NR 503 Midterm Exam and Final Exam Study Guide (Latest): Population Health, Epidemiology & Statistical Principles: Chamberlain College of Nursing

NR 503 Midterm Exam and Final Exam Study Guide / NR503 Epidemiology Exam Study Guide (Latest): Population Health, Epidemiology & Statistical Principles: Chamberlain College of Nursing Question 1 Which of the following is a condition which may occur during the incubation period? • Onset of clinical illness • Receipt of infection • Signs and symptoms of disease • Transmission of infection • Isolation of disease carrier through quarantine Question 2 Chicken pox is a highly communicable disease. It may be transmitted by direct contact with a person infected with the varicella-zoster virus (VZV). The typical incubation time is between 10 to 20 days. A boy started school 2 weeks after showing symptoms of chicken pox including mild fever, skin rash, and fluid-filled blisters. One month after the boy returned to school, none of his classmates had been infected by VZV. The main reason was: • Herd immunity • All had been immunized prior to the school year • Contact was after infectious period • Subclinical infections were not yet detected • Disease was endemic in the class Question 3 The ability of a single person to remain free of clinical illness following exposure to an infectious agent is known as: • Hygiene • Vaccination • Herd immunity • Immunity • Latency Question 4 Which of the following is characteristic of a single-exposure, common-vehicle outbreak? • Long latency period before many illnesses develop • There is an exponential increase in secondary cases following initial exposures • Cases include only those who have been exposed to sick persons • The epidemic curve has a normal distribution when plotted against the logarithm of time • Wide range in incubation times for sick individuals Question 5 What is the diarrhea attack rate in persons who ate both ice cream and pizza? • 39/52 • 21/70 • 39/67 • 51/67 • none of the above Question 6 What is the overall attack rate in persons who did not eat ice cream? • 30% • 33% • 35% • 44% • 58%   Question 7 Which of the food items (or combination of items) is most likely to be the infective item(s)? • Pizza only • Ice cream only • Neither pizza nor ice cream • Both pizza and ice cream • Cannot be assumed from the data shown Question 8 Which of the following reasons can explain why a person who did not consume the infective food item got sick? • They were directly exposed to persons who did eat the infective food item • Diarrhea is a general symptom consistent with a number of illnesses • There may have been an inaccurate recall of which foods were eaten • All of the above • None of the above Question 9 An outbreak of gastroenteritis occurred at a boarding school with a student enrollment of 846. Fifty-seven students reported symptoms including vomiting, diarrhea, nausea, and low-grade fever between 10 p.m. on September 24 and 8 p.m. on September 25. The ill students lived in dormitories that housed 723 of the students. The table below provides information on the number of students per type of residence and the number reporting illnesses consistent with the described symptoms and onset time. Calculate the attack rate among all students at the boarding school. Question 10 An outbreak of gastroenteritis occurred at a boarding school with a student enrollment of 846. Fifty-seven students reported symptoms including vomiting, diarrhea, nausea, and low-grade fever between 10 p.m. on September 24 and 8 p.m. on September 25. The ill students lived in dormitories that housed 723 of the students. The table below provides information on the number of students per type of residence and the number reporting illnesses consistent with the described symptoms and onset time. Calculate the attack rates for boys and girls separately. Question 11 An outbreak of gastroenteritis occurred at a boarding school with a student enrollment of 846. Fifty-seven students reported symptoms including vomiting, diarrhea, nausea, and low-grade fever between 10 p.m. on September 24 and 8 p.m. on September 25. The ill students lived in dormitories that housed 723 of the students. The table below provides information on the number of students per type of residence and the number reporting illnesses consistent with the described symptoms and onset time. What is the proportion of total cases occurring in boys? Question 12 An outbreak of gastroenteritis occurred at a boarding school with a student enrollment of 846. Fifty-seven students reported symptoms including vomiting, diarrhea, nausea, and low-grade fever between 10 p.m. on September 24 and 8 p.m. on September 25. The ill students lived in dormitories that housed 723 of the students. The table below provides information on the number of students per type of residence and the number reporting illnesses consistent with the described symptoms and onset time. What is the proportion of total cases occurring in students who live in dormitories? Question 13 An outbreak of gastroenteritis occurred at a boarding school with a student enrollment of 846. Fifty-seven students reported symptoms including vomiting, diarrhea, nausea, and low-grade fever between 10 p.m. on September 24 and 8 p.m. on September 25. The ill students lived in dormitories that housed 723 of the students. The table below provides information on the number of students per type of residence and the number reporting illnesses consistent with the described symptoms and onset time. Which proportion is more informative for the purpose of the outbreak investigation? Question 14 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? Question 15 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 incidence of CHD during the 5-year study? Question 16 Which of the following are examples of a population prevalence rate? • The number of ear infections suffered by 3-year-old children in March, 2006 • The number of persons with hypertension per 100,000 population • The number of cases of skin cancer diagnosed in a dermatology clinic • b and c • All of the above Question 17 What would be the effect on age-specific incidence rates of uterine cancer if women with hysterectomies were excluded from the denominator of incidence calculations assuming that most women who have had hysterectomies are older than 50 years of age. • The rates in all age groups would remain the same. • Only rates in women older than 50 years of age would tend to decrease. • Rates in women younger than 50 years would increase compared to women older than 50 years of age. • Rates would increase in women older than 50 years of age but may decrease in younger women as they get older. • It cannot be determined whether the rates would increase or decrease. Question 18 A survey was conducted among 1,000 randomly sampled adult males in the United States in 2005. The results from this survey are shown below. The researchers stated that there was a doubling of risk of hypertension in each age group younger than 60 years of age. You conclude that the researchers’ interpretation: • Is correct • Is incorrect because prevalence rates are estimated • Is incorrect because it was based on proportions of the population sample • Is incorrect because incidence rates do not describe risk • Is incorrect because the calculations do not include adult females Question 19 The incidence and prevalence rates of a chronic childhood illness for a specific community are given below. Based on the data, which of the following interpretations best describes disease X? • The duration of disease is becoming shorter. • The duration of disease is becoming longer. • The case-fatality rate of this disease is decreasing. • Efforts to prevent new cases of this disease are becoming more successful. • The risk of the disease has decreased over the past 20 years. Question 20 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? Question 21 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. Has the risk of tuberculosis increased or decreased during 2003? Question 22 Which of the following is an advantage of active surveillance? • Requires less project staff • Is relatively inexpensive to employ • More accurate due to reduced reporting burden for health care providers • Relies on different disease definitions to account for all cases • Reporting systems can be developed quickly Question 23 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 monthly incidence rate of active cases of influenza for the 3-month period was: • 4 per 1,000 population • 17 per 1,000 population • 20 per 1,000 population • 39 per 1,000 population • 130 per 1,000 population Question 24 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: • 10 per 1,000 population • 14 per 1,000 population • 17.5 per 1,000 population • 20 per 1,000 population • Cannot be calculated as there is no information on duration Question 25 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. What can be inferred about influenza cases occurring in the city? • Active surveillance would enable better prevention of influenza • The incidence rate would decrease if active surveillance were employed • The average duration of influenza is approximately 1 month • The actual number of influenza cases occurring in the population is less since hospitals and private physicians may be reporting the same patients. • The prevalence rate should be higher since it should be calculated based on all cases of influenza occurring from January 1 through March 30, 2005. Question 26 A study found that adults older than age 50 had a higher prevalence of pneumonia than those who were younger than age 50. Which of the following is consistent with this finding? • Younger adults have a higher incidence of pneumonia • Older adults have a higher case-fatality rate from pneumonia • Younger adults with pneumonia are more likely to report being ill than older persons • Incidence rates do not vary by age, but older adults have pneumonia for a longer duration compared to younger adults • None of the above Question 27 Which of the following statements are true? More than one answer may be correct. • Prevalence rates are always larger than incidence rates • In a steady state, the prevalence of disease is equal to the attack rate • Diagnostic criteria rarely impact estimates of disease prevalence and incidence • Prevalence rates are useful for public health planning • Incidence rates can be used to estimate prevalence when the mean duration of the disease is known Question 28 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? • Incidence is higher and prevalence is higher than in 1999 • Incidence is higher in 2000 but prevalence remains the same • Incidence is the same in 2000 but prevalence is higher than in 1999 • Both incidence and prevalence remain the same as in 1999 • Incidence is the same in 2000 but prevalence is lower than in 1999 Question 29 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. Which statement is true concerning the duration of the disease after the development of the lab test? • Mean duration of a case of the disease is shorter in 2000 • Mean duration of a case of the disease is the same in 2000 • Mean duration of a case of the disease is longer in 2000 • No inference about mean duration can be made since the lab test has only been available for 1 year Question 30 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. Which statement is true concerning the disease-specific mortality rate after the development of the lab test? • The mortality rate for the disease is decreased in 2000 • The mortality rate for the disease is the same in 2000 • The mortality rate for the disease is increased in 2000 • No inference about the mortality rate can be made since the lab test has only been available for 1 year Question 31 In a coastal area of a country in which a tsunami struck, there were 100,000 deaths in a population of 2.4 million for the year ending December 31, 2005. What was the all-cause crude mortality rate per 1,000 persons during 2005? Question 32 In an industrialized nation, there were 192 deaths due to lung diseases in miners ages 20 to 64 years. The expected number of deaths in this occupational group, based on age-specific death rates for lung diseases in all males ages 20 to 64 years, was 238 during 1990. What was the standardized mortality ratio (SMR) for lung diseases in miners? Question 33 In 2001, a state enacted a law that required the use of safety seats for all children under 7 years of age and mandatory seatbelt use for all persons. The table below lists the number of deaths due to motor vehicle accidents (MVAs) and the total population by age in 2000 (before the law) and in 2005 (4 years after the law was enacted). What is the age-specific mortality rate due to MVAs for children ages 0 to 18 years in 2000? • 1.8 per 1,000 • 2.9 per 1,000 • 4.0 per 1,000 • 6.1 per 1,000 • Cannot be calculated from information given Question 34 In 2001, a state enacted a law that required the use of safety seats for all children under 7 years of age and mandatory seatbelt use for all persons. The table below lists the number of deaths due to motor vehicle accidents (MVAs) and the total population by age in 2000 (before the law) and in 2005 (4 years after the law was enacted). Using the pooled total of the 2000 and 2005 populations as the standard rate, calculate the age-adjusted mortality rate due to MVAs in 2005. Question 35 In 2001, a state enacted a law that required the use of safety seats for all children under 7 years of age and mandatory seatbelt use for all persons. The table below lists the number of deaths due to motor vehicle accidents (MVAs) and the total population by age in 2000 (before the law) and in 2005 (4 years after the law was enacted). Based on the information in the table, it was reported that there was an increased risk of death due to MVAs in the state after the law was passed. These conclusions are: • Correct, because there were 1.8 times as many MVA deaths in 2005 as in 2000 • Correct, because for each age group, the mortality rates were higher in 2005 than they were in 2000 • Correct, because both the total and the age-adjusted mortality rates are higher in 2005 than in 2000 • Incorrect, because the age-adjusted mortality rate due to MVA is actually lower in 2005 than in 2000 • Incorrect, because the overall mortality rate is the same in both years Question 36 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 rates and mortality rates will be similar • Mortality rates will be much higher than incidence rates • Incidence rates will be much higher than mortality rates • Incidence rates will be unrelated to mortality rates • None of the above Question 37 The following table gives the mean annual age-specific mortality rates from measles during the first 25 years of life in successive 5-year periods. You may assume that the population is in a steady state (i.e., migrations out are equal to migrations in). The age-specific mortality rates for the cohort born in are: • 2.4  2.8  1.7  1.5  0.4 • 2.9  3.7  2.8  2.0  0.6 • 2.9  2.4  1.7  1.3  0.8 • 2.4  3.3  2.0  0.6  0.1 • 1.7  2.8  2.2  1.1  0.2 Question 38 The following table gives the mean annual age-specific mortality rates from measles during the first 25 years of life in successive 5-year periods. You may assume that the population is in a steady state (i.e., migrations out are equal to migrations in). Based on the information above, one may conclude: • Age-specific mortality rates for measles decreased for the period 1910–1914 to 1925–1929 • Age-specific mortality rates for measles increased for the period 1910–1914 to 1925–1929 • The case-fatality rate decreased for the period 1910–1914 to 1935–1939 • Children born in 1910–1914 had the highest rate of death in all periods • Children ages 5 to 9 had the highest rate of death in all periods Question 39 Which of the following characteristics indicate that mortality rates provide a reliable estimate of disease incidence? More than one answer may be correct. • Case-fatality rate is low • The case-fatality rate is high • The duration of disease is short • The prevalence of disease is greater than 5% • The proportionate mortality is high Question 40 Which of the following statements are true? More than one answer may be correct. • A mortality rate is an example of an incidence rate • Death certificate data are generally valid regardless of the cause of death • Type of disease is the most important predictor of mortality • Changing diagnostic criteria does not affect estimates of prevalence and incidence • The case-fatality rate is calculated based on the entire population at risk Question 41 Among those who are 25 years of age, those who have been driving less than 5 years had 13,700 motor vehicle accidents in 1 year, while those who had been driving for more than 5 years had 21,680 motor vehicle accidents during the same time period. It was concluded from these data that 25-year-olds with more driving experience have increased accidents compared to those who started driving later. This conclusion is: • Correct based on the data • Incorrect because rates are not reported • Incorrect because prevalence estimates are given when incidence rates should be reported • Incorrect because there are no comparison groups identified • Both b and d are correct Question 42 For a disease such as liver cancer, which is highly fatal and of short duration, which of the following statements is true? Choose the best answer. • Mortality rates will be much higher than incidence rates • Mortality rates will be much higher than prevalence rates • Incidence rates will be much higher than mortality rates • Case-fatality rates will be equal to mortality rates • Incidence rates will be equal to mortality rates Question 43 The prevalence rate of a disease is two times greater in women than in men, but the incidence rates are the same in men and women. Which of the following statements may explain this situation? • The duration of disease is shorter in women • Men are at greater risk for developing the disease • The case-fatality rate is lower for women • The age-adjusted mortality rate will be higher for women • The proportionate mortality rate for the disease is higher for men Question 44 The table below describes the number of illnesses and deaths caused by plague in four communities. The case-fatality rate associated with plague is lowest in which community? • Community A • Community B • Community C • Community D Question 45 The table below describes the number of illnesses and deaths caused by plague in four communities. The proportionate mortality ratio associated with plague is lowest in which community? • Community A • Community B • Community C • Community D Question 1 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 that of HT-Aware • The specificity of HT-Warning is greater than that of HT-Aware • The number of false positives is greater with HT-Warning than with HT-Aware • The number of false negatives is greater with HT-Warning than with HT-Aware • The sensitivity and specificity are the same for both tests Question 2 A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. The prevalence of myopia in this population is known to be 15%. The sensitivity of the examination is 60% and its specificity is 80%. All children labeled as “positive” (i.e., suspected of having myopia) by the school nurse are sent for examination by an optometrist. The sensitivity of the optometrist’s examination is 98% and its specificity is 90%. How many children are labeled “positive” by the school nurse? Question 3 A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. The prevalence of myopia in this population is known to be 15%. The sensitivity of the examination is 60% and its specificity is 80%. All children labeled as “positive” (i.e., suspected of having myopia) by the school nurse are sent for examination by an optometrist. The sensitivity of the optometrist’s examination is 98% and its specificity is 90%. What is the positive predictive value (PPV) of the school nurse’s exam? Question 4 A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. The prevalence of myopia in this population is known to be 15%. The sensitivity of the examination is 60% and its specificity is 80%. All children labeled as “positive” (i.e., suspected of having myopia) by the school nurse are sent for examination by an optometrist. The sensitivity of the optometrist’s examination is 98% and its specificity is 90%. How many children will be labeled myopic following the optometrist’s exam? Question 5 A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. The prevalence of myopia in this population is known to be 15%. The sensitivity of the examination is 60% and its specificity is 80%. All children labeled as “positive” (i.e., suspected of having myopia) by the school nurse are sent for examination by an optometrist. The sensitivity of the optometrist’s examination is 98% and its specificity is 90%. What is the positive predictive value (PPV) of the optometrist’s exam? Question 6 A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. The prevalence of myopia in this population is known to be 15%. The sensitivity of the examination is 60% and its specificity is 80%. All children labeled as “positive” (i.e., suspected of having myopia) by the school nurse are sent for examination by an optometrist. The sensitivity of the optometrist’s examination is 98% and its specificity is 90%. What is the negative predictive value (NPV) of the optometrist’s exam? Question 7 A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. The prevalence of myopia in this population is known to be 15%. The sensitivity of the examination is 60% and its specificity is 80%. All children labeled as “positive” (i.e., suspected of having myopia) by the school nurse are sent for examination by an optometrist. The sensitivity of the optometrist’s examination is 98% and its specificity is 90%. What is the overall sensitivity of the sequential examinations? Question 8 A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. The prevalence of myopia in this population is known to be 15%. The sensitivity of the examination is 60% and its specificity is 80%. All children labeled as “positive” (i.e., suspected of having myopia) by the school nurse are sent for examination by an optometrist. The sensitivity of the optometrist’s examination is 98% and its specificity is 90%. What is the overall specificity of the sequential examinations? Question 9 A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. The prevalence of myopia in this population is known to be 15%. The sensitivity of the examination is 60% and its specificity is 80%. All children labeled as “positive” (i.e., suspected of having myopia) by the school nurse are sent for examination by an optometrist. The sensitivity of the optometrist’s examination is 98% and its specificity is 90%. What would be the positive predictive value (PPV) of the exam for myopia if the optometrist tested all 1,000 children? Question 10 Which of the following improves the reliability of diabetes screening tests? • Having the same lab analyze all samples • Taking more than one sample for each subject and averaging the results • Insuring that the instrument is standardized before each sample is analyzed • a and c only • All of the above Question 11 A prostate specific antigen (PSA) test is a quick screening test for prostate cancer. A researcher wants to evaluate it using two groups. Group A consists of 1,500 men who had biopsy-proven adenocarcinoma of the prostate while group B consists of 3,000 age- and race-matched men all of whom showed no cancer at biopsy. The results of the PSA screening test in each group is shown in the table. What is the sensitivity of the PSA screening test in the combined groups?   Question 12 A prostate specific antigen (PSA) test is a quick screening test for prostate cancer. A researcher wants to evaluate it using two groups. Group A consists of 1,500 men who had biopsy-proven adenocarcinoma of the prostate while group B consists of 3,000 age- and race-matched men all of whom showed no cancer at biopsy. The results of the PSA screening test in each group is shown in the table. What is the specificity of the screening test in the combined groups? Question 13 A prostate specific antigen (PSA) test is a quick screening test for prostate cancer. A researcher wants to evaluate it using two groups. Group A consists of 1,500 men who had biopsy-proven adenocarcinoma of the prostate while group B consists of 3,000 age- and race-matched men all of whom showed no cancer at biopsy. The results of the PSA screening test in each group is shown in the table. What is the positive predictive value (PPV) of the screening test in the combined groups?   Question 14 A prostate specific antigen (PSA) test is a quick screening test for prostate cancer. A researcher wants to evaluate it using two groups. Group A consists of 1,500 men who had biopsy-proven adenocarcinoma of the prostate while group B consists of 3,000 age- and race-matched men all of whom showed no cancer at biopsy. The results of the PSA screening test in each group is shown in the table. The PSA screening test is used in the same way in two equal-sized populations of men living in different areas of the United States, but the proportion of false positives among those who have a positive PSA test in the first population is lower than that among those who have a positive PSA test in the second population. What is the likely explanation for this finding? • It is impossible to determine what caused the difference • The prevalence of disease is higher in the first population • The specificity of the test is lower in the first population • The specificity of the test is higher in the first population • The prevalence of the disease is lower in the first population Question 15 Test A has a sensitivity of 95% and a specificity of 90%. 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 the tests? • The net sensitivity will be increased if Test B is given first • The total number of false positives found by both tests is decreased if Test B is given first • The net specificity will be decreased if Test B is given first • The total number of false negatives found by both tests is decreased if Test B is given first • There is no good reason to change the order of the tests Question 16 Two neurologists, Drs. J and K, independently examined 70 magnetic resonance images (MRIs) for evidence of brain tumors. As shown in the table below, the neurologists read each MRI as either “positive” or “negative” for brain tumors. Based on the above information, the overall percent agreement between the two doctors including all observations is: • 37.1% • 62.9% • 65.0% • 68.4% • 84.6% Question 17 Two neurologists, Drs. J and K, independently examined 70 magnetic resonance images (MRIs) for evidence of brain tumors. As shown in the table below, the neurologists read each MRI as either “positive” or “negative” for brain tumors. What is the estimate of kappa for the reliability of the two doctors’ test results? • 10.1% • 24.9% • 50.6% • 57.4% • 68.4%   Question 18 This table represents the results of coronary magnetic resonance (CMR) angiography compared to x-ray angiography (the gold standard in diagnosis of coronary artery disease) in a high-risk population of patients scheduled to undergo x-ray angiography for suspected coronary artery disease. In the general population, the prevalence of coronary artery disease is apporximately 6%. Assuming that this sample of patients is representative of the general population, the sensitivity of the CMR test in the general population would be approximately: • Less than 75% • Between 75% and 85% • Between 85% and 90% • Between 90% and 95% • Greater than 95% Question 19 This table represents the results of coronary magnetic resonance (CMR) angiography compared to x-ray angiography (the gold standard in diagnosis of coronary artery disease) in a high-risk population of patients scheduled to undergo x-ray angiography for suspected coronary artery disease. After reviewing the results of the test comparison, an epidemiologist decides that the specificity of the test is too low. Using the same CMR images, he raises the cutoff value for a positive test to increase the specificity. What is the likely effect on the sensitivity? • Sensitivity will increase • Sensitivity will decrease • There will be no effect because the two characteristics are unrelated • The effect cannot be predicted as it will depend on the prevalence rate • Sensitivity will be higher if the positive predictive value is increased Question 20 In comparing the mammography readings of two technicians who evaluated the same set of 600 mammograms for presence of breast cancer from a generally representative sample of women from the population, • Agreement regarding negative or normal mammograms is likely to be low • The kappa statistic measures agreement due to chance only • Overall percent agreement calculated for both readers may conceal significant disagreements regarding positive tests • A kappa of 0.9 would be unsatisfactory • A kappa of 0.6 represents poor agreement Question 21 In a country with a population of 16 million people, 175,000 deaths occurred during the year ending December 31, 2005. These included 45,000 deaths from tuberculosis (TB) in 135,000 persons who were sick with TB. Assume that the population remained constant throughout the year. What was the annual mortality rate for the country during 2005? Question 22 In a country with a population of 16 million people, 175,000 deaths occurred during the year ending December 31, 2005. These included 45,000 deaths from tuberculosis (TB) in 135,000 persons who were sick with TB. Assume that the population remained constant throughout the year. What was the case-fatality rate (CFR) from TB during 2005? Question 23 In a country with a population of 16 million people, 175,000 deaths occurred during the year ending December 31, 2005. These included 45,000 deaths from tuberculosis (TB) in 135,000 persons who were sick with TB. Assume that the population remained constant throughout the year. What is the proportionate mortality ratio (PMR) for TB during 2005? Question 24 In a country with a population of 16 million people, 175,000 deaths occurred during the year ending December 31, 2005. These included 45,000 deaths from tuberculosis (TB) in 135,000 persons who were sick with TB. Assume that the population remained constant throughout the year. Not all 135,000 cases of TB were contracted during 2005. Which of the following statements is true? • The case-fatality rate provides a reasonable estimate of incidence • The prevalence of TB for 2005 is equal to the denominator of the case-fatality rate • The duration of TB is brief • All of the above • None of the above Question 25 Which of the following statements pertains to relative survival? • Refers to survival of first-degree relatives • Is equal to the case-fatality rate • Is generally closer to observed survival rates in younger age groups • Is generally closer to observed survival rates in older age groups • Provides an estimate of proportionate mortality Question 26 What was the probability of surviving the second year given survival to the end of the first year?   Question 27 What was the cumulative probability of surviving after only 2 years of follow-up? Question 28 An important assumption in this type of analysis is that: • No change has occurred in the effectiveness of treatment during the 3-year period • Treatment has improved during the period of the study • Persons lost to follow-up are counted in the table • The data are age-adjusted • Both a and c Question 29 Complete the table. What is the probability that a person enrolled in the study will survive to the end of the third year?   Question 30 Before reporting the results of this survival analysis, the investigators compared baseline characteristics of the 38 people who withdrew from the study before its end to those who had complete follow-up. This was done for which of the following reasons: • To test whether randomization was successful • To check for changes in treatment • To check whether those remaining in the study represent the total study population • To check whether the survival estimate of those remaining in the study is the same as the general population • To check that the survival estimate for those lost to follow-up is the same as the general population Question 31 Which of the following is a key assumption involved in the use of life-table analysis? • The risk of disease does not change within each interval over the period of observation • There are no losses to follow-up in the study population • The frequency of exposure is similar in treatment and comparison groups • The disease is common • The study subjects are representative of the population from which they were drawn Question 32 Which of the following is a measure of disease prognosis? • Prevalence • Median survival time • Age-adjusted mortality rates • Standardized mortality ratio • Proportionate mortality ratio Question 33 In 2003, Sudden Acute Respiratory Syndrome (SARS) appeared in several countries, mainly in Asia. The disease was determined to have been caused by a virus that could be spread from person –to person from the index case occurring in mainland China. This table reflects the total number of reported cases of SARS and deaths among those cases as best as can be determined. What is the overall case-fatality rate for the worldwide epidemic of SARS? • 9.5% • 12.4% • 16.0% • Cannot be determined as the data are not age-adjusted • Cannot be determined as the total number of all deaths is not known Question 34 In 2003, Sudden Acute Respiratory Syndrome (SARS) appeared in several countries, mainly in Asia. The disease was determined to have been caused by a virus that could be spread from person –to person from the index case occurring in mainland China. This table reflects the total number of reported cases of SARS and deaths among those cases as best as can be determined. Based on the table, we can conclude that the case-fatality rate (CFR) in Vietnam: • Is the same as the case-fatality rate in Singapore • Is twice as great as the case-fatality rate in Singapore • Is almost one half that of the case-fatality rate in Singapore • Cannot be determined because the data are not age-adjusted • Depends on the number of secondary cases Question 35 In 2003, Sudden Acute Respiratory Syndrome (SARS) appeared in several countries, mainly in Asia. The disease was determined to have been caused by a virus that could be spread from person –to person from the index case occurring in mainland China. This table reflects the total number of reported cases of SARS and deaths among those cases as best as can be determined. Following a revision in the case definition, more persons were found to have suffered from an infection with the SARS virus. The inclusion of these cases, almost all asymptomatic, did not impact the total number of SARS fatalities. What happened to the case-fatality rate (CFR) following this reclassification? • It remained the same • It was increased • It was decreased • It cannot be determined without knowing the number of new cases • It cannot be determined without age-adjustment Question 36 What is the probability of surviving the second year of the study given that a person survived the first year? Question 37 For all people in the study, what is the probability of surviving to the end of the second year? Question 38 What is the probability chance of surviving 3 years after diagnosis? Question 39 What is the total number of person-years of follow-up for patients in the study assuming a median survival time of one half of the year for all persons dying during an interval and an observation time of one half of the year for all persons withdrawing from the study? Question 40 Before reporting the results of this survival analysis, the investigators compared baseline characteristics of the 44 people who withdrew from the study before its end to those who had complete follow-up. This was done: • To test whether randomization produced similar groups • To check for changes in prognosis • To check whether those withdrawing from the study are similar to persons remaining in the study • To check whether the outcome of those remaining in the study are the same as the underlying population • To check for confounders in the exposed and nonexposed group Question 1 Which of the following statements best describe efficacy? • It is an estimate of the benefit of treatment under ideal conditions • It is an estimate of the benefit of treatment under routine conditions • It is an estimate of the reduction of disease in treated groups • It is an estimate of the reduction of disease in the population • It depends on the prevalence of disease Question 2 A study is conducted for a pharmaceutical agent that has shown promise for reducing heart disease among women. In order to more fully test the agent, an additional study is done restricting the participants to be randomized to those who have a history of hypertension. Which of the following advantages cannot be claimed by the researchers? • Power of the study is increased • Potential benefits in high-risk populations are increased • Validity of the study is increased by focus on a homogenous population • The generalizability of the study is increased • The overall cost of the study is decreased Question 3 A new drug treatment for cardiac thrombus claims to have a higher success rate than the current drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days after treatment. 168 patients who require treatment for cardiac thrombi are randomized after agreeing to participate in a trial of the new drug. The researchers were interested in whether the new drug reduced the need for blood transfusions due to internal hemorrhage compared to the current treatment. The following table summarizes the results of her study: What is the incidence of needing a blood transfusion in the group of persons who were randomized to the new drug treatment? • 31.0% • 41.1% • 51.2% • 62.3% • Incidence cannot be calculated with the information in this table Question 4 A new drug treatment for cardiac thrombus claims to have a higher success rate than the current drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days after treatment. 168 patients who require treatment for cardiac thrombi are randomized after agreeing to participate in a trial of the new drug. The researchers were interested in whether the new drug reduced the need for blood transfusions due to internal hemorrhage compared to the current treatment. The following table summarizes the results of her study: What is the number of persons who died in hospital in the study? • 7 • 17 • 28 • 35 • The number of deaths cannot be calculated as the death rate has not been age-adjusted Question 5 A new drug treatment for cardiac thrombus claims to have a higher success rate than the current drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days after treatment. 168 patients who require treatment for cardiac thrombi are randomized after agreeing to participate in a trial of the new drug. The researchers were interested in whether the new drug reduced the need for blood transfusions due to internal hemorrhage compared to the current treatment. The following table summarizes the results of her study: What is the main advantage of the randomization of the 168 study participants to one of the two drug treatment groups? • Ensures that the researchers are masked to the treatment group assignment for each participant • Facilitates the age-adjustment of the death rate in each group • Reduces the potential for selection bias in allocation of treatment group • Ensures that the study groups are comparable for characteristics such as age and severity of condition prior to treatment assignment • Ensures that non-compliance will not affect the results Question 6 A new drug treatment for cardiac thrombus claims to have a higher success rate than the current drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days after treatment. 168 patients who require treatment for cardiac thrombi are randomized after agreeing to participate in a trial of the new drug. The researchers were interested in whether the new drug reduced the need for blood transfusions due to internal hemorrhage compared to the current treatment. The following table summarizes the results of her study: The researchers interpret the findings to conclude that the new drug treatment is more likely to result in a blood transfusion and subsequent death. This statement is: • Incorrect as the data do not indicate the death rate among only those receiving a blood transfusion • Incorrect as the number of expected deaths is not known • Incorrect as the cause-specific death rate for internal hemorrhaging is not reported • Incorrect as the duration of time from blood transfusion to death is not reported • Correct Question 7 A randomized, double-blind clinical trial of a varicella vaccine observed an estimated incidence of 25% chickenpox episodes in persons receiving the vaccine, compared to 80% among persons receiving a placebo. The estimated efficacy of the vaccine is: • 55.0% • 65.0% • 68.8% • 71.4% • 80.0% Question 8 A multicenter double-blind randomized study was carried out to compare the effect of drug X with that of a placebo in patients surviving acute myocardial infarction (AMI). Treatment with the drug started 7 days after infarction in 1,884 patients, 52% of all persons who were evaluated for entry into the study. 945 participants were randomized to treatment with drug X while 939 were assigned to the placebo group. Patients were then followed for 12 months for reinfarction. There were 152 deaths in the placebo group and 98 in the group receiving drug X. After entry into the study, patients were first classified into three groups, those who had a previous AMI, those with a first AMI who were at high risk for other cardiovascular diseases such as congestive heart failure, and those with a first AMI who were at low risk for other cardiovascular diseases. Which term best describes the study design? • Cohort study • Randomized clinical trial with crossover design • Randomized clinical trial with factorial design • Randomized clinical trial with stratified randomization • Case study design Question 9 A multicenter double-blind randomized study was carried out to compare the effect of drug X with that of a placebo in patients surviving acute myocardial infarction (AMI). Treatment with the drug started 7 days after infarction in 1,884 patients, 52% of all persons who were evaluated for entry into the study. 945 participants were randomized to treatment with drug X while 939 were assigned to the placebo group. Patients were then followed for 12 months for reinfarction. There were 152 deaths in the placebo group and 98 in the group receiving drug X. After assignment to treatment group, 77% of those in the placebo group were men, while 80% of those in the drug X group were men. Which statement is most likely to be true? • Randomization failed because the percentage of men is different in each group • Randomization failed because the researchers should have made sure that each group had an equal percentage of men • Randomization failed since men are more likely to have a recurrent AMI in the drug X group • Randomization was successful because there are more men in the treatment group • Randomization was successful since the investigators did not alter the selection of participants in either group in order to ensure equal percentages of men Question 10 A multicenter double-blind randomized study was carried out to compare the effect of drug X with that of a placebo in patients surviving acute myocardial infarction (AMI). Treatment with the drug started 7 days after infarction in 1,884 patients, 52% of all persons who were evaluated for entry into the study. 945 participants were randomized to treatment with drug X while 939 were assigned to the placebo group. Patients were then followed for 12 months for reinfarction. There were 152 deaths in the placebo group and 98 in the group receiving drug X. A preliminary analysis was conducted after 6 months and found that 87% of participants in the placebo group and 85% of those in the drug X group had taken more than 90% of their prescribed dosages. Which statement best describes this finding? • Randomization failed to ensure an equal likelihood of compliance with treatment • The characteristics of patients who failed to comply with the treatment dosages should be assessed as they may differ from those who complied • The study will find a decreased effect of AMI prevention in the drug X group since fewer participants complied with the prescribed treatment • The study will find an increased effect of AMI prevention in the placebo group since more participants complied with the prescribed treatment • The researchers should consider a crossover design in order to calibrate the compliance rates between each group Question 11 A multicenter double-blind randomized study was carried out to compare the effect of drug X with that of a placebo in patients surviving acute myocardial infarction (AMI). Treatment with the drug started 7 days after infarction in 1,884 patients, 52% of all persons who were evaluated for entry into the study. 945 participants were randomized to treatment with drug X while 939 were assigned to the placebo group. Patients were then followed for 12 months for reinfarction. There were 152 deaths in the placebo group and 98 in the group receiving drug X. Which of the following statements best describes the reason for conducting the study as a double-blind trial? • The placebo group will not have any reported side effects • The researchers might assign participants with more serious AMIs to the treatment group • Since the outcome studied is death, blinding the participants is unnecessary for this trial • Double blinding ensures that potential biases regarding selection, follow-up, and analysis can be reduced • Double blinding is no longer necessary after randomization is complete since the researchers cannot change the treatment group assignments Question 12 A multicenter double-blind randomized study was carried out to compare the effect of drug X with that of a placebo in patients surviving acute myocardial infarction (AMI). Treatment with the drug started 7 days after infarction in 1,884 patients, 52% of all persons who were evaluated for entry into the study. 945 participants were randomized to treatment with drug X while 939 were assigned to the placebo group. Patients were then followed for 12 months for reinfarction. There were 152 deaths in the placebo group and 98 in the group receiving drug X. The researchers conclude that treatment with drug X reduces mortality in patients who have had an AMI. The researchers are: • Correct because there are a fewer number of deaths in the drug X group • Correct because the rate of death is decreased in the drug X group • Incorrect because non-compliance may have reduced the number of observed deaths in the drug X group compared to the placebo group • Incorrect because randomization was not successful • Incorrect as the results are not generalizable to all patients with AMI since the researchers excluded 48% of the persons evaluated for the study Question 13 The following data come from a study of approaches to smoking cessation. Smokers who want to quit were randomized to one of four groups: control group C who received no intervention assistance, quitting guide group Q who received brochures about how to quit smoking, quitting guide and support group QS who received quitting brochures as well as social support brochures listing benefits of smoking cessation, and telephone support group T who received the brochures and a monthly phone call from a counselor. Participants received mailed surveys at 8, 16, and 24 months after randomization. The results after 2 years are in the table below. What is the overall quit rate after 2 years of follow-up? Question 14 The following data come from a study of approaches to smoking cessation. Smokers who want to quit were randomized to one of four groups: control group C who received no intervention assistance, quitting guide group Q who received brochures about how to quit smoking, quitting guide and support group QS who received quitting brochures as well as social support brochures listing benefits of smoking cessation, and telephone support group T who received the brochures and a monthly phone call from a counselor. Participants received mailed surveys at 8, 16, and 24 months after randomization. The results after 2 years are in the table below. Which group had the least success in terms of quitting smoking? • Group C • Group Q • Group QS • Group T • It cannot be determined since each group had participants with missing outcomes Question 15 The following data come from a study of approaches to smoking cessation. Smokers who want to quit were randomized to one of four groups: control group C who received no intervention assistance, quitting guide group Q who received brochures about how to quit smoking, quitting guide and support group QS who received quitting brochures as well as social support brochures listing benefits of smoking cessation, and telephone support group T who received the brochures and a monthly phone call from a counselor. Participants received mailed surveys at 8, 16, and 24 months after randomization. The results after 2 years are in the table below. What is the main purpose of randomization in this study? • To avoid assigning more persons who have tried and failed to quit in the past to the control group • To blind the researchers to the treatment group assignments • To ensure that rates of smoking cessation will be the same among the groups • To minimize differences in the dropout rate between the groups • To prevent subjects in the control group from reading materials that would help them to quit smoking Question 1 A study is planned to investigate the relationship of factors associated with maternal hypertension and the risk of congenital birth defects in children born to these women. Which of the following would be a reason for using a cohort study design? • The need to obtain data on the incidence of early fetal losses due to congenital birth defects • The low rate of congenital birth defects • The development of pregnancy-related hypertension in asymptomatic women • The consistency of recall of risk factors among women having children with and without congenital birth defects and those having children • Testing hypotheses about several different risk factors for congenital birth defects such as maternal age, diabetes, and previous miscarriage history Question 2 A researcher is interested in the etiology of myocardial infarction (MI) among men between 18 and 40 years of age. Her hypothesis concerns the influence of diets high in fat and subsequent development of MI. What is the best study approach to address this hypothesis? • Case-control study with cases of MI identified post-event and controls sampled from healthy men in the population, then have both groups complete dietary surveys • Case-report study describing the dietary habits in 100 men having an MI • Ecologic study with the rates of MI compared between cities with higher than average dietary fat intakes and cities with lower than average dietary fat intakes • Retrospective cohort study with medical records used to collect information on diet among men with and without an MI • Prospective cohort study identifying a population of men in this age group, administering a dietary survey and classifying men by high and low fat diet, then following both groups for the development of an MI Question 3 Which of the following is an advantage to the conduct of a cohort study? • The study population is the same with regard to the risk factors for disease • The disease under study occurs rarely in the population • The incidence of the disease is high in the nonexposed group • The incidence of the disease is high in the exposed group • The study population includes a high number of undiagnosed, asymptomatic individuals with the disease Question 4 A cohort study is planned to investigate the potential adverse health effects of daily alcohol consumption. In assessing the risk of liver cancer related to alcoholism, which of the following is not an important methodologic consideration? • The need to study a large number of persons for a rare disease outcome • The difficulty of finding enough persons with liver cancer at the beginning of the study in whom alcohol consumption could be determined • The possible bias associated with persons describing alcohol usage • The likelihood that doctors would monitor alcoholics more closely for liver cancers • The possibility that persons would change their alcohol consumption practices during the study period Question 5 Which of the following is not an advantage of a retrospective cohort study? • Allows for the study of many disease outcomes resulting from an exposure • Incidence rates can be calculated • Possible bias due to selection of the cohort is eliminated • Potential recall bias can be minimized • Requires less follow-up time than a prospective cohort study Question 6 In a study of the adverse effects of x-rays among children, a retrospective cohort study was done using records from several large children’s hospitals for the period of 1980 to 1985. 10,000 children were selected as a representative population of ill children seen at the hospitals during that time. Subjects were classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their hospital stay through 2005 for the development of cancer. During the follow-up period, 49 incident cancers occurred in 3,263 children who had received an x-ray, and 47 incident cancers occurred in the 6,737 children who had not received an x-ray during their hospitalization. In this retrospective study, which of the following groups are eligible for selection into the study? • Children receiving x-rays in 1990 • Children receiving x-rays in 1975 • Children receiving x-rays for broken bones in 1983 • Children in the hospital for cancer treatment in 1985 • Children who were treated in private clinics and hospitals in 1981 Question 7 In a study of the adverse effects of x-rays among children, a retrospective cohort study was done using records from several large children’s hospitals for the period of 1980 to 1985. 10,000 children were selected as a representative population of ill children seen at the hospitals during that time. Subjects were classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their hospital stay through 2005 for the development of cancer. During the follow-up period, 49 incident cancers occurred in 3,263 children who had received an x-ray, and 47 incident cancers occurred in the 6,737 children who had not received an x-ray during their hospitalization. What are the rates of cancer incidence in each exposure group? Question 8 In a study of the adverse effects of x-rays among children, a retrospective cohort study was done using records from several large children’s hospitals for the period of 1980 to 1985. 10,000 children were selected as a representative population of ill children seen at the hospitals during that time. Subjects were classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their hospital stay through 2005 for the development of cancer. During the follow-up period, 49 incident cancers occurred in 3,263 children who had received an x-ray, and 47 incident cancers occurred in the 6,737 children who had not received an x-ray during their hospitalization. What is the attributable risk of cancer due to x-ray in this study population? What is the interpretation of this estimate?   Question 9 In a study of the adverse effects of x-rays among children, a retrospective cohort study was done using records from several large children’s hospitals for the period of 1980 to 1985. 10,000 children were selected as a representative population of ill children seen at the hospitals during that time. Subjects were classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their hospital stay through 2005 for the development of cancer. During the follow-up period, 49 incident cancers occurred in 3,263 children who had received an x-ray, and 47 incident cancers occurred in the 6,737 children who had not received an x-ray during their hospitalization. What is the risk ratio for the effect of exposure on the development of cancer in this study? What is the interpretation of this estimated ratio? Question 10 In a study of the adverse effects of x-rays among children, a retrospective cohort study was done using records from several large children’s hospitals for the period of 1980 to 1985. 10,000 children were selected as a representative population of ill children seen at the hospitals during that time. Subjects were classified according to whether or not they received an x-ray during their stay in the hospital and were followed from their hospital stay through 2005 for the development of cancer. During the follow-up period, 49 incident cancers occurred in 3,263 children who had received an x-ray, and 47 incident cancers occurred in the 6,737 children who had not received an x-ray during their hospitalization. Which of the following issues should the investigators consider when interpreting whether a causal association exists between cancer incidence and childhood x-ray? • Some study subjects were treated for cancer starting in 1980 • Some study subjects had parents who were diagnosed with cancer • Some children received x-rays at other hospitals not included in this study • The children were different ages when they were admitted to the hospital • All of the above Question 11 Which of the following may be a factor that would result from the inability to use randomization in a cohort study? • The possibility that a factor which leads to exposure may be causally associated with the disease • The possibility that a higher proportion of exposed persons may be included in the study • The possibility that a higher proportion of nonexposed persons may be included in the study • The study will take longer to conduct if randomization is not used • The possibility that several different types of diseases will develop in the study population Question 12 6,750 people who were free of disease X were enrolled in a cohort study in 1985 and followed with annual exams and interviews through 1995. Exposure to factor A was determined at study enrollment and the participants were followed until 1995 to observe new cases of disease X. Data from the study at the end of follow-up are shown in the following table. What is the incidence rate of disease X among persons exposed to factor A? • 0.04 • 0.19 • 0.25 • 4.00 • 5.17 Question