NR 503 EPIDEMIOLOGY WEEK 8 FINAL EXAM / NR503 EPIDEMIOLOGY WEEK 8 FINAL EXAM: LATEST,CHAMBERLAIN COLLEGE OF NURSING

NR 503 EPIDEMIOLOGY WEEK 8 FINAL EXAM / NR503 EPIDEMIOLOGY WEEK 8 FINAL EXAM: LATEST,CHAMBERLAIN COLLEGE OF NURSINGANR 503 EPIDEMIOLOGY WEEK 8 FINAL EXAM / NR503 EPIDEMIOLOGY WEEK 8 FINAL EXAM 1. Which of the following is a condition which may occur during the incubation period? a. Onset of clinical illness b. Receipt of infection c. Signs & symptoms of disease d. Transmission of infection e. Isolation of disease carrier through quarantine 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, & fluid-filled blisters. One month after the boy returned to school, none of his classmates had been infected by VZV. The main reason was: a. Herd immunity b. All had been immunized prior to the school year c. Contact was after infectious period d. Subclinical infections were not yet detected e. Disease was endemic in the class 3. Which of the following is characteristic of a single-exposure, common-vehicle outbreak? a. Long latency period before many illnesses develop b. There is an exponential increase in secondary cases following initial exposures c. Cases include only those who have been exposed to sick persons d. The epidemic curve has a normal distribution when plotted against the logarithm of time e. Wide range in incubation times for sick individuals 4. What is the diarrhea attack rate in persons who ate both ice cream & pizza? a. 39/52 b. 21/70 c. 39/67 d. 51/67 e. None of the above 5. What is the overall attack rate in persons who did not eat ice cream? a. 30% b. 33% c. 35% d. 44% e. 58% 6. Which of the food items (or combination of items) is most likely to be the infective item(s)? a. Pizza only b. Ice cream only c. Neither pizza or ice cream d. Both pizza & icecream e. Cannot be assumed from the data shown 7. Which of the following reasons can explain why a person who did not consume the infective food item got sick? a. They were directly exposed to persons who did eat the infective food item b. Diarrhea is a general symptom consistent with a number of illnesses c. There may have been an inaccurate recall of which foods were eaten d. All of the above e. None of the above An outbreak of gastroenteritis occurred at a boarding school with a student enrollment of 846. Fifty-seven students reported symptoms including vomiting, diarrhea, nausea, & low-grade fever between 10 p.m. on September 24 & 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 & the number reporting illnesses consistent with the described symptoms & onset time. Calculate the attack rate among all students at the boarding school. 1. Calculate the attack rate among all students at the boarding school. 11. What is the proportion of total cases occurring in boys? 12. What is the proportion of total cases occurring in students who live in dormitories? 13. Which proportion is more informative for the purpose of the outbreak investigation? 14. What was the prevalence of CHD at the initial exam? 15. What was the incidence of CHD during the 5-year study? 16. Which of the following are examples of a population prevalence rate? a. The number of ear infections suffered by 3-year-old children in March, 2006 b. The number of persons with hypertension per 100,000 population c. The number of cases of skin cancer diagnosed in a dermatology clinic d. b & c e. All of the above 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. A. The rates in all age groups would remain the same. B. Only rates in women older than 50 years of age would tend to decrease. C. Rates in women younger than 50 years would increase compared to women older than 50 years of age. D. Rates would increase in women older than 50 years of age but may decrease in younger women as they get older. E. It cannot be determined whether the rates would increase or decrease. 18. 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: a. Is correct b. Is incorrect because prevalence rates are estimated c. Is incorrect because it was based on proportions of the population sample d. Is incorrect because incidence rates do not describe risk e. Is incorrect because the calculations do not include adult females 19. The incidence & 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. 20. What is the incident rate of tuberculosis per 100,000 persons in 2003? Answer: The answer is 29 new cases of tuberculosis per 100,000 persons. This is found by dividing the new cases of tuberculosis by the total population at risk (580/2,000,000) & multiplying this rate by 100,000 to st&ardize the rate. 21. Has the risk of tuberculosis increased or decreased during 2003? 22. Which of the following is an advantage of active surveillance? A. Requires less project staff B. Is relatively inexpensive to employ C. More accurate due to reduced reporting burden for health care providers D. Relies on different disease definitions to account for all cases E. Reporting systems can be developed quickly 23. The population of a city on February 15, 2005, was 36,600. The city has a passive surveillance system that collects hospital & private physician reports of influenza cases every month. During the period between January 1 & 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: a. 4 per 1,000 population b. 17 per 1,000 population c. 20 per 1,000 population d. 39 per 1,000 population e. 130 per 1,000 population 22. 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 23. 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 & 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. 24. 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 25. Which of the following statements are true? More than one answer may be correctPrevalence rates are always larger than incidence rates a. In a steady state, the prevalence of disease is equal to the attack rate b. Diagnostic criteria rarely impact estimates of disease prevalence & incidence c. Prevalence rates are useful for public health planning d. Incidence rates can be used to estimate prevalence when the mean duration of the disease is known 26. A disease has an incidence of 10 per 1,000 persons per year, & 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? a. Incidence is higher & prevalence is higher than in 1999 b. Incidence is higher in 2000 but prevalence remains the same c. Incidence is the same in 2000 but prevalence is higher than in 1999 d. Both incidence & prevalence remain the same as in 1999 e. Incidence is the same in 2000 but prevalence is lower than in 1999 27. 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 28. 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 29. 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? 30. 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 st&ardized mortality ratio (SMR) for lung diseases in miners? 31. In 2001, a state enacted a law that required the use of safety seats for all children under 7 years of age & m&atory seatbelt use for all persons. The table below lists the number of deaths due to motor vehicle accidents (MVAs) & the total population by age in 2000 (before the law) & 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? 32. Using the pooled total of the 2000 & 2005 populations as the st&ard rate, calculate the age-adjusted mortality rate due to MVAs in 2005. . . 33. 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: 34. 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 & 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 . 35. The age-specific mortality rates for the cohort born in are: 36. Based on the information above, one may conclude: • Children ages 5 to 9 had the highest rate of death in all periods 37. Which of the following characteristics indicate that mortality rates provide a reliable estimate of disease incidence? More than one answer may be correct. a. The case-fatality rate is high b. The duration of disease is short 38. Which of the following statements are true? More than one answer may be correct. 39. 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: 40. For a disease such as liver cancer, which is highly fatal & 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 41. The prevalence rate of a disease is two times greater in women than in men, but the incidence rates are the same in men & 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 42. The table below describes the number of illnesses & 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 43. The table below describes the number of illnesses & deaths caused by plague in four communities. The proportionate mortality ratio associated with plague is lowest in which community? Answer: Community D Chapters 5-6 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? a. The sensitivity of HT-Warning is greater than that of HT-Aware b. The specificity of HT-Warning is greater than that of HT-Aware c. The number of false positives is greater with HT-Warning than with HT-Aware d. The number of false negatives is greater with HT-Warning than with HT-Aware e. The sensitivity & specificity are the same for both tests 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% & 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% & its specificity is 90%. How many children are labeled “positive” by the school nurse? 3. What is the positive predictive value (PPV) of the school nurse’s exam? 4. How many children will be labeled myopic following the optometrist’s exam? 5. What is the positive predictive value (PPV) of the optometrist’s exam? 6. What is the negative predictive value (NPV) of the optometrist’s exam? 7. What is the overall sensitivity of the sequential examinations? 8. What is the overall specificity of the sequential examinations? 9. What would be the positive predictive value (PPV) of the exam for myopia if the optometrist tested all 1,000 children? 10. Which of the following improves the reliability of diabetes screening tests? a. Having the same lab analyze all samples b. Taking more than one sample for each subject & averaging the results c. Insuring that the instrument is st&ardized before each sample is analyzed d. a & c only e. All of the above . 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- & 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? 12. What is the specificity of the screening test in the combined groups? 13. What is the positive predictive value (PPV) of the screening test in the combined groups? 14. 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? a. It is impossible to determine what caused the difference b. The prevalence of disease is higher in the first population c. The specificity of the test is lower in the first population d. The specificity of the test is higher in the first population e. The prevalence of the disease is lower in the first population 15. Test A has a sensitivity of 95% & a specificity of 90%. Test B has a sensitivity of 80% & 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? a. The net sensitivity will be increased if Test B is given first b. The total number of false positives found by both tests is decreased if Test B is given first c. The net specificity will be decreased if Test B is given first d. The total number of false negatives found by both tests is decreased if Test B is given first e. There is no good reason to change the order of the tests 16. Two neurologists, Drs. J & 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: 17. What is the estimate of kappa for the reliability of the two doctors’ test results? 18. 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: 19. 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? 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, a. . 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. a. What was the case-fatality rate (CFR) from TB during 2005? b. What is the proportionate mortality ratio (PMR) for TB during 2005? 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. Not all 135,000 cases of TB were contracted during 2005. Which of the following statements is true? a. The case-fatality rate provides a reasonable estimate of incidence b. The prevalence of TB for 2005 is equal to the denominator of the case-fatality rate c. The duration of TB is brief d. All of the above e. None of the above Rationale: Since the duration of TB can be longer than 1 year, neither disease incidence nor prevalence can be validly estimated by mortality indicators. 23. Which of the following statements pertains to relative survival? a. Refers to survival of first-degree relatives b. Is equal to the case-fatality rate c. Is generally closer to observed survival rates in younger age groups d. Is generally closer to observed survival rates in older age groups e. Provides an estimate of proportionate mortality 24. What was the probability of surviving the second year given survival to the end of the first year? 25. What was the cumulative probability of surviving after only 2 years of follow-up? 26. 27. Complete the table. What is the probability that a person enrolled in the study will survive to the end of the third year? 28. 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: 29. Which of the following is a key assumption involved in the use of life-table analysis? a. The risk of disease does not change within each interval over the period of observation b. There are no losses to follow-up in the study population c. The frequency of exposure is similar in treatment & comparison groups d. The disease is common e. The study subjects are representative of the population from which they were drawn 30. Which of the following is a measure of disease prognosis? a. Prevalence b. Median survival time c. Age-adjusted mortality rates d. St&ardized mortality ratio e. Proportionate mortality ratio 31. 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 mainl& China. This table reflects the total number of reported cases of SARS & deaths among those cases as best as can be determined. What is the overall case-fatality rate for the worldwide epidemic of SARS? 32. 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 mainl& China. This table reflects the total number of reported cases of SARS & 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: a. Is the same as the case-fatality rate in Singapore b. Is twice as great as the case-fatality rate in Singapore c. Is almost one half that of the case-fatality rate in Singapore d. Cannot be determined because the data are not age-adjusted e. Depends on the number of secondary cases Rationale: The CFR in Vietnam equals 5 divided by 63, or 7.9%, while that of Singapore equals 15%. This is approximately one half the rate. 33. What happened to the case-fatality rate (CFR) following this reclassification? 34. What is the probability of surviving the second year of the study given that a person survived the first year? 35. For all people in the study, what is the probability of surviving to the end of the second year? 36. What is the probability chance of surviving 3 years after diagnosis? 37. 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 & an observation time of one half of the year for all persons withdrawing from the study? 38. 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: