Epi Midterm Study Guide Flashcards
Epidemic
The occurrence in a community or region disease in excess of normal expectancy
Pandemic
The epidemic occurring worldwide, in a wide area, crossing international boundaries, and affecting many people.
Epidemiology
The distribution and determinants of health and diseases, morbidity, injuries, disability, and mortality in populations.
Study of distribution and determinants of disease frequency in human populations, applied to study and control health problems.
Name and discuss three of the key characteristics of epidemiology vs. clinical medicine
The formulation of hypotheses, and exploring causal relationships between exposures and health outcomes, solves a broad range of health-related problems.
Define risk factors. What are some examples of risk factors for the leading causes of disease?
The exposures associated with disease, morbidity, or mortality
Distinguish between the descriptive and analytic approaches.
Descriptive: epidemiological studies that characterize the amount and distribution of health within a population
Analytic: examines causal (etiologic) hypotheses regarding the association between exposures and health outcomes.
Identify an exposure and an outcome from a research abstract
Exposure with disease-causing factor, which leads to outcomes; or all possible results that may stem from exposure to causal factor
What does “distribution” refer to in the definition of epidemiology?
This implies that the occurrence of the disease and other health outcomes varies in populations
What do “determinants” refer to in the definition of epidemiology?
A collective or individual risk factor that is casually related to a health condition, outcomes, or other defined characteristic.
Differentiate between morbidity and mortality.
Morbidity: illness from disease or condition
Mortality: causes of death
Maternal mortality rate
The maternal mortality ratio (MMR) is defined as the number of maternal deaths during a given time period per 100,000 live births during the same time period
Infant mortality
The infant mortality is the death of an infant before his or her first birthday. The infant mortality rate is the number of infant deaths for every 1,000 live births.
General fertility rate
The number of resident live births for a specified geographic area (nation, state, county, etc.) during a specified period (usually a calendar year) divided by the female population age 15-44 years (usually estimated for a mid-year) for that area, and the resulting fraction multiplied by a 1,000.
Fetal mortality
The Fetal death refers to the spontaneous intrauterine death of a fetus at any time during pregnancy
Crude birth rate
The Number of deaths over a given period divided by the person-years lived by the population over that period. It is expressed as a number of deaths per 1,000 population
Differentiate rate, ratios, and proportions
Ratio: magnitude of 2 quantities or comparison of any 2 values. (don’t have to be related). Results in “_____ to one”
Proportion: division of 2 related numbers. Num is subset of denom . percentage, fraction, decimal
Rate: division of one number by another; time is in denominator. Measures risk
** ratios = proportions, proportions ≠ ratio
Which measure of central location is most commonly used with the standard deviation?
Mean, median, and mode
Which measure of spread is most affected by an extreme value?
range
Which measure of central location is most appropriate to report for skewed data?
median
Describe the relationship between the measures of central location in normally distributed data
Normal distribution data will not be skewed. The mean, median, and mode are the same.
Define incidence vs prevalence
Incidence: the speed of the occurrence of new cases of cases in a population at risk during a specific time period. Transition from 1 state to another. Denom = pop at risk
Prevalence: measures existing cases of disease in total population over a specific time period. Involves being in a state of disease. Denom = total pop at risk
Proportion of pop with disease!!
Describe how mortality influences prevalence. Provide examples to illustrate the relationship between mortality, incidence, and prevalence.
Mortality will decrease the prevalence of disease if the pop died with the disease of interest.
What are the limitations of using crude rates in epidemiology? Why might crude rates not provide an accurate representation of a population’s health status or disease burden?
Crude rates are not an accurate representation because they only take the average rate of disease and do not consider confounding factors such as demographics
Define and explain alternative measures that can be used to overcome the limitations of crude rates in epidemiological studies.
The studies need to include demographic factors. A crude death rate in one region might be different than another, but those rates do not take population amount, age range, and other factors.
Fertility vs birth rate
Fertility rates: number of live births reported in an area during a given time interval divided by the number of women ages 15-44 in the area.
Birth rates: the number of live births in an area during a given time period, such as a year per the resident population at the midpoint of the year.
Populations vs samples
Populations: a collection of people that share observable characteristics
Samples: a subgroup that has been selected from the population
Provide examples of when it is appropriate to use a sample rather than studying an entire population in epidemiological research.
When it is too difficult or the population is simply too large to study, a sample can help gauge an idea of the population. The sample must be representative of the population and randomly selected.
Identify the person, place, and time characteristics for the following scenarios:
Epidemiologists investigate an outbreak of Salmonella infections in Coconino County and find that most cases occur among individuals who recently attended a county fair. They also note that the outbreak coincided with the annual county fair event. This combination of factors helps identify the source of the outbreak and implement targeted prevention measures.
Person: Those who attended the fair
Place: Coconino County Fair
Time: The time interval that the fair was operating
Variable types
Variables: used to describe a quantity that can vary
Age, height, weight, sex
Discrete variables: finite, countable, limited numbers.
Household size, number of doctor visits
Continuous variables: infinite possibilities for values
Age, height, weight, HR, cholesterol
If you take a measurement of BP, it becomes discrete.
Identify the person, place, and time characteristics for the following scenarios:
Researchers find that asthma rates are higher in urban areas with high levels of air pollution, such as near industrial zones or major highways.
Person: People who live in these areas
Place: Geographic urban areas that have high levels of air pollution
Time: This disease occurs in those who live in areas with high levels of air pollution, and they are especially at risk during rush hour traffic
Identify the person, place, and time characteristics for the following scenarios:
Epidemiologists investigate a cholera outbreak in a coastal town and discover that cases are clustered in areas with poor sanitation and contaminated drinking water sources.
Person: Those who live in coastal towns with poor sanitation
Place: Coastal towns with poor sanitation
Time: This disease occurs when individuals are exposed to contaminated water sources
Identify the person, place, and time characteristics for the following scenarios:
In a factory, workers who handle asbestos-containing materials are found to have a higher risk of developing mesothelioma, a rare cancer.
Person: Factory workers
Place: Inside factories with asbestos-containing materials
Time: This disease occurs while people work in the factory
Identify the study design:
Researchers collect data on the average income and the prevalence of a specific health condition for different regions within a country. What study design is this, and what are its advantages and disadvantages?
ecological
Identify the study design:
A study involves the collection of detailed information on a small group of patients diagnosed with a rare disease to describe their clinical characteristics and outcomes. What study design is this, and what are its advantages and disadvantages?
Case-series
Identify the study design:
A new drug with in vitro activity against HIV is tested on a population of patients with Western-blot confirmed HIV infections. Out of the 200 individuals in the patient population, 100 are chosen at random to receive the drug. The drug, which is tasteless, is administered in a cup of orange juice; the other patients receive pure orange juice. Neither the nurses, doctors, nor patients know which patients receive the drug. At the end of the study period, the number of CD4+ T cells is determined for all of the subjects.
Experimental, randomized control trial
Identify the study design:
500 women aged 40-53 who present for routine check-ups are asked about their meat consumption. 20% of the women turn out to be vegetarian. During the ensuing 5 years, 5 vegetarians and 43 non-vegetarians developed colorectal cancer.
Prospective cohort
Identify the study design:
A group of patients with lung cancer is matched to a group of patients without lung cancer. Their smoking habits over the course of their lives are compared. On the basis of this information, researchers compute the odds of smoking among patients with lung cancer compared to the odds of smoking among those without lung cancer.
Case-control
Identify the study design:
Persons diagnosed with new-onset Lyme disease were asked how often they walk through woods, use insect repellant, wear short sleeves and pants, etc. Twice as many patients without Lyme disease from the same physician’s practice were asked about the same questions, and the responses of the two groups were compared.
Case-control
Identify the study design:
Researchers in India wanted to evaluate the prevalence of HIV and risk behaviors in male sex workers as well as the association between sociodemographic factors and HIV. The data were collected in June 2009 using interviewer-administered questionnaires (for sociodemographic and behavior data), clinical eval for sexually transmitted infections, and serological evaluation for STIs (like HIV).
Cross-sectional
Identify the study design:
The objective of a recently published study was to determine if fine particulate matter (a measure of air pollution) was associated with COVID-19 fatalities. Average fine particulate matter from 400 counties in Germany was obtained from the European Environment Agency. Daily numbers of confirmed COVID-19 deaths per 100,000 inhabitants were obtained from the Robert Koch Institute. The correlation between average fine particulate matter air pollution and COVID-19 deaths was estimated. Higher levels of fine particulate matter was positively correlated with COVID-19 deaths.
Ecological
Identify the study design of the following examples:
Researchers select a random sample of 500 college students from a specific university. This sample is representative of the entire student population in terms of age, gender, and academic majors. The researchers administered a questionnaire to the selected students at a single point in time, typically over the course of a few days or weeks.
Simple random sampling
Identify the study design of the following examples:
A study compares two groups: one receiving a new drug, and the other receiving a placebo. What study design is this, and what are its advantages and disadvantages?
Randomized control study
Identify the study design of the following examples:
A study collects data at a single point in time, surveying a large group of individuals about their current dietary habits. What study design is this, and what are its advantages and disadvantages?
Cross-sectional study
Identify the study design of the following examples:
Researchers follow a group of smokers and non-smokers over 10 years, tracking the development of lung cancer. What study design is this, and what are its advantages and disadvantages?
Prospective cohort study
Identify the study design of the following examples:
Researchers analyze data from medical records to compare the outcomes of patients who received a specific treatment with those who did not. What study design is this, and what are its advantages and disadvantages?
Case-control???
Identify the study design of the following examples:
A study examines a rare disease and selects cases from a population with the disease and controls from the same population without the disease. What study design is this, and what are its advantages and disadvantages?
Case-control
Define the terms “exposure,” “outcome,” and “population at risk” in the context of epidemiology.
Exposure: contacts with disease-causing factors; the amounts of the factors that impinge upon a group of individuals.
Outcome: results that may arise from an exposure to a causal factor. Conditions, chronic disease, injuries, etc.
Population at risk: members of the population who are capable of developing a disease or condition
Describe the difference between cross-sectional, case-control, cohort, and ecological studies.
Cross-sectional: a type of descriptional study designed to estimate the prevalence of a disease or exposure
Case-control: the study that compares individuals who have a disease with individuals who do not have the disease in order to examine differences in exposure or risk factors for the disease.
Cohort: a population group or subset thereof that is followed over a period of time.
Ecological: type of research design that assesses the correlation between exposure rates and disease rates among different groups or populations over the same time period. Unit of analysis is the group
Interpret the meaning of an odds ratio (OR) equal to 1 in a case-control study.
The OR of more than 1 suggests a positive association between the exposure of disease and another outcome
OR less than 1 indicates that the exposure might be a protective factor.
OR equivalent to 1 = no exposure between exposure and outcome (154)
Explain the difference between relative risk (RR) and absolute risk (AR). How are they used in epidemiological studies?
Relative risk: ratio of the risk of disease or death among the exposed to the risk among the unexposed. Relative risk= IR in the exposed/IR in the unexposed
Absolute risk:
How is selection bias different from information bias in epidemiological studies? Give examples of each.
Selection bias: bias in the estimated association or effect of an exposure on an outcome that arises from procedures used to select individuals for the study.
Information bias: deviations from the
If an epidemiological study reports an odds ratio (OR) of 2.0 for a particular exposure and outcome, how would you interpret this result?
The score of 2.0 suggests that the odds of the disease are about two times higher among the exposed persons than among the nonexposed persons
