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Epidemiology Final Exam 2


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What is screening?
Organized, population-wide approaches to disease detection; an examination of a group of usually asymptomatic people to detect those with a high probability of having a given disease; aim is to detect the disease before the usual time of diagnosis.
What is case-finding?
Opportunistic attempts at early detection when a person comes into contact with the health system for another reason; diagnostic approach used when a person is already suspected of having a disease.
What are the levels of prevention?
(1) Primary Prevention
(2) Secondary Prevention
(3) Tertiary Prevention
What is primary prevention?
Preventing a disease or disorder before it happens; health promotion, health education, and health protection are examples.
What is secondary prevention?
Prevention aimed at the health screening and detection activities used to identify disease; aims to block the progression of disease or prevent an injury from developing into an impairment or disability.
What is tertiary prevention?
Prevention whose aim is to retard or block the progression of a disability, condition, or disorder in order to keep it from advancing and requiring excessive care; limiting any disability by providing rehabilitation where disease, injury, or a disorder has already occurred and has caused damage.
What are the strategies for prevention?
(1) high-risk strategy
(2) mass strategy
What is the high-risk strategy for prevention?
a targeted rescue operation for vulnerable individuals; well matched to individuals and their concerns which should improve the benefit-to-risk and benefit-to-cost ratios; if problem is confined to an identifiable minority and can be successfully controlled in isolation.
What is the mass strategy for prevention?
Better approach for common or widespread problems; aims to reduce health risks of the entire population; immunization programs and fluoridation of water are examples.
What is a risk factor?
Anything that increases a person's chance of developing a disease (behavioral, environmental, genetic, and social)
What are at-risk behaviors?
An activity performed by persons who are healthy, but are at greater risk of developing a particular disease, condition, or disorder because of the behavior.
What are predisposing factors?
Those existing factors or conditions that produce a susceptibility or disposition in a host to a disease or condition without actually causing it; precede the direct cause.
What is blinding?
Used in experimental studies to minimize potential bias from a placebo effect.
What are the levels of blinding?
(1) single blind (subjects)
(2) double blind (investigators)
(3) triple blind (analysis)
What is a single blind study?
Placebo-controlled study where the subjects are blind but investigators are aware of who is receiving the active treatment.
What is a double blind study?
Neither the subjects nor the investigators know who is receiving the active treatment.
What is a triple blind study?
Not only are the treatment and research approaches kept a secret for the subjects and investigators, but the analyses are completed in a way that is removed from the investigators.
What are the implications related to blinding?
In some situations, it may be impossible or unethical to blind; may be problematic to blind in drug studies where a treatment has characteristic side effects; building side effects into a placebo may also be unethical.
What are the strengths of blinding?
Demonstrate cause-effect relationships; may produce a faster and cheaper answer than observational studies; only appropriate approach for some research questions; allow investigators to control the exposure levels as needed.
What are the weaknesses of blinding?
Often more costly in time and money; many research questions are not suitable for experimental designs because of ethical barriers and because of rare outcomes; many research questions are not suitable for blinding; standardized interventions may be different from common practice; may have limited generalizability due to the use of volunteers, eligibility criteria, and loss to follow-up.
What are the criteria for establishing causal associations?
(1) temporal relationships (absolute requirement)
(2) strength of association
(3) consistency of association
(4) Dose-response relationship
(5) biological plausibility
(6) specificity
(7) experimental evidence
What is a temporal relationship?
Exposure must precede the disease.
What is the strength of the association?
Stronger associations between exposure and outcome variables increase the likelihood of there being a causal association; stronger associations are less likely to be explained by chance, bias, or confounding.
What is the consistency of the association?
When associations are replicated by different investigators in different settings with different methods.
What is the dose-response relationship?
When an increasing amount of exposure increases the risk of disease.
What is biological credibility?
Is the association biologically supported? Biological assessment often involves experiments in controlled laboratory environments.
What is experimental evidence?
Experimental study design is the best for establishing cause-effect relationships because blinding is effective at controlling bias, and randomization is effective for balancing out the effect of known and unknown confounders.
What is specificity?
If an association is limited to a specific outcome then we would expect to see that outcome in individuals with a specific disease.
What is eradication?
Removal of a disease from all human populations.
What is elimination?
Removal of a disease from defined areas.
What is control?
Reduction of a disease below the threshold of public health significance.
What are the 5 elements of causation?
(1) consistency of the cause-effect association
(2) strength of the cause-effect association
(3) specificity of the cause-effect association
(4) time factor aspects of the cause-effect association
(5) coherence of the cause-effect association.
What is field epidemiology?
The application of epidemiology under a set of general conditions: (1) the problem is unexpected, (2) a timely response may be demanded, (3) travel to and work in the field is required by epidemiologists to solve the problem, and (4) the investigation time is likely to be limited because of the need for a timely intervention.
What are the steps (14) in conducting a field investigation?
(1) establish the existence of an epidemic (or outbreak), (2) confirm the diagnosis, (3) establish criteria for case identification, (4) search for missing cases, (5) count cases, (6) orient the data according to person, place, and time, (7) classify the epidemic, (8) determine who is at risk of becoming a case, (9) analyze the data, (10) formulate a hypothesis, (11) test hypotheses, (12) develop reports and inform those who need to know, (13) execute control and prevention measures, and (14) administration and planning activities.
How are epidemics classified?
(1) common source
(2) propagated
(3) mixed
What is a common source epidemic?
at a specific point, through intermittent or continuous exposure to a source over days, weeks, or years.
What is a propagated epidemic?
through gradual spread from person-to-person
What is a mixed epidemic?
combination of both common source and propagated outbreaks; typically begin with a common source and are then propagated from person-to-person.
How do you construct a web of causation?
(1) identify the problem, affirm the condition, and obtain an accurate diagnosis of the disease, (2) place the diagnosis at the center or bottom of the web, (3) brainstorm and list all possible sources for the disease, (4) brainstorm and list all possible risk factors and predisposing factors of the disease, (5) develop sub-webs and tertiary level sub-webs for the various branches of the web, if needed, (6) organize and arrange lists of sources and risk factors from general and most distant from the disease, in steps, being more specific and focused as the steps move closer toward the diagnosis of the disease, and (7) develop and work through causation decision trees for each element under consideration on the way toward the diagnosed disease.
Which studies are best for determining cause-effect?
The double-blind randomized clinical trial because blinding minimizes bias and randomization minimizes confounding.
What are the study designs effective at establishing causal association in rank order? (control confounding)
(1) randomized controlled trials, (2) community trials, (3) prospective cohort studies, (4) retrospective cohort studies, (5) case-control studies, (6) cross-sectional studies, (7) ecologic studies, and (8) case report or case series studies.

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