Epidemiology Practice Problems Part 2

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smokers 84 2,913 non-smokers 87 4,913 The incidence of CHD that can be attributed to smoking is:

10.6 per 1,000

The population of Newbury, NJ was 234,000 on June 30, 2005. Between 1/1/05 and 12/31/05 the number of new active tuberculosis cases occurring was 36. There were 410 active TB cases on the rolls Division of Communicable Diseases at the Newbury Health Department on June 30, 2005. Two patients died during 2005 of multiple drug resistant TB. The annual mortality rate from all causes in Newbury, NJ in 2005 was 11 deaths per 1,000 people What is the incidence rate of tuberculosis in Newbury, NJ in 2005?

15.4 per 100,000

In a hypothetical cohort study of the risk of smoking and coronary heart disease (CHD), 163 smokers developed CHD and 6,837 did not. 153 nonsmokers developed CHD and 7,847 did not. (Hint: construct a 2 x2 table before proceeding) What was the incidence of CHD in smokers in this study?

23.3 per 1,000

Results of a 10-year cohort study of smoking and oral cancer are shown below: healthy 48 1952 non-healthy 22 7978 The incidence of oral cancer among smokers is:

24.0 per 1,000

The town of Newbury, NJ had two deaths in 2014 from tuberculosis. One person was 45 years and the other person was 57 at the time of death. What were the Years of Potential Life Lost (YPLL) to TB using the standard of 75 years for normal life.

48 YPLL

The incidence of emphysema among smokers in a community is 20.0 per 100,000 per year. The incidence of emphysema among non-smokers in this community is 2.0 per 100,000 per year. The proportion of smokers in this community is 40%. What proportion of the risk of emphysema in the total community can be attributed to smoking?

78.3%

Factor A- Factor A + Factor B - 6 14 Factor B + 16 All the questions in this set refer to the data in this table. A hypothetical cohort study investigated the effect of two risk factors on the incidence of Disease X. The following table displays the incidence rates (cases per 1,000) of Disease X following exposure to Factor A & Factor B from the study. What is the attributive risk for Disease X from exposure to Factor A?

All of the following statements concerning the Kaplan-Meier method of survival analysis are true EXCEPT for:

calculates a new survival rate for all the subjects for each year of the study

When the results of a randomized trial show a statistically significant difference between the outcome of the control group and the experimental group, this indicates that the study has external validity

false

all risk factors for disease can be modified

false

The population of Newbury, NJ was 234,000 on June 30, 2005. Between 1/1/05 and 12/31/05 the number of new active tuberculosis cases occurring was 36. There were 410 active TB cases on the rolls Division of Communicable Diseases at the Newbury Health Department on June 30, 2005. Two patients died during 2005 of multiple drug resistant TB. The annual mortality rate from all causes in Newbury, NJ in 2005 was 11 deaths per 1,000 people What was the proportionate mortality for tuberculosis in Newbury, NJ in 2005?

0.078%

The population of Newbury, NJ was 234,000 on June 30, 2005. Between 1/1/05 and 12/31/05 the number of new active tuberculosis cases occurring was 36. There were 410 active TB cases on the rolls Division of Communicable Diseases at the Newbury Health Department on June 30, 2005. Two patients died during 2005 of multiple drug resistant TB. The annual mortality rate from all causes in Newbury, NJ in 2005 was 11 deaths per 1,000 people What was the case-fatality rate for tuberculosis in Newbury, NJ in 2005?

0.49%

Complete the second row of the chart. What is the probability of surviving the second year of the study if a person survived the first year?

0.527

Complete the Kaplan-Meier data chart to answer the following question. What is the cumulative probablity of survival after 20 months in this study?

0.779

Newbury, NJ had a population of 250,000 people on Jun 30, 2014.The mortality rate for Newbury in 2014 was 11 per 1,000. During the year 2014 there were a total of 215 active case of tuberculosis (TB) on the rolls of the Division of Communicable Disease. In 2014 there were 15 cases of TB newly diagnosed during the year. Two TB patients died from multiple drug resistant TB. What was the mortality rate from TB in 2014?

0.8 per 100,000

The population of Newbury, NJ was 234,000 on June 30, 2005. Between 1/1/05 and 12/31/05 the number of new active tuberculosis cases occurring was 36. There were 410 active TB cases on the rolls Division of Communicable Diseases at the Newbury Health Department on June 30, 2005. Two patients died during 2005 of multiple drug resistant TB. The annual mortality rate from all causes in Newbury, NJ in 2005 was 11 deaths per 1,000 people What was the TB-specific mortality rate in Newbury, NJ in 2005?

0.85 per 100,000

1.218

1.223

Two thousand people, 1500 women and 500 men, were surveyed for the signs and symptoms of rheumatic arthritis (RA). 50 people met the American Rheumatoid Association criteriafor RA. 45 of those case were women. What is the sex-specific prevalence of RA for men in this population?

10 per 1,000

What are the odds that a control was a heavy consumer of alcohol?

109/666

How many patients were censored in this Kaplan-Meier data chart?

A colon cancer screening test iwas preformed on patients between the ages of 50 to 75 years. The screening test has a sensitivity of 80% and a specificity of 90%. If the prevalence of colon cancer is 20 per 1,000 in the population tested, what is the positive predictive value of this screening test?

14%

What is the CRUDE MORTALITY RATE from Disease A for community Y (Assuming that only people 45 years and older contract Disease A)?

14.5 per 1,000

A school nurse examined a population of 1,000 children in an attempt to detect hearing loss. The prevalence of hearing loss in this population is known to be 5%. The sensitivity of the examination is 90% and its specificity is 90%. All children labeled as "positive" (i.e., suspected of having hearing loss) by the school nurse are sent for examination by an ENT MD. The sensitivity of the MD's examination is 98% and its specificity is 95%. How many children are labeled "positive" by the school nurse?

140

The population of Newbury, NJ was 234,000 on June 30, 2005. Between 1/1/05 and 12/31/05 the number of new active tuberculosis cases occurring was 36. There were 410 active TB cases on the rolls Division of Communicable Diseases at the Newbury Health Department on June 30, 2005. Two patients died during 2005 of multiple drug resistant TB. The annual mortality rate from all causes in Newbury, NJ in 2005 was 11 deaths per 1,000 people. What is the prevalence of tuberculosis in Newbury, NJ in 2005?

175.2 per 100,000

Factor A- Factor A + Factor B - 6 14 Factor B + 16 All the questions in this set refer to the data in this table. A hypothetical cohort study investigated the effect of two risk factors on the incidence of Disease X. The following table displays the incidence rates (cases per 1,000) of Disease X following exposure to Factor A & Factor B from the study. Assume that the effect of risk factors A &B is additive. What would be the attributive risk for the combined exposure to risk factors A & B?

19.1 per 1,000

Using a matched analysis what is the odds ratio for breast cancer in reserpine users as compared to non users?

2.0

Factor A- Factor A + Factor B - 6 14 Factor B + 16 All the questions in this set refer to the data in this table. A hypothetical cohort study investigated the effect of two risk factors on the incidence of Disease X. The following table displays the incidence rates (cases per 1,000) of Disease X following exposure to Factor A & Factor B from the study. What is the relative risk for Disease X after exposure to Factor A?

2.3

Factor A- Factor A + Factor B - 6 14 Factor B + 16 All the questions in this set refer to the data in this table. A hypothetical cohort study investigated the effect of two risk factors on the incidence of Disease X. The following table displays the incidence rates (cases per 1,000) of Disease X following exposure to Factor A & Factor B from the study. What is the relative risk for Disease X after exposure to Factor B?

2.67

One hundred persons are tested for Disease X. There are twenty-two (22) positive tests, ten (10) of which were true positives and there were twelve (12) false positives. Seventy-eight (78) people tested negative for the disease, sixty-eight (68) were true negatives and ten (10) were false negative tests. What is the prevalence of disease among the tested population?

20%

The population of a city on February 15, 2005, was 36,600. The city has a passive surveillance system that collects hospital and private physician reports of influenza cases every month. During the period between January 1 and April 1, 2005, 2,200 new cases of influenza occurred in the city. Of these cases, 775 persons were ill with influenza according to surveillance reports on April 1, 2005. The prevalence rate of active influenza as of April 1, 2005, was:

22 per 1,000

Factor A- Factor A + Factor B - 6 14 Factor B + 16 All the questions in this set refer to the data in this table. A hypothetical cohort study investigated the effect of two risk factors on the incidence of Disease X. The following table displays the incidence rates (cases per 1,000) of Disease X following exposure to Factor A & Factor B from the study. Assume that the effect of risk factors A & B is additive. What would you predict for the incidence rate of Disease X in persons exposed to both Factor A and Factor B?

Two thousand people, 1500 women and 500 men, were surveyed for the signs and symptoms of rheumatoid arthritis (RA). 50 people met the American Rheumatism Association diagnostic criteria for RA. 45 of the cases were women. What is the prevalence of rheumatoid arthritis in this population?

25 per 1,000

A group of researchers are interested in conducting a clinical trial to determine whether a new cholesterol-lowering agent was useful in preventing coronary heart disease (CHD). They identified 12,327 potential participants for the trial. At the initial clinical exam, 309 were discovered to have CHD. The remaining subjects entered the trial and were divided equally into the treatment and placebo groups. Of those in the treatment group, 505 developed CHD after 5 years of follow-up while 477 developed CHD during the same period in the placebo group. What was the prevalence of CHD at the initial exam?

25.1 per 1000

In 2005 there were 9,000 deaths due to lung disease in miners aged 20-64 years. The expected number of death in this occupational group based on age specific death rates from lung diseases of all males aged 20-64 years, was 3,600 during 2005. What is the standardized mortality ratio (SMR) for lung disease in miners in 2005?

250

A prevalence survey conducted from January 1 through December 31, 2003 identified 580 new cases of tuberculosis in a city of 2 million persons. The incidence rate of tuberculosis in this population has historically been 1 per 4,000 persons each year. What is the incident rate of tuberculosis per 100,000 persons in 2003?

29 per 100,000

In a Latin American country with a population of 5 million, 150,000 deaths occurred in the year ending on Dec 31, 2012. There were 30,000 deaths from pneumonia among the 200,000 cases of pneumonia diagnosed that year. What was the crude mortality for this country for the year 2012?

30 per 1,000

Factor A- Factor A + Factor B - 6 14 Factor B + 16 All the questions in this set refer to the data in this table. A hypothetical cohort study investigated the effect of two risk factors on the incidence of Disease X. The following table displays the incidence rates (cases per 1,000) of Disease X following exposure to Factor A & Factor B from the study. If the effect of exposure to both risk factors is multiplicative, what would you predict would be the incidence rate for Disease X after exposure to both risk factors?

37.3

The following data regarding lung cancer and CHD mortality for a cohort study of male physicians,appears in the table below: The background risk per 1,000 for coronary heart disease among smokers is:

413

140 10 coronary heart 669 413 disease The background risk of CHD mortality among smokers is:

413 per 100,000

A school physician examined a population of 1,000 school schildren in an attempt to detect heart disease. The prevalence of heart disease in this population is known to be 10%. The sensitivity of the physicians's eamination is 70% and its specificity is 90%. What is the positive predicitve value of the physician's physical exam?

43.8%

What is the odds ratio that an esophageal cancer patient is a heavy user of alcohol compared to a control subject that is a heavy user of alcohol?

5.64

6 per 1,000

6 per 100,000

Factor A- Factor A + Factor B - 6 14 Factor B + 16 All the questions in this set refer to the data in this table. A hypothetical cohort study investigated the effect of two risk factors on the incidence of Disease X. The following table displays the incidence rates (cases per 1,000) of Disease X following exposure to Factor A & Factor B from the study. If the effect of exposure to both risk factors is multiplicative, what would you predict would be the relative risk for Disease X after exposure to both risk factors?

6.2

The cause-specific age-adjusted mortality rates for the USA in 2004 are listed in the table below. What is the proportionate mortality for stroke in the USA in 2004?

6.3% (50/800)

A randomized clinical trial for a new vaccine was undertaken. Subjects were randomly assigned to three treatment groups: A, who received the "new" vaccine; B, who received the "old standard" vaccine, and C, who received a placebo. Each group was followed to determine the incidence of the disease. The following incidence rates were found: A: 26/1,000 person-weeks B: 35/1,000 person-weeks C: 68/1,000 person-weeks The efficacy of the new vaccine compared to the placebo is:

61.8%

Two neurologists, Dr. J and Dr. K, independently examined 70 magnetic resonance images (MRIs) for evidence of brain tumors. As shown in the table above, the neurologists read each MRI as positive or negative for brain tumors. Based on the above information, the overall percent agreement between the two doctors including all observations is:

62.9%

What is the age-adjusted mortality rate for population A from Disease X using the combined populations as the standard reference population? (There is one correct answer)

7.2 per 1,000

79.7

What is the AGE-SPECIFIC mortality rate for 45-64 year old persons in COMMUNITY X from Disease A?

8.63 per 1,000

The above data is from a cohort study exploring the possible causal relationship between cigarette smoking and oral cancer. The relative risk for oral cancer in smokers compared to non-smokers is:

8.73

A prostate specific antigen (PSA) test is a quick screening test for prostate cancer. A researcher wants to evaluate it for two groups. Group A consists of 1,500 men who have biopsy-proven prostate cancer while group B consists of 3,000 age- and race- matched men all of whom showed no cancer on prostate biopsies. The results of the PSA screening tests are shown above in the table. What is the positive predictive value (PPV) of the screening test for the combined group?

83%

86 per 100,000

What is the age-adjusted mortality rate for community X (using the combined population of Community X & Y as the standard population) of for Disease A? (Assuming that only people 45 years or older contract Disease A)

9.57 per 1,000

The following data regarding lung cancer and CHD mortality for a cohort study of male physicians lung cancer 140 10 coronary heart 669 413 disease The proportion attributable risk of lung cancer mortality among smokers is:

92.9%

1,000 persons are tested for Disease A. There are 220 positive tests. 200 are true positives and 20 are false positives. 780 people tested negative for Disease A. There were 10 false negative and 770 true negatives. What is the sensitivity of this test for Disease A?

95.2%

What are the odds that a subject with esophageal cancer was a heavy consumer of alcohol?

96/104

97.5%

A disease has an incidence of 10 per 1,000 persons per year, and 80% of those affected will die within 1 year. Prior to the year 2000, only 50% of cases of the disease were detected by physician diagnosis prior to death. In the year 2000, a lab test was developed that identified 90% of cases an average of 6 months prior to symptom onset; however, the prognosis did not improve after diagnosis. Comparing the epidemiology of the disease prior to 2000 with the epidemiology of the disease after the development of the lab test, which statement is true concerning the disease in 2000?

Both the incidence and the prevalence of the disease are greater in 2000

By using the two test tests as described, more children who have normal hearing will be correctly identified than by using either test alone

In a study of 500 cases of a disease and 500 controls, the suspected etiologic factor is found in 400 of the cases and 100 of the controls. The absolute risk (incidence) of disease in persons with the factor is:

Cannot be calculated from the data given.

Communities P and Q have equal-age adjusted mortality rates. Community P has a lower crude mortality rate that Community Q. One may conclude that:

Community P has a younger population than Community Q

In a study of Peruvian migrants to the USA, the Standardized Mortality Ratios (SMR) in the above table were found for Disease Y. Expected values for calculations of SMRs were derived from the general US population. These finding suggest that:

Environmental factors are the major determinants of the SMRs

A case-control study was done that purported to show an association between coffee consumption and the risk of pancreatic cancer. The cases were patients hospitalized on a hospital gastroentestinal service to have a staging work-up of their pancreatic cancer. The controls were chosen from other patients on the gastrointestinal service who were hospitalized for other GI conditions such as ulcer disease. When this study was repeated by several different investigators, they chose control patients who were not suffereing from GI disorders. The second studies showed no association between coffee consumption and the risk of pancreatic cancer. What is the best possible explanation for this?

GI patients with ulcers don't as much drink coffee as the usual populace because the acidity in coffee increases their abdominal pain

The median survival time of children with leukemia treated with a combination drugs and radiation is reported to be 28.2 months. For such patients:

Half will survive less than 28.2 months

For herd immunity to exist in a population, certain conditions must be met. Which one of the following statements is NOT a condition for herd immunity?

Immuninization rates must exceed 98% for herd immunity to show its effects

A series of 1,000 female patients with breast cancer included 32 who were pregnant. From this, one may conclude

In this series, 3.2% of the breast cancer patients were pregnant

For colorectal cancer diagnosed at an early stage, the disease can have 5-year survival rates of greater than 80%. Which answer best describes early stage colorectal cancer?

Incidence rate will be much higher than mortality rates

A new screening program was instituted in a certain country. the program used a screening test that is effective in detecting cancer Z at an early stage. assume that there is no effective treatment for this type of cancer and, therefore, that the program results in no change in the usual course of the disease. Assume also that the rates noted are calculated from all known cases of cancer Z and that there were no changes in the quality of death certification of this disease what will happen to the apparent incidence rate of cancer Z in the country during the first year of this program?

Incidence rate will increase

Which of the following is an advantage of a case-control study?

It is possible to study more than one exposure at a time.

Which of the following statements about the various etiologic study designs is FALSE:

One of the main problems in a nested case-control study is recall bias

In comparing the mammography readings of two radiologists who evaluated the same set of 600 screening mammograms for presence of breast cancer from a generally representative sample of women from the population

Overall percent agreement calculated for both readers may conceal significant disagreements regarding positive tests

Based on the information given above, one may conclude:

Persons born in 1941-1950 are at higher risk of dying from disease X than persons born in 1931-40 or in 1960-1980.

In 2012 investigators started a study of the association between cholesterol levels and peripheral vascular disease in a group of 2,000 residents who had entered into a over-55 residential planned community in 1992. At the time of their medical examination on entry into the community, each subject had a baseline cholesterol level drawn. The investigators determined exposure categories using a cutoff level of 240 and above as high cholesterol levels and levels 239 and below as normal cholesterol levels.There were 1,000 residents in each category. The investigators determined that by 2012, 75 cases of peripheral vascular disease had developed among the residents. 50 of those cases were in residents with "high cholesterol". Using this reported study data, what is the risk measure that was chosen to assess the strength of the association between cholesterol level and peripheral vascular disease?

RR=2

Which factor can best increase the positive predictive value estimated for a screening program?

Selection of a screening population at high risk for the disease.

Attributable risk is:

The number of cases that are explained by a given factor

Case-fatality rate for a given disease refers to

The percentage of deaths among the cases of the disease

Which of the following statements about incubation period for a disease is TRUE?

The person does not show any signs or symptoms of the disease.

In a community-based hypertension testing program called HT-Aware, the detection level for high blood pressure is set at 140 mmHg for systolic blood pressure. A separate testing program called HT-Warning in the same community sets the level at 130 mmHg for high systolic blood pressure. Which statements are likely to be true?

The sensitivity of HT-Warning is greater than the sensitivity of HT-Aware

In a community-based diabetes screening program, the diagnosis of diabetes was made if the fasting blood glucose level was 140 mg/dl or greater. In a hospital-based program the diagnosis of diabetes was made if the fasting blood sugar was 120 mg/dl or greater. which statement is likely to be true.

The sensitivity of the hospital testing program is greater than the community screening program.

Test A has a sensitivity of 95% and a specificity of 80%. Test B has a sensitivity of 80% and a specificity of 98%. In a community of 10,000 people with 5% prevalence of the disease, Test A has always been given before test B. What is the best reason for changing the order of these tests?

The total number of false positives found by both tests is decreased if test B is given first.

Controls are needed in case-control studies because:

They allow evaluation of whether or not the frequency of exposure among cases is different from that among comparable persons without the disease

An advantage of identifying persons in a high risk group for a specific disease is that preventive efforts can be designed to target that group

True

In assessing the relative merits of case-control and cohort studies, a correct statement is:

Unlike case-control studies, cohort studies permit direct determination of incidence rates

In 1976, a randomized clinical trial was carried out which compared total mastectomy and segmental (partial) mastectomy in the treatment of breast cancer. A total mastectomy was carried out on any woman assigned to the segmental mastectomy group if it was impossible to obtain tumor-free margins (i.e., it seemed that the tumor had spread). For statistical analysis, these women were retained in the segmental group. Was this procedure reasonable?

Yes, excluding these women from statistical analysis would have biased the outcome in favor of the segmental mastectomy group.

A randomized, controlled clinical trial is conducted to test a vaccine for preventing influenza. After administration of vaccine to subjects in the treatment group and placebo to subjects in the control group, all subjects were followed to determine the incidence rates of influenza. The incidence rate in the vaccine group was 50/1000 person-weeks, and in the placebo group it was 70/1000 person-weeks. The main purpose of randomization in this study is to:

avoid bias in the assignment of treatment groups

the diagram below shows the natural history of disease X: Assume that early detection of a disease X through screening improves prognosis. In order for a screening program to be most effective, at which point in the natural history in the diagram must the critical point be?

between B and C (earliest possible detection of disease X by any screening technique AND usual time of diagnosis of Disease X)

"Any systematic error in the design, conduct or analysis of a study that results in a mistaken estimate of an exposure's effect on the risk of disease", is a definition of:

bias

From hospital charts of 40 patients diagnosed as having dengue fever, it was noted that a large proportion had fasted during the two-week period preceding onset. To determine if fasting is associated with clinical dengue, data on a series of 40 patients with non-dengue febrile illness were collected. These patients were matched for age, sex, and race to the dengue patients. The hospital charts of these patients were then reviewed to determine whether they also fasted prior to their illness. Classify the study described above as to the following:

case-control study

In which group are all study designs in that group able to show the temporal relationship between exposure and subsequent disease?

case-control study, prospective cohort study, retrospective cohort study

A new screening program was instituted in a certain country. the program used a screening test that is effective in detecting cancer Z at an early stage. assume that there is no effective treatment for this type of cancer and, therefore, that the program results in no change in the usual course of the disease. Assume also that the rates noted are calculated from all known cases of cancer Z and that there were no changes in the quality of death certification of this disease what will happen to the apparent case-fatality for cancer Z in the country during the first year of this program?

case-fatality will decrease

If the incidence of a disease remains constant but the duration of the disease is shortened by a new, effective treatment, the prevalence of the disease will:

decrease

in general, screening should be undertaken for diseases with the following feature(s):

diseases with a natural history that can be altered by medical intervention

A study design that is based on the group charateristics is called

ecologic study

You want to test whether migraine headaches are associated with drinking milk. You compare milk intake in several geographic areas with the occurrence of migraine headaches. This type of study is known as a/an:

ecologic study

A key premis of epidemiology is that disease is randomly distributed in a population.

false

If there is an association between an exposure to a risk and the development of a disease, it follows logically that a causal relationship must exist

false

Ignaz Sommelweis promoted handwashing in order to prevent diarrhea

false

It is necessary to understand the pathogenesis of a disease to prevent it.

false

Physical therapy for persons who have had a stroke is a type of secondary prevention

false

Population based approaches to prevention are generally not cost effective

false

The incubation period is the interval from the receipt of the disease until the time of its diagnosis

false

The major purpose of randomization in a randomized trial is to ensure that the experimental group and the control group are comparable

false

If an association is found between the incidence of a disease and a certain genetically determined characteristic:

genetic factors are implicated in at least some cases of the disease

In a study of Japanese migrants to the United States, the following standardized mortality ratios (SMRs) were found for disease X: These findings suggest that:

genetic factors are the major determinants of these SMRs

the best index for concluding that an early detection program for breast cancer truly improves the natural history of disease, 15 years after its initiation, would be:

improved long-term survival rates for breast cancer patients (adjusted for lead time)

Two thousand people, 1500 women and 500 men, were surveyed for signs and symptoms of rheumatic fever (RA). 50 people met the American Rheumatoid Association diagnostic criteria for RA. 45 of the cases were women.What is the incidence of RA among women in this population?

incidence of RA among women in this population cannot be determined by the information provided

"When the incidence rate of a disease in the presence of two or more risk factors differs from the incidence rate expected to result from their individual effects" is the definition of:

interaction

Which of the following is a measure of the prognosis of a disease?

median survival time

A new screening program was instituted in a certain country. the program used a screening test that is effective in detecting cancer Z at an early stage. assume that there is no effective treatment for this type of cancer and, therefore, that the program results in no change in the usual course of the disease. Assume also that the rates noted are calculated from all known cases of cancer Z and that there were no changes in the quality of death certification of this disease what will happen to the apparent mortality rate from cancer Z in the country as a result of the program?

mortality rate will remain constant

One of the main reasons that it took so long for the causal relationship between helicobactor infection and stomach ulcers to be recognized as valid is because:

most medical professionals firmly believed that stress played an important causal role in ulcer disease.

In 1974, serum samples and information on demographic characteristics and smoking were collected in a community survey. In 1986, females with newly diagnosed breast cancer who participated in the survey were identified. Each was matched by race and age to a female without the disease who had also participated in the survey. The association of smoking and breast cancer was examined using the data collected in 1974. The above study is best described as a:

nested case-control study

A case-control study was done to investigate the relationship between alcohol consumption and esophageal cancer. 200 subjects with esophageal cancer cases and 775 controls without cancer were entered into the study. The exposure of interest was heavy alcohol consumption, which was defined as 80 grams or more per day. Below is the contingency table that displays the data from this study. The appropriate measure of association for this study design is:

odds ratio

A history of active exercise was compared for women with hip fracture and unmatched controls. Active exercise in the previous two years was reported by 31% of the cases and 46% of the controls. What is the association between hip fracture and active exercise?

odds ratio=0.53

Previous reports offer limited support for an association between cigarette smoking and Hodgkin's disease. In a recent study investigators examined the relationship between cigarette smoking and risk of Hodgkin's disease by recruiting 343 men from eight US population-based registries diagnosed with Hodgkin's disease between 1984 and 1988. 1,910 men without Hodgkin's disease were recruited through random digit dialing. 237 of the men with Hodgkin's disease and 998 of the men without Hodgkin's disease were found to be current smokers. Calculate the measure of association. The correct measure of association for this study is:

odds ratio=2.0

The advantages of targeting disease prevention programs to populations at high risk for the disease include all except

possible stigmatization of the group targeted

A new screening program was instituted in a certain country. the program used a screening test that is effective in detecting cancer Z at an early stage. assume that there is no effective treatment for this type of cancer and, therefore, that the program results in no change in the usual course of the disease. Assume also that the rates noted are calculated from all known cases of cancer Z and that there were no changes in the quality of death certification of this disease what will happen to the apparent prevalence rate of cancer Z in the country during the first year of this program?

prevalence rate will increase

John Snow made a spot map of the mortality from cholera in London during the 1854 epidemic. He concluded that the source of the infection was contaminated water from the Broad Street well. He convinced the city health authorities to remove the pump handle from this well. This is an example of:

primary prevention

Children with a negative history for mumps were randomly allocated to one of two groups. The first group received live attenuated mumps virus vaccine and the other group received a suitably disguised placebo. An outbreak of mumps occurred a few months later. After it had subsided, mumps attack rates were computed for the two groups. Classify the study as to the following:

randomized clinical trial

which of the following is not a possible outcome measure that could be used as an indicator of the benefit of screening programs aimed at early detection of disease?

reduction of incidence in the population screened

Disease-specific mortality rates for a given disease can give a good picture of the incidence of a disease when:

the case-fatality rate is high and the disease duration is short

The Royal College of General Practitioners designed and carried out a cohort study of the adverse effects of oral contraceptives (OCs). In assessing the risk of stroke related to OCs, all of the following were important methodologic considerations in designing the study EXCEPT:

the difficulty of finding enough women with strokes at the beginning of the study in whom past use of OCs could be determined

A randomized clinical trial is only ethical if it is not known whether the experimental treatment is better than the standard treatment

true

A type II error occurs when the study concludes erroneously that there is no difference between the outcome of the experimental group and the control group

true

Both an odds ratio and a relative risk can be calculated from the data of a cohort study

true

Diseases can be transmitted directly or can be transmitted indirectly by a common vehicle or by a vector.

true

Edward Jenner prevented smallpox in suceptible individuals by innoculating them with infectious material from persons suffering from cowpox

true

In a steady state situation in which rates are not changing and in-migration equals out-migration, the following equation applies: prevalence = incidence x duration of illness

true

In order for a randomized trial to have enough power to distingush that there is a difference in outcomes between the experimental group and the control group, a determination must be made as to the minimum number of patients that need to be recruited for the study.

true

Studying high risk groups over time can help to elucidate the etiology of the disease

true

Subclinical disease can be an important factor in the transmission of disease

true

The crude mortality rate for a specific disease in a population reflects the risk of dying from that disease in that population.

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