Descriptive Epidemiology Flashcards
Human health and disease are unequally distributed throughout populations.
True or false
True
What are the three Ws of descriptive epidemiology
Who is affected?
•Where did the event occur?
•When did the event occur?
Occurrence of a disease is classified according to which three variables in descriptive epidemiology
Define descriptive epidemiology study
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.”
Name three importance of descriptive epidemiology
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
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?
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.
What is a case report?
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
What is a case series
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)
What is a cross sectional study
- 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.
In cross sectional study, The presence or absence of disease and the presence or absence of the other variables are determined how?
are determined in each member of the study population or in a representative sample at one particular time.”
How is information inferred in descriptive epidemiology or how do epidemiologists think about data
State the difference between descriptive epidemiology and analytical epidemiology
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.
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
True
True
Name six person variables in descriptive epidemiology
Age
•Sex
•Marital Status
•Race and ethnicity
- Nativity and migration
- Religion
- Socioeconomic status
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
Age
True
The causes of morbidity and mortality differ according to stage of life
Name three causes in each age group
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.
Name four reasons for age association
Validity of diagnoses across the life span
•Latency effects
•Action of the “human biologic clock”
•Life cycle and behavioral phenomena
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?
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
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
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
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
True
Certain religions prescribe lifestyles that may influence rates of morbidity and mortality.
Explain how
- 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.
What is socioeconomic status
Name the three interrelated dimensions of socioeconomic status
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
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
True
People of lower social class usually get what kind of diseases
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.
Explain place variable in descriptive epidemiology
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
Explain international and national variations in rates of diseases
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.
Explain the rural or urban differences in disease rates
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.
Explain how localized places affect disease rates
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
State four time variables in descriptive epidemiology and state the two under clustering
- Secular time trends
- Cyclic fluctuations
- Point epidemics
- Clustering:
- Temporal
- Spatial
What are secular time trends and give an example
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.
What are cyclic trends or fluctuations and what are they related to
Give an example
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.
What is a point epidemic and give an example
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.
Define case clustering
What does clustering suggest
And give an example
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.
Explain the following terms Disease cluster Endemic disease Epidemic disease Pandemic disease Infection Infectious Infectious disease
What do epidemic disease depend on
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
Descriptive study design helps to quantify frequency of diseases true or false
True
What is the importance of descriptive epidemiology
It describes changes that occur overtime
Why is cross sectional called cross sectional
Define latency effect
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
