EPI/BIO: EXAM #2 (REVIEW) - QUIZLET

The BEINGS model is a useful paradigm for:

(A) Allocating public health resources
(B) Assessing the impact of herd immunity
(C) Determining the role of social policy on public health
(D) Establishing the importance of social contacts
(E) Evaluating etiologic factors in disease

Evaluating etiologic factors in disease

__________________: This is the number of new cases over a defined study period, divided by the midperiod population at risk.

Incidence rate


(Risk is calculated by total # of pop at risk. Because you use midperiod pop, denominator is different and it turns it into Incidence "Rate")

____________________: This is the observed total deaths in a population, divided by the expected deaths in that population, multiplied by 100.

Standardized mortality ratio

Ratio derived from indirect standardization methods. The observed number of deaths in a population is divided by the expected number of deaths in that population, based on the reference population. The numerator and denominator usually are multiplied by 100 to avoid describing the ratio as a fraction.

This is the proportion of individuals with a given condition who die of the condition.

Case fatality ratio.

Although the case fatality ratio commonly is used to describe the deaths attributable to specific infectious diseases, it also can be used to describe the deaths attributable to any condition.

(Requires that the number of affected individuals and the number of deaths attributable to the condition be known.)

This is the number of live births, divided by the midperiod population.

Crude birth rate.


Technically, this is not a valid rate because not everyone in the denominator can truly be said to be "at risk" for the numerator event (i.e., only women of childbearing age are at risk for bearing children).

This provides the death rate within a defined age range.

Age-specific death rate

Age is one of the strongest predictors of mortality. Death rates that do not reflect the experience of particular age groups are difficult to interpret. Age-specific death rates use the population within a particular age range as the denominator and use deaths within that group as the numerator.

A politician is throwing a luncheon fundraiser serving up various types of seafood including salmon mousse.
Within 24 hours, 11 of the 17 diners experience abdominal pain, vomiting, and diarrhea.

- Of the 11 symptomatic guests, 4 have a fever, and 7 do not;
- 5 have an elevated white blood cell count, and 6 do not;
- 6 ate shrimp bisque, and 5 did not;
- 9 ate salmon mousse, and 2 did not;
and 1 goes on to have surgery for acute cholecystitis resulting from an impacted calculus (stone) in the common bile duct. - Of the 11 symptomatic guests, 10 recover within 3 days; the exception is the senator who underwent surgery and recovered over a longer period. The guests at this luncheon had shared no other meals at any time recently.

The case described:
(A) Is a coincidence until proven otherwise
(B) Is a disease outbreak
(C) Is attributable to bacterial infection
(D) Is not an outbreak because the usual pattern of disease is unknown
(E) Should be investigated by the CDC

Is a disease outbreak

(The situation described represents the unexpected occurrence of disease. Derives from common experience: Nobody expects disease to follow lunch.)

A politician is throwing a luncheon fundraiser serving up various types of seafood including salmon mousse.
Within 24 hours, 11 of the 17 diners experience abdominal pain, vomiting, and diarrhea.
- Of the 11 symptomatic guests, 4 have a fever, and 7 do not;
- 5 have an elevated white blood cell count, and 6 do not;
- 6 ate shrimp bisque, and 5 did not;
- 9 ate salmon mousse, and 2 did not;
and 1 goes on to have surgery for acute cholecystitis resulting from an impacted calculus (stone) in the common bile duct. - Of the 11 symptomatic guests, 10 recover within 3 days; the exception is the senator who underwent surgery and recovered over a longer period. The guests at this luncheon had shared no other meals at any time recently.

The attack rate is:
(A) 4/11
(B) 5/11
(C) 11/13
(D) 1/17
(E) 11/17

11/17.

The attack rate is the proportion of persons exposed who become ill. Number of Sx/Number exposed.

A politician is throwing a luncheon fundraiser serving up various types of seafood including salmon mousse.
Within 24 hours, 11 of the 17 diners experience abdominal pain, vomiting, and diarrhea.
- Of the 11 symptomatic guests, 4 have a fever, and 7 do not;
- 5 have an elevated white blood cell count, and 6 do not;
- 6 ate shrimp bisque, and 5 did not;
- 9 ate salmon mousse, and 2 did not;
and 1 goes on to have surgery for acute cholecystitis resulting from an impacted calculus (stone) in the common bile duct. - Of the 11 symptomatic guests, 10 recover within 3 days; the exception is the senator who underwent surgery and recovered over a longer period. The guests at this luncheon had shared no other meals at any time recently.

An early priority in investigating the phenomenon would be to:
(A) Close the kitchen temporarily
(B) Define a case
(C) Perform a case-control study
(D) Perform stool tests
(E) Submit food samples to the laboratory

Define a case.


Establishing a diagnosis or a case definition is the earliest priority in an outbreak investigation.

A politician is throwing a luncheon fundraiser serving up various types of seafood including salmon mousse.
Within 24 hours, 11 of the 17 diners experience abdominal pain, vomiting, and diarrhea.
- Of the 11 symptomatic guests, 4 have a fever, and 7 do not;
- 5 have an elevated white blood cell count, and 6 do not;
- 6 ate shrimp bisque, and 5 did not;
- 9 ate salmon mousse, and 2 did not;
and 1 goes on to have surgery for acute cholecystitis resulting from an impacted calculus (stone) in the common bile duct. - Of the 11 symptomatic guests, 10 recover within 3 days; the exception is the senator who underwent surgery and recovered over a longer period. The guests at this luncheon had shared no other meals at any time recently.

The best-case definition for the guests' disease would be:
(A) Abdominal pain, vomiting, and diarrhea within 24 hours of the state luncheon
(B) Acute viral gastroenteritis
(C) Staphylococcal food poisoning
(D) The onset of abdominal pain and fever after the state luncheon
(E) Vomiting, diarrhea, and an elevated white blood cell count

Abdominal pain, vomiting, and diarrhea within 24 hours of the state luncheon.

The case definition is required to distinguish between cases and noncases of the disease under investigation.

The ideal case definition would permit the inclusion of all cases and the exclusion of all noncases, providing perfect sensitivity and specificity.

A politician is throwing a luncheon fundraiser serving up various types of seafood including salmon mousse.
Within 24 hours, 11 of the 17 diners experience abdominal pain, vomiting, and diarrhea.
- Of the 11 symptomatic guests, 4 have a fever, and 7 do not;
- 5 have an elevated white blood cell count, and 6 do not;
- 6 ate shrimp bisque, and 5 did not;
- 9 ate salmon mousse, and 2 did not;
and 1 goes on to have surgery for acute cholecystitis resulting from an impacted calculus (stone) in the common bile duct. - Of the 11 symptomatic guests, 10 recover within 3 days; the exception is the senator who underwent surgery and recovered over a longer period. The guests at this luncheon had shared no other meals at any time recently.

Suspecting that the disease is the result of a common source exposure involving contaminated food, the investigators attempt to determine which food is responsible. Their initial task is to:
(A) Analyze food specimens in the laboratory
(B) Close the kitchen
(C) Examine the food preparers
(D) Interview the symptomatic guests to find out what they ate
(E) Perform a case-control study

Interview the symptomatic guests to find out what they ate.

Even before developing hypotheses about the source of infection, investigators would have to characterize this outbreak by time, place, and person.

A screening program analogue to the late look bias is:

(A) Length bias because cases lasting longer are more apt to be detected
(B) Recall bias because only severe illness is recalled
(C) Selection bias because the program selects out asymptomatic illness
(D) Selection bias because the program selects out severe cases
(E) Spectrum bias because the cases are clustered at one end of the disease spectrum

Length bias because cases lasting longer are more apt to be detected

A screening program usually is prospective and would not be subject to _____________. The intent of any disease screening program is to detect asymptomatic and unrecognized cases.

recall bias

A study is conducted to determine the effects of drinking Mountain Dew on a teenager's willingness to bungee jump from frightful heights. A total of 500 teenagers are assembled on the basis of bungee-jumping status: 250 are jumpers, and 250 are not. Of the 250 jumpers, 150 report drinking Mountain Dew. Of the 250 nonjumpers, 50 report drinking Mountain Dew. Most of the nonjumpers report a preference for warm milk.

Which of the following statements is true?
(A) Jumpers and nonjumpers should be matched for beverage consumption
(B) The absolute and relative risk of bungee jumping can be determined from this study
(C) This is a cohort study
(D) This study can be used to calculate an odds ratio
(E) Unanticipated outcomes can be assessed in this study

This study can be used to calculate an odds ratio.

The study described is a case-control study.

A study is conducted to determine the effects of drinking Mountain Dew on a teenager's willingness to bungee jump from frightful heights. A total of 500 teenagers are assembled on the basis of bungee-jumping status: 250 are jumpers, and 250 are not. Of the 250 jumpers, 150 report drinking Mountain Dew. Of the 250 nonjumpers, 50 report drinking Mountain Dew. Most of the nonjumpers report a preference for warm milk.

The odds ratio calculated from this study would give the odds of:
(A) Drinking among jumpers to drinking among nonjumpers
(B) Drinking among nonjumpers to drinking among jumpers
(C) Drinking Mountain Dew to jumping
(D) Jumping among drinkers to drinking among jumpers
(E) Nonjumping among drinkers to nondrinking among jumpers

Drinking among jumpers to drinking among nonjumpers.

The odds ratio in a case-control study is the odds of the exposure in cases relative to controls. The exposure in this study is drinking (specifically, drinking Mountain Dew). Cases are those who bungee jump, whereas controls are those who do not. The odds of drinking Mountain Dew among cases relative to controls is the outcome of interest. As noted, the odds ratio is essentially a measure of the "risk of having the risk factor."

A study is conducted to determine the effects of drinking Mountain Dew on a teenager's willingness to bungee jump from frightful heights. A total of 500 teenagers are assembled on the basis of bungee-jumping status: 250 are jumpers, and 250 are not. Of the 250 jumpers, 150 report drinking Mountain Dew. Of the 250 nonjumpers, 50 report drinking Mountain Dew. Most of the nonjumpers report a preference for warm milk.

The results of this study indicate that:
(A) Bungee jumping and beverage choice are associated
(B) Bungee jumping and beverage choice are causally related
(C) Bungee jumping influences a person's choice of beverage
(D) The choice of beverage influences a person's tendency to bungee jump
(E) There is no association between warm milk and bungee jumping

Bungee jumping and beverage choice are associated.

The odds of drinking Mountain Dew are 6 times as great in cases as they are in controls in this study. There is an apparent association between beverage choice and tendency to jump.

You randomly assign subjects to 2 years of PA school (intervention) or 2 years in graduate school (control), and you test for evidence of burnout (outcome). Of 100 subjects assigned to each condition, you find evidence of burnout in 72 in the PA school group and 43 in the control group.

An appropriate measure of association in this study is:
(A) Incidence density
(B) Power
(C) Likelihood ratio
(D) Odds ratio
(E) Risk ratio

The risk ratio.

The study described is a cohort study, in which subjects are assembled on the basis of exposure status and followed for outcome.

The risk ratio is the outcome measure of a cohort study with a dichotomous outcome.

You wish to determine the proportion of myocardial infarctions that are fatal within 24 hours of their occurrence. You decide to examine the records of all local emergency departments and physicians' offices. You will then calculate the proportion of the reported myocardial infarctions that resulted in death 24 hours or less after the patient was initially seen.

You briefly discuss your plan with a friendly neighborhood biostatistician, who immediately points out that your study is particularly subject to which one of the following forms of bias?
(A) Late look bias
(B) Lead-time bias
(C) Measurement bias
(D) Observer bias
(E) Selection bias

Late look bias

A tendency to detect only the cases of a serious disease that were mild enough to be detected before death.

The mosquito involved in the transmission of malaria assumes the role of:
(A) Animal reservoir
(B) Commensal
(C) Parasite
(D) Surrogate host
(E) Vector

Vector

Data reported for cases of relatively mild diseases, such as chickenpox, could generally be characterized as:
(A) Highly accurate because of active surveillance
(B) Useful for establishing prevalence, but not incidence
(C) Valuable for detecting changes in the pattern of a disease
(D) Valueless because mild diseases are underreported
(E) Valueless because most patients with mild diseases do not present for medical care

Valuable for detecting changes in the pattern of a disease

Underreporting of common and mild diseases is substantial. The number of cases of chickenpox that is reported represents only a portion of the total number of cases of this disease.

The following deaths are reported for a population of 2807 men, age 35 to 68 years: 4 deaths in nonsmokers; 11 deaths in men smoking one-half pack of cigarettes per day; 18 deaths in men smoking one-half to one pack per day; and 43 deaths in men smoking more than one pack per day.

From this, one may conclude that:

(A) Smoking increases mortality
(B) The relationship between mortality rates and smoking is linear
(C) There is a dose-response relationship between smoking and death
(D) To interpret the data, the age at death is required for each case
(E) To interpret the data, the information must be expressed as rates for each risk group

To interpret the data, the information must be expressed as rates for each risk group

Which of the following examples might represent a retrospective cohort study?

(A) Cases of lung cancer assessed for prior exposures
(B) Subjects randomly assigned to active varicella vaccine versus placebo, followed for chickenpox
(C) Subjects with current angina followed for the development of myocardial infarction
(D) Subjects with prior radiation exposure followed for the development of lymphoproliferative cancers
(E) Subjects with skin cancer assessed for lifelong, cumulative sun exposure

Subjects with prior radiation exposure followed for the development of lymphoproliferative cancers

The Physicians' Health Study was a randomized, double-blind, placebo-controlled trial that was designed to test the effects of aspirin and beta carotene on cardiovascular disease and cancer.1 The participants in the trial consisted of approximately 22,000 male physicians who lived in the US and were 40 to 75 years old. The randomization of participants in the study was performed to help achieve which of the following?

(A) Elimination of bias
(B) External validity
(C) Internal validity
(D) Prevention of confounding
(E) Statistical significance

Prevention of confounding