Final exam

Epidemiology has been termed the 'basic science of Public Health'. The role of epidemiology in the health sciences covers all of the following except:

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In the process of establishing whether exposure to a certain risk factor is associated with unhealthy outcome, you expect distortions of accurate measure of the purported relationship to be hampered by?

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which of the following is NOT a reason for selecting the use of a case-control study design?

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key feature of the cross-sectional study design

-Measurements made at a single period of observation-Participants not chosen due to exposure or outcome-Measurements made on all participants-Main uses:-To study trends-To understand the characteristics of a population-To generate hypotheses of the relation between exposure and outcome

federal agencies that oversee human subjects research

NIH, FDA, department of education, department of energy,

surveillance systems of disease indicators

animal populations, environmental data, hazard surveillance in the workplace, drug/biological utilizations, student and employee data

limitations of longitudinal studies

feasibility, precision, long time

INTERMEDIATE genetic susceptibility

genetic configuration causes susceptibility

compliance

may be less in participants who believe they are not receiving the treatment, may be better in those who understand the principles on which the intervention is based,

survelliance system as information loops

multiple players, begins when disease is reported, doesn't end until information is related to those responsible for disease prevention

RR = 1

no association

endemic refers to

normal prevalence of disease in an area

analytic studies are two types

observational and experimental

ethic issues in epidemiology

obtaining consent, privacy, interpretation of risk, informing subjects of findings, objectivity of the researcher,

analytic approach to retrospective case control design

odds ratio

A specific case definition is one that

or tight case definition is one that is likely to include only (or mostly) true cases, but at the expense of excluding milder or atypical cases.

the case-fatality rate for a specific disease refers to

proportion of patients with a given disease who will die from that disease, and thus reflects the seriousness of the condition.

only direct method of measuring risk

prospective cohort study

you are interested in establishing whether intra-uterine adverse-health events results in adulthood diseases, what study design is most appropriate if you want to establish risk

prospective cohort study

goals of the IRB

protect subjects, promote public health good by supporting valid research

RR < 1

protective factor

disadvantages of retrospective case control design

recalled information, validation of exposure can be difficult, unable to control extraneous variables, may be difficult to find an aproppriate control,

analytic approach to prospective cohort studies

relative risk, risk ratio

tasks of the IRB

review all research, approve before it begins, review periodic reports, approve any changes to research, additional scrutiny for vulnerable populations

advantages of case studies

rich sources of hypotheses, unusual disease presentations are shared with the larger scientific commuunity

incidence density assumes

risk of outcome is constant for the entire duration fo the study, rate of disease is the same for dropouts as for those who continue under observation, disease lasts for at least 1 full unit of observation

lead time bias

screening detects disease earlier in its natural course which leads to false improvement in survival time

The incidence of colon cancer in a population may be decreased by

screening for prevention,

bias in longitudinal studies

selection, migration, missclassification, detection

Attributes of a Surveillance System

simplicity, felxibility, acceptabilitiy, sensitiivity, representativeness, timeliness, resource requirements

MOST genetic susceptibility

specific gene defect

prenatal genetic screening

specificity is key, most disorders are generally autosomal recessive

which of the following may occur during the incubation period

spread of disease without symptoms

disadvantages of cross-sectional studies

subclinical cases are missed, cannot measure risk, cannot make causal inferences, cannot test an hypothesis,

advantages of retrospective case control design

suited to rate disease, inexpensive, existing records can be used, no risk to subjects

purpose of genetic epidemiology

susceptibility or resistance to disease, and variates in response to treatment.

false negative

test result negative but disease present

false positive

test result positive but no disease

sensitivity

the ability of the test to identify correctly those persons tested who truly have the disease

specificity

the ability of the test to identify correctly those who do not have the disease

validitity

the extent to which a test measures or predicts what it is supposed to

true positive

the patient has the disease and the test is positive

analytic epidemiology

the study of risk factors and the relationships among risk factors for the purpose of understanding the etiology of the disease or condition

public health surveillance

the systematic collection, analysis, interpretation, and dissemination of health data describes and monitors health events, sets priorities, assists in planning public health interventions

volunteer bias

those with reason to worry are more likely to get screened, screening leads to higher number of cases

List three things that could lead to an increase in the prevalence of disease

treatment but no cure, less deaths, more detection, migration into an area

Years of Potential Life Lost is a particularly important concept for tracking the societal impact of pediatric diseases

true

a basic assumption of epidemiology is that disease occurrence is not random

true

herd immunity can protect all group members from certain infectious disease even though they all may not be immune

true

one way infectious disease can be transmitted is via FOMITE

true

incidence density assumes that following one person for ten years is equivalent to following ten people for one year

true?

limitations of the national notifiable disease reporting system

underreporting, lack of representativeness, lack of timeliness, inconsistency of case definition

the hallmark feature of an analytic epidemiologic study is:

use of an appropriate comparison group

screening test

used to seperate those who have a high probability of having the disease from a large group of apparently well persons, not intended to be diagnostic,

sources of data

vital statistics, morbidity data, outpatient health care data, surveys of health,

relative risk

what is my risk given that I have been exposed compared to those unexposed, incidence in exposed / incidence in unexposed

absolute risk

what is my risk jut by virture of being a member of the population, incidence in the population

odds ratio

what is the chance of developing the disease in exposed persons compared to the chance for disease in those not exposed

true negative

without disease and negative screening test

techniques to minimize bias in observational studies include?

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which of the following is a key assumption involved in the use of life-table analysis?

.Life-table analysis depends upon a consistent rate of survival during all periods of the study. Changes in the rate of survival may be due to external influences that are operating at later times on only a portion of the initial population. Since those who have died earlier in the study period will not experience these external influences, the comparison between periods is rendered invalid.

important concepts of genetic epidemiology

1. common disease are controlled by several genes 2. there are geographical disease differences because of genes and environment 3. genes for essential proteins tend to be conserved 4. variable genes have less clinical revelance

Wilson-Junger Criteria

1. condition should be an important health problem 2. accepted treatment for the disease 3. facilities for treatment should be available 4. recognizable latent or early symptomatic stage 5. suitable test for examination 6. acceptable test 7. condition should be understood 8. policy on whom to treat 9. cost of case finding should be balanced 10. case-finding should be a continual process

sequence of genetic studies

1. look for gene marker 2. explore nearby genes 3. establish functional association of genetic defect with disease

Kappa statistic

A measure of the degree of nonrandom agreement between observers of the same categorical variable.

kappa statistic

A measure of the degree of nonrandom agreement between observers of the same categorical variable.

common screening tests

BP, blood sugar, pap smear, cholesterol, mammography, PSA, occult blood for colon CA,

Describe the steps that the health department should take to investigate this outbreak

Early steps include confirming that the number of cases exceeds the expected number, verifying the diagnosis, and preparing for field work (which includes talking with laboratorians about specimen collection). Next steps include conducting surveillance to identify additional cases; analyzing the data by time, place, and person; generating hypotheses; and evaluating those hypotheses (for example, by conducting a case-control study)

Kaplan-Meier method

Estimates survival function: uses survival times to estimate the proportion of people who would survive a given length of time under the same circumstances, new interval with each event

types of genetic studies

HLA associations, linkage analysis

attributable risk

How much of the disease that occurs can be attributed to a certain exposure?

postive predictive value

Increase with prevalence of disease, probability the a positive is actually positve

medical surveillance

The monitoring of potentially exposed individuals to detect early symptoms of disease.

Standardized Mortality Ratio (SMR)

The observed number of deaths divided by the expected number of deaths and multiplied by 100. SMR is regarded as a measure of the relative risk of the studied group to die of a particular condition

negative predictive value

The probability that a person with a negative test result is truly disease free refers to what value?

case study characteristics

a single event, series of events is described, often unusual or noteworthy because of temporal or spatial clustering

hurdles in the study of chronic diseases

absence of an agent, multifactoral etiology, long latency, indefinite onset

the number of deaths from lung cancer during 2005 in persons 40-49 years divided by the 2005 midpoints population of persons 40-49 years old is defined as:

age specific mortality rate

the epidemiologic triangle is best described as

agent, host, environment

active surveillance

better data, expensive, specific disease, limited period of time

can establish causality

clinical trial

intent to treat analysis

compares the outcome of interest between the study groups based on the treatment to which why were randomized regardless of whether the individuals actually took their assigned treatment or not

strengths of longitudinal studies

correct temporal relationship, disease rates obtained directly, can evaluate rare exposures, can evaluate multiple outcomes from a single exposure, generally good exposure informaiton

statistical approach to cross sectional studies

correlation

advantages of cross sectional studies

data can be collected consistently for an entire population, can determine the magnitude of the problem, can identify possible causes, inexpensive, useful to assess health status and healthcare needs of a population

purpose of cross-sectional studies

describe distribution of disease its associated risk factors at one point in time, a "snapshot" of the experience of a defined population at a given time or ate a specified point in life

in a retrospective cohort study, the main difference from the prospective cohort study is?

disease is identified first then looks for exposure where prospective starts with exposure

participation of screening decreases with

disease phobia, stigma, unpleasant treatements, socioeconomic status, lack of access

LEAST genetic susceptiblity

external factors only

reporting is an obligation of

health professionals, medical examiners, administrators of health facilities and schools, lab directors

the ability of a single person to remain free of clinical illness following exposure to an infectious agent is known as

immunity

if we wish to measure risk in the population then we should look at the:

incidence

RR > 1

increased risk

a good surveillance report can serve to

inform and motivate

disadvantages of case studies

inherently biased, cannot test an hypothesis, no time dimension, no comparison group

retrospective case control design

investigates an association of a prior exposure to disease by determining is the exposure was more frequent among diseased cases, exposure is recollected after the development of disease

when an infectious disease outbreak occurs, investigators usually construct an 'epidemic curve'. This is because:

it can help identify type of outbreak and incubation periods

state health department requires reporting of a disease if

it causes serious disease or death, has potential to affect additional people, can be controlled or prevented, outbreaks with high incidence must be reported, and occurence of an unusal disease

John Snow's investigation of cholera is considered a model for epidemiological field investigations because it included a:

it included a biologically plausible (but not popular at the time) hypothesis that cholera was water-borne, a spot map, a comparison of a health outcome (death) among exposed and unexposed groups, and a recommendation for public health action. Snow's elegant work predated multivariate analysis by 100 years.

participation in screening increases with

knowledge of condition, perception of surceptiiblity, knowledge of treatment

incomplete reporting is caused by

lack of knowledge of what is reportable, lack of knowledge how to report, perception that it is not important

length time bias

less agressive disease allows time for screening leads to false benefit of screening