimate).
•The three countries with the highest life expectancy in 2008 were Andorra (83.5 years), Macau— technically not a country—(83.3 years), and Japan (82.1 years)

NATIONAL (WITHIN-COUNTRY) VARIATIONS IN RATES OF DISEASE

• Many countries, especially large ones, demonstrate within country variations in disease frequency
• Regional variations within country due to differences in;
• Climate
• Geology
• Latitude
• Pollution, and
• Ethnic/racial concentrations.

Question 25

Explain the rural or urban differences in disease rates

Answer 25

Urban and rural show variations in morbidity and mortality related to environmental and lifestyle issues

• Urban diseases and causes of mortality are more likely to be those spread by person-to-person contact, crowding, and inner-city poverty or associated with urban pollution
• Example: lead poisoning in inner cities

•Agriculture is a major category of employment for the residents of rural areas. Farm workers often are exposed to hazards such as toxic pesticides and unintentional injuries caused by farm equipment.

Question 26

Explain how localized places affect disease rates

Answer 26

Disease patterns are due to unique environmental or social conditions found in particular area of interest.
•Examples include:
•Fluorosis: associated with naturally occurring fluoride deposits in water.
•Lung cancer associated with radon gas found in some geographic areas

• Local environmental conditions also may support disease vectors that may not survive in other areas
• Dengue fever, a viral disease transmitted by a species of mosquito (a vector) that is present along the border that separates Texas from Mexico near the Gulf of Mexico

Question 27

State four time variables in descriptive epidemiology and state the two under clustering

Answer 27

• Secular time trends
• Cyclic fluctuations
• Point epidemics
• Clustering:
• Temporal
• Spatial

Question 28

What are secular time trends and give an example

Answer 28

Secular trends refer to gradual changes in the frequency of a disease over long time periods.
Secular trends either go up or come down over time
•Example is the decline of heart disease mortality in the U.S.
•May reflect impact of public health programs, dietary improvements, better treatment, or unknown factors.

Question 29

What are cyclic trends or fluctuations and what are they related to
Give an example

Answer 29

Cyclic trends are increases and decreases in the frequency of a disease or other phenomenon over a period of several years or within a year.
•Related to changes in lifestyle of the host, seasonal climatic changes, and virulence of the infectious agent.
Cyclic trends goes up and comes down and goes up and comes down overtime according to a cycle
Examples:
•Higher heart disease mortality in winter; more accidents in summer; seasonal variation in incidence of meningococcal disease.
•Mortality from pneumonia and influenza peaks during February, decreases during March and April, and reaches its lowest level during the early summer.

Question 30

What is a point epidemic and give an example

Answer 30

point epidemic indicates the response of a group of people circumscribed in place and time to a common source of infection, contamination, or other etiologic factor to which they were exposed almost simultaneously.

Point epidemic simultaneously exposed a group of people to a certain condition
Examples:
•foodborne illness; responses to toxic substances; infectious diseases.

Question 31

Define case clustering
What does clustering suggest
And give an example

Answer 31

Case clustering–refers to an unusual aggregation of health events grouped together in space and time.
•Clustering may suggest common exposure of the population to an environmental hazard.
•It may also be purely spurious—due to the operation of chance

• Temporal clustering: health events that are related in time e.g., post-vaccination reactions, postpartum depression.
• Spatial clustering: concentration of disease in a specific geographic area, e.g., Hodgkin’s disease.

Question 32

Explain the following terms
Disease cluster
Endemic disease
Epidemic disease 
Pandemic disease
Infection
Infectious
Infectious disease

What do epidemic disease depend on

Answer 32

Disease cluster:
•Disease cluster is an aggregation of events or disease in space and/or time in amounts that are believed or perceived to be greater than could be expected by chance
•That is the occurrence of high cases of disease in close proximity by geography or time or both

• Endemic disease
• Disease that is habitually present within a geographic area . Eg malaria in sub-Saharan Africa or in Ghana etc

•Epidemic disease
•The occurrence of a disease clearly in excess of what is normally expected or present in a community or region eg cholera outbreaks
This depends on the type of disease or the size of the population

Pandemic:A worldwide or global epidemic eg H1N1 (swine flu) pandemic in 2009 causing about 17,000 deaths globally)
•Ebola in 2014

Infection - The invasion of a susceptible host by an infectious agent. Usually implies a relationship where the agent’s benefit comes at the expense of the host
•
Infectious - Usually refers to an infected host who is capable of transmitting infection to other susceptible hosts
•
Infectious Disease - A set of physical and clinical symptoms present in an infected host. These symptoms can result from direct pathology caused by the agent, or by damage incurred by the host’s own immune response

Question 33

Descriptive study design helps to quantify frequency of diseases true or false

Answer 33

True

Question 34

What is the importance of descriptive epidemiology

Answer 34

It describes changes that occur overtime

Question 35

Why is cross sectional called cross sectional

Define latency effect

Answer 35

Cuz not everyone or every case is included
It’s random sampling

Disease + possible exposure or causes

Information is gotten about both disease and exposure at the same time

Latency effect : you do something at a young age and you see the disease or see the effect when you grow