Study Guide Questions Exam 1 Flashcards
Definition of epidemiology
The study of the occurrence and distribution of health-related events, states, and processes in specified populations, including the study of the determinants influencing such processes and the application of this knowledge to control of relevant health problems
Definition of count
Refers to the number of cases of a disease or other health phenomenon being studied.
Definition of ratio
The value obtained by dividing one quantity by another. Rates and proportions are ratios.
Definition of proportion
A type of ratio in which the numerator is part of the denominator.
Rate definition
A type of ratio where the denominator involves a measure of time. The numerator consists of the frequency of a disease over a specified period, and the denominator is a unit size of the population.
Why are prevalence studies useful?
They describe the health burden of a population and in allocation of health resources.
Can be used by epidemiologists to estimate the frequency of an exposure in a population.
Population at risk definition
Those members of a population who are at risk for contracting a specific disease or adverse health outcome.
How does prevalence usually get reduced?
Death or cure
What can increase the prevalence?
New cases, or incidence
Prolongation of life with treatment, which does not completely cure the disease.
What are the two main branches of epidemiology?
Descriptive and analytic
Descriptive epidemiology definition
The study of the distribution of health states in populations by characteristics of person, place, and time.
What is the main purpose of descriptive epiemiology?
Looks for patterns between groups of people, over time or across geographical areas.
What is the main concern of analytic epidemiology?
The study of determinants
Definition of analytic epidemiology
The multi-disciplinary study of the determinants of health states in populations, on all levels from the molecular to the entire ecosystem, and including both the biological sphere and the broader social environment.
What are the four main purposes of epidemiology?
- Public health assessment
- Evaluating a health program, policy, or clinical service.
- Finding causes of a disease.
- Completing the clinical picture of a dz
Definition of duration
The average length of time that people are ill with a dz
Begins at illness and ends at recovery or death
Limitations of counts
Gives very limited information
You cannot compare two populations using counts.
What can decrease the prevalence?
Decreased incidence
Improved cure rate
Increased death rate
What increases incidence?
Increased risk
What decreases incidence?
Decreased risk
How is incidence useful?
Helps in research of etiology/causality of dz
Estimates the risk of developing a dz
Used to estimate the effects of exposure to a hypothesized factor of interest
How are prevalence and incidence related to each other?
Prevalence = incidence x duration
Definition of crude rates
Summary rates based on the actual number of events in a population over a given time period.
Specific rates definition
A type of rate based on a particular subgroup of population defined, for example, in terms of race, age, or sex, or they may refer to the entire population but be specific for some single cause of death or illness.
Cause-specific rate definition
A rate that specifies events, such as deaths according to their cause.
What is a disadvantage of specific rates?
The difficulty of visualizing the big picture of these situations.
Definition of adjusted rates
Summary measures of the rate of morbidity or mortality in a population in which statistical procedures have been applied to remove the effect of differences in composition of the various populations.
Direct method definition
A rate adjustment that applies specific rates for a group to a standard population.
When would a direct method be used?
If age-specific death rates in a population to be standardized are known and a suitable standard population is available.
What are the requirements for direct adjustment?
The application of the observed rates of dz in a pop to some standard pop to derive an expected # (rate) of mortality.
When is the indirect method used?
If age-specific death rates of the population for standardization are unknown or unstable
What does a demographic transition involve?
The movement of all human populations form experiencing high death and birth rates to experiencing very much lower death and birth rates.
What are the steps in demographic transition?
Population increases in size
Move from being predominantly rural to being predominantly urban
Move from having young age structures to having old age structures.
When in the demographic transition does the epidemiologic transition occur?
In stage two, when infectious diseases decline.
What occurs after the epidemiologic transition?
The fertility transition
What caused the decline in infectious disease mortality?
The industrial revolution in the late 19th and early 20th centuries raised the living standards of most people with improvements in: -Nutrition -Housing conditions -Sanitation -Water supply The rise in living conditions was then followed by another change in the mid-20th century: -Abx -Immunization programs
What also occurred in the 18th-19th centuries that also caused an epidemiologic transition?
Systems of administration, transport, and trade led to a decrease in famine.
Quarantining of ships to prevent disease spread
Smallpox vaccination
Rising living standards
Nutritional improvements
Cleaner water supplies
Sanitation system
Discovery of germ theory of disease
Use of antiseptic procedures in hospitals
Discovery of the role of mosquitos in malaria transmission
Establishment of health departments
Causes of the epidemiologic transition: developing countries in the 20th century
Abx DDT to control mosquitos Vaccination against childhood diseases Oral rehydration Improved latrines Rise of the WHO Improvements in water and sewage Rising living standards Mass education Secularization of attitudes toward health and medicine
Why do fertility rates change in stage 3?
Consequence of the epidemiologic transition. After death rates go down, people start to have fewer children, since nearly all will survive to grow up, but not all can be easily supported.
What is a consequence of the fertility transition?
Populations become older.
Fewer young people are born.
Lower mortality and longer life expectancy also contribute to population aging but not as much as low fertility
Far reaching consequences of chronic, non-infectious, non-communicable diseases being very prevalent
Chronic non-communicable conditions can lead to severe or immediate disabilities: -Hip fx -Stroke And/or slow progressive disability: -Arthritis -DM
What is globalization?
Changes in the nature of human interaction across a wide range of spheres, including the economic, political, social, technological and environmental, in which boundaries of various kinds are being eroded.
Emerging infectious dzs
HIV/AIDS SARS Ebola Sin nombre hantavirus Lassa fever Legionnaire's dz Mad cow dz COVID-19
Re-emerging infectious dzs
Avian influenza TB West Nile virus Dengue fever Malaria MRS E. coli Cholera Drug-resistant gonorrhea
Reasons for emerging and re-emerging infectious dzs
Microbial adaptation and change Human susceptibility to infection Poverty and social inequality International travel and commerce Bioterrorism-related dzs Changing ecosystems caused by: -Climate change -Deforestation -Population growth -The disruption of habitats containing new viruses
Examples of abx resistance
MRSA
Re-emergence of TB due to development of strains resistant to abx
Infectious dzs the homeless are more likely to get
20-40 x the prevalence of TB compared to the gen pop HIV MRSA Hep C Hep B Scabies Body lice
Category A bioterrorism agents
Anthrax Botulism Plague Smallpox Tularemia Viral hemorrhagic fevers
Challenges of the future
- Rapid pop aging will occur throughout most of the world
- Declining pop size will occur in some countries without immigration, due to very low fertility
- Exploding pop size will occur in other countries with the rapid urbanization that goes with it, because they are in earlier stages of the demographic transition.
- Increasing pop size overall
- New emerging and old re-emerging infectious dzs are appearing around the world
- We may see declining life expectancy in some countries due to non-communicable dzs and conditions
- The effects of climate change will be wide-ranging
Descriptive epi definition
The study of the amount and distribution of health states in pops by characteristics of person, place, and time.
Used to identify the existence and extent of health problems in a defined population
What are the three main sources of descriptive epidemiologic information?
Case reports
Case series
Cross-sectional studies
Why does susceptibility to dz increase at higher ages?
Biological clock phenomenon
Cumulative effect of outside stressors or exposures
Latency period
Biological clock phenomenon
Waning of immune system with age
Aging may trigger conditions believed to have a genetic basis
Shortening of telomeres with every cell division
Cumulative effect of outside stressors or expsoures
A cumulative effect of stressors and continuous exposure builds up over time
Example: the cumulative effect of radiation over time may increase the risk of some cancers
Latency period (time to develop chronic dzs)
Higher mortality at older ages may reflect the long latency period between initial exposure and subsequent development of some dzs
The male-female health-survival paradox
Higher mortality rate for males
Higher morbidity rates for females
Why?
Influence of biological differences by sex and/or social differences by gender role may both effect these patterns
Selective factor theory
Healthier ppl are more likely to marry
Better health also leads to longer lasting marriage
Protective factor theory
Marriage protects ppl against poor health
Marriage leads to better health
Social causation hypothesis
Conditions associated with lower social class are more likely to produce illness
Downward drift hypothesis
Unhealthy or less fit persons move to impoverished areas or slide down in social status.
The Hispanic paradox
In spite of relatively low socioeconomic status, similar to African Americans and high morbidity form particular conditions such as diabetes, Hispanic mortality rates appear similar to or even lower than that of non-Hispanic whites
Definition of nativity
Place of origin of the individual
Healthy migrant effect
Observation that healthier, younger persons usually form the majority of migrants
- Often difficult to separate environmental influences in the host country from selective factors operative among those who choose to migrate.
- Migrants usually healthier than the average person in the population from which they came
Acculturation
Modifications that individuals or groups undergo when the come in contact with another country.
Some reasons for place variation in dz
Climate Latitude Geology Ethnic and racial variations Cultural differences (including laws) Poverty vs wealth Gene/environment impact Pollution levels
Secular trend
A gradual change in the frequency of a dz or death rate over long time periods.
Short term variation definition
A brief or unexpected increase or decrease in the rates of a health-related state or event
Cyclic fluctuation definition
An expected periodic change in the frequency of a dz or death rate over time
