Epidemiology Final
True or False? The point prevalence of a disease is defined as the number of persons ill divided by the total number in the group at a point in time.
True
Which of Mill's four canons suggests that there is an association between frequency of disease and the potency of a causative factor?
concomitant variation
True or False? Randomized controlled trials at the community level are typically used in special situations where there is a simple intervention.
true
True or False? Relative risk is the ratio of the risk of disease among the exposed to the risk among the unexposed.
true
True or False? The proportional mortality ratio (%) is defined as the mortality due to a specific cause during a time period divided by the mortality due to all causes during the same time period times 100.
True
True or False? The three categories of descriptive epidemiologic variables are person, place, and time.
True
True or False? WHO is a major source of information about worldwide international variations in rates of disease.
True
True or False? Reliability refers to the ability of a measuring instrument to give consistent results on repeated trials, regardless of its accuracy.
true
True or False? Specificity refers to the ability of a screening test to identify only nondiseased individuals who actually do not have the disease.
true
True or False? The Freedom of Information Act exempts (does not allow) the release of personal medical data
true
True or False? The National Health Survey consists of several distinct programs conducted by the National Center for Health Statistics.
true
True or False? The purpose of matching in a case-control study is to select the controls in such a way that the control group has the same distribution as the cases with respect to certain confounding variables.
true
True or False? The term attributable risk is also known as the rate difference or risk difference.
true
True or False? Treatment crossover refers to any change of treatment for a patient in a clinical trial that involves a switch of study treatments.
true
True or False? Validity is the ability of a measuring instrument to give a true measure.
true
Sensitivity and specificity of a screening test refer to its:
validity
True or False? Environmental and occupational health problems are a specialization of epidemiology.
True
Refer to the 2 by 2 table below Assuming that the sample table is for a cohort study, define the risk difference or attributable risk:
(A/A+B) - (C/C+D)
A large medical center's oncology program reported an increased number of cases of pancreatic cancer during a certain month. The hospital's epidemiologist decided to research the problem. Tumor registry records were searched to identify all cases of pancreatic cancer during a five-year period; cancer patients were matched with patients treated for other diseases during the same five-year period. All subjects in the study were questioned about lifestyle factors including alcohol, tea, and coffee consumption. The resulting data are as follows: Note: Total number of male cancer patients = 200. Total number of female cancer patients = 150. Total number of male patients (other diseases) = 300. Total number of female patients (other diseases) = 300. Which number best approximates risk associated with alcohol Drinking in Men?
1.37
A new screening test for Lyme disease is developed for use in the general population. The sensitivity and specificity of the new test are 60% and 70%, respectively. Three hundred people are screened at a clinic during the first year the new test is implemented. Assume the true prevalence of Lyme disease among clinic attendees is 10%. Calculate the following value The predictive value of a positive test is:
18.2%
An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea, five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. The attack rate of salmonellosis was:
28.2%
A screening examination was performed on 250 persons for Factor X, which is found in disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained previously. The results are charted below: The specificity of this test is expressed as:
70%
A screening examination was performed on 250 persons for Factor X, which is found in disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained previously. The results are charted below: The sensitivity of this test is expressed as:
80%
True or False? High firearm death rates and homicide rates are indicators of adverse conditions within the community.
True
An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year: The proportional mortality ratio (%) due to roller-skating was:
90/900 x 100
An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year: The crude death rate for all causes was:
900/100,000 × 100,000
True or False? One of three main purposes of descriptive epidemiology is to aid in the creation of hypotheses.
True
True or False? The 1918 Influenza Pandemic is also known as "the Mother of All Pandemics.
True
True or False? The Framingham Heart Study, begun in 1948, pioneered research into coronary heart disease risk factors.
True
As an epidemiologist you are going to investigate the effect of a drug suspected of causing malformations in newborn infants when the drug in question is taken by pregnant women during the course of their pregnancies. As your sample you will use the next 200 single births occurring in a given hospital. For each birth a medication history will be taken from the new mother and from her doctor; in addition, you will review medical records to verify use of the drug. [N.B.: These mothers are considered to have been followed prospectively during the entire course of their pregnancies, because a complete and accurate record of drug use was maintained during pregnancy.] The resultant data are: Forty mothers have taken the suspected drug during their pregnancies. Of these mothers, 35 have delivered malformed infants. In addition, 10 other infants are born with malfunctions. What type of study design is this?
A. Retrospective cohort study
A prophylactic trial is designed to:
A. evaluate the effectiveness of a substance used to prevent disease
True or False? The crude death rate is defined as the number of deaths in a given year divided by a reference population (during mid-point of the year) multiplied by 100,000.
True
Which of the following is usually an aim of epidemiology?
All of the above
True or False? The epidemiologic and clinical descriptions of a disease are different
True
The death rate per 100,000 for lung cancer is 7 among non-smokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among non-smokers and 599 among smokers. The prevalence of smoking in the population is 55%. The population etiologic fraction of disease due to smoking is:
C. 0.83 for lung cancer and 0.18 for coronary thrombosis.
The death rate per 100,000 for lung cancer is 7 among non-smokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among non-smokers and 599 among smokers. The prevalence of smoking in the population is 55%. The relative risk of dying for a smoker compared to a non-smoker is:
D. 10.1 for lung cancer and 1.4 for coronary thrombosis.
The degree of agreement among several trained experts refers to:
D. inter-judge reliability
Which of the following activities characterizes a clinical approach (as opposed to an epidermiologic approach)
Description of specific signs and symptoms in a patient
True or False? Calculation of the standardized mortality ratio is an example of the direct method of age adjustment.
False
True or False? Certain diseases can occur more than once in the same individual during a stated period of time. Repeated cases of the disease have no effect upon incidence rates.
False
True or False? Developmental problems such as congenital birth defects occur primarily late in life.
False
True or False? In current thinking, the term epidemic is used only to describe outbreaks of infectious disease.
False
True or False? John Cassel argued that the agent, host, and environment triad provided an adequate explanation for chronic diseases of non-infectious origin.
False
True or False? Most of the time, epidemiologic researchers confront a problem that has a clear etiologic basis.
False
True or False? Socrates popularized the notion that the environment is associated with human disease
False
True or False? The existence of a dose-response relationship, that is, an increase in disease risk with an increase in the amount of exposure, does not support the view that an association is a causal one
False
True or False? The human biological clock phenomenon is linked to place variation in diseases.
False
True or False? The study of diseases linked to harmful physical energy, such as ionizing radiation, would be outside the scope of epidemiology.
False
The population etiologic fraction for a particular disease from Factor X alone is five times greater than that from Factor Y alone. If the relative risk associated with Factor X is 2, and with Factor Y is 20, which of the following statements is true?
Fewer persons are exposed to Factor Y than to Factor X.
Identify which of the following six types of study designs most appropriately characterizes the situation described below. The physical examination records of the incoming freshmen class of 1935 at the University of Minnesota are examined in 1980 to see whether their recorded height and weight at the time of admission to the university are related to their chance of developing coronary heart disease by 1981.
Historical prospective cohort study
Which type of evaluation requires the collection of baseline information before the program starts?
Impact evaluation
A new blood test has been developed to screen for disease Z. Researchers establish 50 units as a cut point above which a test is considered positive and thereby indicative of disease. The test manufacturers determine that the test's sensitivity is unacceptably low. However, the manufacturers are not concerned with the specificity and do not want the cost of the test to rise. How can they improve the sensitivity of the test?
Lower the cut point below 50 units.
A five-year prospective cohort study has just been completed. The study was designed to assess the association between supplemental vitamin A exposure and mortality and morbidity for measles. The RR for incidence of measles was 0.75 and the RR for measles mortality was 0.5. Which statement is correct?
One of the problems that this study may have faced is individuals lost to follow-up during the five-year period
A causal association between factor and outcome can refer to
Selection bias: survival bias
The death rate per 100,000 for lung cancer is 7 among non-smokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among non-smokers and 599 among smokers. The prevalence of smoking in the population is 55%. On the basis of the relative risk and etiologic fractions associated with smoking for lung cancer and coronary thrombosis, which of the following statements is most likely to be correct?
Smoking seems much more likely to be causally related to lung cancer than to coronary thrombosis.
Which of the following activities characterizes an epidemiologic approach (as opposed to a clinical approach)?
Surveillance of a population
True or False? An example of operations research is using epidemiology to plan the placement of health services in a community.
True
A new antibody test detects serum antibodies against virus X (sensitivity 99%, specificity 90%). When applied in a group of hospitalized patients diagnosed as having virus X infections, the test is found to have a positive predictive value of 85%. When used to screen a group of healthy blood donors for virus X infections, the test is found to have a positive predictive value of 30%. Which of the following best explains this difference between the positive predictive values?
The prevalence of virus X infection is higher among the hospital patients than among blood donors
A null hypothesis is most similar to which of the following?
True
True or False? A prerequisite for using direct age adjustment is that the age-specific death rates in the study population must be stable.
True
The population etiologic fraction is a measure of the proportion of the disease rate in a population attributable to the exposure of interest. This measure of effect is influenced by:
a and c
Forty mothers have taken the suspected drug during their pregnancies. Of these mothers, 35 have delivered malformed infants. In addition, 10 other infants are born with malfunctions. Suppose that a relative risk of 0.5 has been found. Which interpretation might follow?
a and d
The Vital Statistics Registration System in the U.S. collects data on all vital events including:
a b and c
An abrupt drop in mortality due to a specific disease from one year to the next is most likely due to
a change in the International Classification of Disease (ICD) system
Which of the following data sources is most likely to provide a representative sample of the general health status of a population
a morbidity survey of the general population
Increases in lung cancer mortality, especially among women, illustrate which of the following trends in disease occurrence?
a new epidemic disorder
Practical considerations in the design of cohort studies do not usually include:
age of the investigator
Before utilizing data for an epidemiologic study, the researcher must first consider the:
all of the above
Controlled clinical trials enable researchers to:
all of the above
Cyclic variations in the occurrence of disease may reflect:
all of the above
Examples of exposure data in ecologic studies include:
all of the above
In a survey which uses lay interviewers to interview one person about his or her health and the health of household members, the sources of error include:
all of the above
Morbidity surveys of the general population:
all of the above
Nested case-control studies:
all of the above
Surrogate endpoints in clinical trials may include:
all of the above
The phases of the policy cycle include:
all of the above
The uses of epidemiology include:
all of the above
To assess clinical end points, investigators:
all of the above
What factors should be considered in measuring long-term changes in disease frequency over time?
all of the above
Which of the following reasons might account for place variation in disease?
all of the above
Which types of health issues are likely to be addressed in community trials?
all of the above topics
Choose the correct answer. Data on morbidity in the U.S. armed forces include:
all statements are correct
Descriptive epidemiology has the following characteristics (Choose the incorrect option):
allows causal inference from descriptive data
Ecologic studies:
are a good approach for generating hypotheses
If it is accepted that an observed association is a causal one, an estimate of the impact that a successful preventive program might have can be derived from:
attributable risk
The purpose of a double-blind study is to:
avoid observer and interviewee bias.
What data source has the advantage of being almost nearly complete in the U.S.?
b and c
Descriptive epidemiology characterizes the amount and distribution of disease within a population and enables the researcher to:
b and c only
Schistosomiasis is an example of:
biological agents-helminth
Which of the following is not a method for controlling the effects of confounding in epidemiologic studies?
blinding
Which form of prevention takes place after the precursors of disease interact with the host?
both a and B
A causal association between factor and outcome can refer to
c and d
Cohort study is to risk ratio as:
case-control study is to odds ratio
Cautious use of information from death certificates is warranted because:
cause of death information may not be correct
Examples of descriptive epidemiologic studies do not usually include:
cohort studies
Identify which of the following six types of study designs most appropriately characterizes the situation described below. To test the efficacy of a health education program in reducing the risk of foodborne and waterborne diseases, the residents of two Peruvian villages were given an intensive health education program. At the end of two years, the incidence rates of important water-borne and food-borne diseases in these villages were compared with those in two similar control villages without any education program.
community trial
Phase III clinical trials for a cancer drug involve:
comparing survival rates for the new drug versus extant therapies
A test that determines whether disease is actually present is a:
diagnostic test
What is one of the widely used sources of statistical data on cancer?
disease registries
True or False? A case-control study is purely a descriptive (as opposed to analytic) study design
false
True or False? A cross-sectional study allows the demonstration of a time sequence between exposure and disease.
false
True or False? Diseases that have only human reservoirs and are transmitted from person to person are the zoonoses.
false
True or False? Health insurance statistics provide a generally representative picture of the health status of the United States population.
false
True or False? Incubation period refers to the time between the start of an infection and the beginning of the period of communicability.
false
True or False? It is possible for a measure to be valid but unreliable.
false
True or False? Physical environmental factors in the natural history of disease include weather, temperature, and biologic components.
false
True or False? The National Ambulatory Medical Care Survey is a continuing probability survey of physicians who practice in public settings such as V.A. centers.
false
True or False? The presence of an infectious agent is a sufficient cause for outbreaks of infectious disease to occur.
false
True or False? The term attributable risk is defined as the ratio of the incidence of a disease among exposed individuals to the incidence among non-exposed individuals.
false
Which of the following individuals helped draw people's attention to the method of cohort analysis?
frost
An ambispective cohort study is also known as a:
historical prospective study
Someone suggests immunization as a means of reducing disease, specifically the feared UJ (uderlinger jacamoodi). What part of the disease cycle is he or she trying to affect?
host
An epidemiologic experiment is performed in which one group is exposed to a suspected factor and the other is not. All individuals with an odd hospital admission number are assigned to the second group. The main purpose of this procedure is to:
improve the likelihood that the two groups will be comparable with regard to known and unknown confounding factors.
You are investigating the role of physical activity in heart disease and suggest that physical activity protects against having a heart attack. While presenting these data to your colleagues, someone asks if you have thought about confounders such as factor X. This factor X could have confounded your interpretation of the data if it:
is a factor associated with physical activity and heart disease.
Case-control studies are among the best observational designs to study diseases of:
low prevalence
A null hypothesis is most similar to which of the following?
negative declaration
A double-blind study of a vaccine is one in which:
neither observers nor subjects know which subject receives the vaccine and which receives a placebo.
When assessing a positive relationship between alcohol consumption and oral cancer using a case-control study, increasing the sample size of the study will result in which of the following? i. A lower p value ii. A greater odds ratio iii. A smaller 95% confidence interval iv. A higher disease prevalence Circle the best response.
none of the above
The site where a disease agent enters the body is the:
portal of entry
According to the natural history of disease model, the time before the precursors of disease and the host interact is called the period of
prepathogenesis
The difference between primary and secondary prevention of disease is
primary prevention means control of causal factors, while secondary prevention means early detection and treatment of disease.
The best routinely available sources of data regarding the incidence of respiratory disease outbreaks and other rapidly spreading conditions are:
reports of absenteeism from work and school
The strategy which is not aimed at reducing selection bias is:
standardized protocol for structured interviews.
In case-control studies, the odds ratio is used as an estimate of the relative risk. In order for this approximation to be reasonable, some conditions must be met. Which of the following conditions is not necessary in order to use the odds ratio to estimate the relative risk?
the exposure in the question is rare in the population
The risk of acquiring a given disease during a time period is best determined by:
the incidence rate (cumulative incidence) for that disease in a given period of time.
Successful treatment programs that would shorten the duration of a disease primarily affect:
the prevalence of the disease
The major disadvantage of crude rates is that:
they do not permit comparison of populations that vary in composition.
There has been an increase in the number of epidemiologic studies reported in medical journals because:
they interest the public and physicians concerned with preventive medicine.
A major advantage of cohort studies over case-control studies with respect to the role of a suspected factor in the etiology of a disease is that:
they permit direct estimation of risk of disease in those exposed to the suspected factor.
True or False? A registry is a centralized database of information about a disease.
true
True or False? Administration of immune globulin confers passive immunity.
true
True or False? An ecologic comparison study is sometimes called a cross-sectional ecologic study.
true
True or False? An ecologic study is one that examines a group as a unit of analysis.
true
True or False? An enzootic disease among animals is similar to an endemic disease among humans.
true
True or False? Controls are needed in a case-control study to evaluate whether the frequency of a factor or past exposure among the cases is different from that among comparable persons who do not have the disease under investigation.
true
True or False? If a disease is fatal, virulence can be measured by the case fatality rate.
true
True or False? In community intervention studies, it is important for the investigator to evaluate whether a program has achieved its intended results before assuming the benefits of the intervention.
true
True or False? Lyme disease is an example of a disease transmitted by arthropod vectors.
true
True or False? Nativity refers to place of origin of an individual.
true