Epidemiology Set 1 – Flashcards
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This type of epidemiology focuses on identifying and reporting the distribution and frequency of health events in a population?
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descriptive epidemiology
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This type of epidemiology focuses on the search for the determinants of health outcomes and draws statistical interences about their role in disease causation?
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analytical epidemiology
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This type of epidemiology applies epidemiological prinicples to the judicious use of diagnostics and therapeutics in practicing evidence-based clinical decision making?
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clinical epidemiology
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What is the practice of medicine dependent on population data for diagnosis, treatment, prognosis using a substantial number of cases (population) as evidence for occurence of disease, efficacy of a particular drug and so on?
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evidence based medicine
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What type of disease occurs with a predictable regularity in a population?
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endemic disease
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Can a disease that is endemic become epidemic?
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yes
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What term is often synonymous with the term outbreak and typically used for infectious diseases?
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epidemic
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Can a single case of a disease be an epidemic?
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yes, depending on the disease (rabies, H1N1)
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What are examples of recent epidemics?
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BSE, SARS, Avian influenza, H1N1
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What is a widespread epidemic/epizootic involving more than one country?
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pandemic (panzootic)
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What is irregular, haphazard occurrence of disease, occurs infrequently in a population and is often not rapidly spread?
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sporadic
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What is the ongoing, systematic collection, analysis, interpretation, and dissemination of data regarding a health-related event for use in public health action to reduce morbidity and mortality and to improve health?
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public health surveillance
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What is an individual that harbours an infectious agent or is exposed to a potential causal agent of disease which is usually infectious. Typically used in reference to infectious diseases although in general are also susceptible to non-infectious and chronic diseases?
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host
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What are personal characteristics of an individual or group (age, sex, breed, occupation)?
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demographic
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What are individuals with a particular disease or outcome that meet selected criteria stated by the definition?
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case
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What is a factor that directly influences the occurence of disease or outcome? Synonymous with risk factor or exposure factor in some cases.
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causal factors or determinants
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What is defined as the encounter of a potentially pathogenic agent with a susceptible human/animal host and the host shows an immunologic response?
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infection
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What is defined as a clinically apparent infection, accompanied by overt illness?
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disease
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Whether or not a disease occurs in an individual depends on what 3 factors?
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the host, agent, environment
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The level of disease in a population depends often on an interplay of what 3 factors?
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individual factors, spatial factors, temporal factors
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The occurence of disease and its frequency may be reported in what 4 ways?
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in time, by time series analysis, by host related distribution of disease, by space location
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This disease occurs at expected frequency, present in population or region at all times, usually low and predictable level?
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endemic
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This disease occurs at greater than expected frequency, occurence depicted graphically as epidemic curves?
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epidemic
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This disease is a huge epidemic?
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pandemic
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What is it called when a large number of cases in the population of interest are exposed during a short time period?
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point source epidemic
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In this type of epidemic, exposure to the source is prolonged over an extended period of time and may occur over more than one incubation period?
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continuous common source epidemic
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What are examples of continuous common source epidemic?
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cholera, legionnaire's disease
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This type of epidemic occurs when disease is introduced through a single source of infection in one animal and subsequently transmitted to other animals?
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propagating epidemic
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What is an example of propagating epidemic?
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E. coli O157
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What are examples of sporadic diseases?
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spirocerca lupi, creutzfeidt-jakob disease, rabies, rocky mountain spotted fever
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Patterns of disease occurence are influenced by one of the following 3 trends?
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short term, cyclical, secular trend
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What type of trend has the rise and fall of disease over greater than 1 year, associated with regular, periodic, fluctuations in level of disease occurrence?
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cyclical trends
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What is a special case of cyclical trend where the periodic fluctuations in disease incidence are related to particular seasons?
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seasonal trends
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What are examples of seasonal trends?
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rinderpest, myxomatosis rabbits, leptospirosis
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In seasonal trends, fluctuations are caused by changes in what?
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host density, management, practices, vector dynamics, survival of infectious agents based on environmental factors
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What are overall rises or decline in incidence occuring gradually over long time periods using plotted raw data and other statistical methods?
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secular trends
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Disease occurrence affected by host factors such as what?
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age, sex, breed, immune status, population dynamics
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What is the number of new cases occuring in a population over a defined time period, usually expressed numerically in reference to the populationn at risk?
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incidence
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What is the number of cases present at any given point in time?
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prevalence
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What is prevalence at a point in time, does not take into account the duration of disease, it is a snapshot at this point in time?
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point prevalence
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A change in prevalence can be due to what?
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change in incidence rate, change in average duration of the disease, change in both incidence rate and duration
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What is used to provide information on the locality. Shows how disease moves through the country in space and allows you to see if there are any significant patterns associated with movement?
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aerial maps
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What type of map has each case entered by placing a dot at the appropriate location?
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spot map
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What type of map has areas shaded to show the differences in frequency of disease between cases?
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frequency mapping
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What is used to test hypothesis and plan health policies?
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data modeling
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What is a set of uniformly applied criteria for a particular disease?
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case definition
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What is a measure of the frequency with which new cases occur over a specified time period?
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incidence
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What is the number of cases that are present in a given population?
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prevalence
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What are examples of causal factors?
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agent factors, environmental influences, host factors
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What are examples of environmental influences?
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temperature and humidity
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What is resistance in populations called?
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herd immunity
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What are types of associations?
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non-statistical, statistical, risk factors
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What are risk factors?
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genetic, behavioral, environmental
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What is dose-response relationship?
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it can be shown that varying amounts of the suspected cause are related to varying amounts of the effect.
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Causal factors can be what?
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necessary and sufficient, necessary but not sufficient, sufficient but not necessary, neither sufficient nor necessary
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Which study designs produce the strongest evidence for causal association?
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randomized clinical trial
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What are factors that impair making causal inferences?
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lengthy time interval between "cause" and disease or outcome, multiple "causes" leading to the same disease or outcome, causal factor requires other factors for disease or outcome occurrence
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What is a factor that directly influences the occurrence of disease or outcome. Synonumous with risk factor or exposure factor in some cases?
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causal factor
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What is any or all of the possible changes in health statua that can result from exposure to a causal factor?
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outcome
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what is the result of a cause and includes disease or outcome?
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effect
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What is having contact with a cause of a particular disease or outcome?
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exposure
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What is any systematic error in an epidemiology study that results in an incorrect estimate of the association between exposure and risk of disease?
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bias
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What are the 2 different types of bias?
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selection bias, information bias
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How do you avoid selection bias?
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randomly select subjects so that difference between groups are minimal, ensure that response rates are high, ensure that withdrawl rates from the study are low.
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What is it called when an interviewer interjects his or her bias into interview, the way questions are asked and perceived by respondents affects their response?
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interviewer bias
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What is the ability of respondents to accurately remember exposure or use of family members rather than actual subject to get information?
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recall bias
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What is it called when either exposure or disease outcome is misclassified?
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missclassification bias
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What is the distortion or the masking of an association between an exposure and a disease or outcome because of a third factor?
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confounding
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What are analytical stages of the study?
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restriction, stratification, multivariate
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What is a tecnique that takes into account multiple variables at the same time that may confound the effect of exposure using multiple and linear regression models?
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multivariate analysis
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Descriptive studies describes patterns of disease according to what?
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where disease occurs, who is affected, when disease occurs and suggests possible causal factors for the disease
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What identifies common features amoung a minimum of 5 cases and describes patterns of variability amoung them?
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case series
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What are strengths of case reports?
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quick, cheap, may be first indication of an epidemic or newly recognized disease
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What are weaknesses of case reports?
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there are no control groups, therefore one cannot generalize the findings
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What are strengths of cross sectional studies?
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quick, easy, cheap, often use surveys to do cross-sectional studies
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What are weaknesses of cross-sectional studies?
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cannot assess cause and effect, as looking at one point in time
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What are strengths of ecologic studies?
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allows you to look at patterns and form hypothesis, quick and cheap often using already available information
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What are weaknesses of ecologic studies?
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unable to link exposure to disease and thus unable to test generated hypothesis, unable to control for confounding factors
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What studies seek to identify and explain the causes of disease and assign a numerical value to the effect of a particular risk factor?
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analytical studies
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What is a group of persons who share a common experience within a defined time period?
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cohort
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What study involves comparing disease incidence over time between 2 groups of nondiseased animals that are found to differ on their exposure to a factor of interest?
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cohort study
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If the RR is close to one, how is the exposure associated with the risk of disease?
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exposure is probably not associated with the risk of disease
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If relative risk = 1, then?
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the exposure had no association with the disease or outcome.
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If relative risk is >1 then what?
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a positive association exists between exposure and disease
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If relative risk is <1, then what?
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"exposure" is associated with decrease in risk of disease
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What is the accepted level of confidence that we want for any reported RR?
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95%
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If the 95% includes the null value of 1 then what?
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the finding could be due to chance and the result is not statistically significant at the 95% CI
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If the 95% CI does not include the null value of 1, but falls entirely on either side of it, then what?
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we can say the result is statistically significant
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What are strengths of cohort studies?
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can directly measure incidence, useful when exposure is rare, examine multiple outcomes of a single exposure, describe temporal relationship between exposure and disease, can collect data on possible confounders
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What are weaknesses of cohort studies?
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inefficient for rare diseases, if prospective expensive and long, selection bias, loss to follow-up can affect validity of study
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What is the key point in case-control studies?
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the set of controls represent individuals whose exposure to the factor of interest reflects the exposure in the population from which the cases were selected
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What are strengths of case-control studies?
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efficient for rare diseases, permits study of multiple exposures of an outcome of interest, usually relatively inexpensive and fast, require small number of subjects
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What are weaknesses of case-control studies?
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can't directly estimate incidence or prevalence, problem with selection of controls, human-reported exposure data on animals may be subject to recall bias
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What are issues in all studies, but particularly in case-control studies?
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selection bias, information bias, misclassification bias
