HLTH 503 Final

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:

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%. Among smokers, the etiologic fraction of disease due to smoking is:

0.90 for lung cancer and 0.29 for coronary thrombosis.

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

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: [Refer to the chapter titled "Study Designs: Cohort Studies"]

10.1 for lung cancer and 1.4 for coronary thrombosis.

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. The relative risk between exposure to the drug and malformations is:

14

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. The number of individuals who both did not take the drug and did not give birth to infants who were malformed was:

150

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%

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 number of false positives is:

81

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 × 100 - see page 142

Which of the following examples involves indirect transmission of disease?

A and B

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

The Vital Statistics Registration System in the U.S. collects data on all vital events including:

A, B, and C

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 cause-specific mortality rate from roller-skating was:

ANSWER IS NOT - 90/600 × 100,000 - see page 138

Cohort study is to risk ratio as:

ANSWER IS NOT - A and C

Which of the following activities characterizes a clinical approach (as opposed to an epidermiologic approach)?

ANSWER IS NOT - C. Examination of disease occurrence among population groups - see page 13

Identify which of the following six types of study designs most appropriately characterizes the situation described below. You would like to assess the effectiveness and efficiency of delivering health services through your clinic. After selecting a 10% sample of all patient visits during the past six months, you are able to characterize the patient population who used your clinic in terms of age, race, sex, method of referral, diagnostic category, therapy provided, method of payment, daily patient load, and clinic staff work schedules.

ANSWER IS NOT - Community trial

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?

ANSWER IS NOT - Prospective cohort study - see page 343

An abrupt drop in mortality due to a specific disease from one year to the next is most likely due to:

ANSWER IS NOT - coding mistake when using the International Classification of Disease (ICD) system

Which of Mill's four canons suggests that there is an association between frequency of disease and the potency of a causative factor?

ANSWER IS NOT - difference

Morbidity surveys of the general population:

ANSWER IS NOT - typically use a scientifically designed representative sample

Before utilizing data for an epidemiologic study, the researcher must first consider the:

All of the above

Choose the correct answer. Clinical data sources include:

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

Information about the cause of death listed on a death certificate may be unreliable because:

All of the above

The uses of epidemiology include:

All of the above

What factors comprise the epidemiologic triangle?

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 - see page 397

An attack rate is an alternative incidence rate that is used when:

All 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 the above

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

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

Both C and D

Identify which of the following six types of study designs most appropriately characterizes the situation described below. To test the efficacy of vitamin C in preventing colds, army recruits are randomly assigned to one of two groups: one in which 500 mg of vitamin C is administered daily, and one in which 500 mg of a placebo is administered daily. Both groups are followed to determine the number and severity of subsequent colds.

Clinical trial

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

What is one of the widely used sources of statistical data on cancer?

Disease registries

The phases of the policy cycle include:

False

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? A therapeutic trial involves the study of the effectiveness of a substance or program to prevent disease.

False

True or False? An ecologic comparison study is sometimes called a cross-sectional ecologic study.

False

True or False? An important risk factor for the population is always important for the individual.

False

True or False? Antigenicity of an infectious agent is measured by the secondary attack rate.

False

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? Health insurance statistics provide a generally representative picture of the health status of the United States population.

False

True or False? Herd immunity must be 100% to confer protection to a group.

False

True or False? In current thinking, the term epidemic is used only to describe outbreaks of infectious disease.

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? John Snow is credited with developing the smallpox vaccination.

False

True or False? Physical environmental factors in the natural history of disease include weather, temperature, and biologic components.

False

True or False? Socrates popularized the notion that the environment is associated with human disease.

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 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 presence of an infectious agent is a sufficient cause for outbreaks of infectious disease to occur.

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

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

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.

Which of the following individuals helped draw people's attention to the method of cohort analysis?

Frost

Which type of evaluation requires the collection of baseline information before the program starts?

Impact evaluation

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:

NOT THE ANSWER B. (A/A+B) / (C/C+D)

A null hypothesis is most similar to which of the following?

Negative declaration

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. see page 422

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.

Identify which of the following six types of study designs most appropriately characterizes the situation described below. The entire population of a given community is examined, and all who are judged to be free from bowel cancer are questioned extensively about their diets. These people then are followed for several years to see whether or not their eating habits will predict their risk of developing bowel cancer.

Prospective cohort study

In a study to determine the incidence of a chronic disease, 150 people were examined at the end of a three-year period. Twelve cases were found, giving a cumulative risk of 8%. Fifty other members of the initial cohort could not be examined; 20 of these 50 could not be examined because they died. Which source of bias may have affected the study?

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

Which of the following statements most accurately expresses the breeder hypothesis for schizophrenia?

The conditions of life in lower-class society favor its development.

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 question is rare in the population.

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

True or False? A dynamic population is one that adds new members through immigration and births and loses members through emigration and deaths.

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

True or False? A registry is a centralized database of information about a disease.

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? An example of operations research is using epidemiology to plan the placement of health services in a community.

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? Environmental and occupational health problems are a specialization of epidemiology.

True

True or False? Health phenomena may show cyclic variations in a person's response to temporary stressors.

True

True or False? High firearm death rates and homicide rates are indicators of adverse conditions within the community.

True

True or False? If a disease is fatal, virulence can be measured by the case fatality rate.

True

True or False? Molecular epidemiology applies the techniques of molecular biology to epidemiologic studies.

True

True or False? Nativity refers to place of origin of an individual.

True

True or False? One of three main purposes of descriptive epidemiology is to aid in the creation of hypotheses.

True

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? Reliability refers to the ability of a measuring instrument to give consistent results on repeated trials, regardless of its accuracy.

True

True or False? Sensitivity refers to the ability of a screening test to correctly identify all screened individuals who have a disease.

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? Survival curves may be used to portray patients' survival in clinical studies.

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

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 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

True or False? The epidemiologic and clinical descriptions of a disease are different.

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 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? The three categories of descriptive epidemiologic variables are person, place, and time.

True

True or False? Validity is the ability of a measuring instrument to give a true measure.

True

True or False? When the duration of a disease becomes short and the incidence is high, the prevalence becomes similar to incidence.

True

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 - p. 115

True or False? Cohort studies preserve the temporality of cause (exposure) happening before the effect (disease)

True - see page 324

Sensitivity and specificity of a screening test refer to its:

Validity

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

A major advantage of community trials is that they are:

able to estimate directly the realistic impact of behavior change

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

The purpose of a double-blind study is to:

avoid observer and interviewee bias.

Schistosomiasis is an example of:

biological agents-helminth

A person with an inapparent infection:

can transmit the infection to others

Cautious use of information from death certificates is warranted because:

cause of death information may not be correct

Subjects for an exposure-based cohort study would be selected most appropriately from:

certain occupational groups such as battery workers

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

A prophylactic trial is designed to:

evaluate the effectiveness of a substance used to prevent disease

An ambispective cohort study is also known as a:

historical prospective study

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

The degree of agreement among several trained experts refers to:

inter-judge reliability

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 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.

Failing to account for age cohort effects in smoking prevalence may:

obscure the fact that there had been a shift in the age of onset for lung cancer toward earlier ages.

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 purpose of randomization is to:

reduce error that results from assignment to study conditions

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

Cyclic variations in the occurrence of pneumonia and influenza mortality may reflect:

seasonal variations in cases of influenza.

The strategy which is not aimed at reducing selection bias is:

standardized protocol for structured interviews.

Using epidemiology for operational research involves:

study of community health services

The incidence of a disease is five times greater in men than in women, but the prevalence shows no sex difference. The most likely explanation is that:

the duration of the disease is greater in women.

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