NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success, Exams of Nursing

Download NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success and more Exams Nursing in PDF only on Docsity! Transmission of infection Immunity The epidemic curve has a normal distribution when plotted against the logarithm of time 39/52 NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Chapters 2-4 Which of the following is a condition which may occur during the incubation period? 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: Contact was after infectious period The ability of a single person to remain free of clinical illness following exposure to an infectious agent is known as: Which of the following is characteristic of a single-exposure, common-vehicle outbreak? What is the diarrhea attack rate in persons who ate both ice cream & pizza? What is the overall attack rate in persons who did not eat ice cream? 33% NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Ice cream only 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) NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Which of the food items (or combination of items) is most likely to be the infective item(s)? Which of the following reasons can explain why a person who did not consume the infective food item got sick? 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. The answer is found by dividing the total number of cases (57) by the total number of students (846). This equals 6.7%. 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 rates for boys & girls separately. For boys, the attack rate includes all cases (40 + 3) divided by the total number of students who are boys (380 + 46). The attack rate is 10.1%. For girls, the attack rate includes all cases (12 + 2) divided by the total number of students who are girls NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success The duration of disease is becoming shorter. More accurate due to reduced reporting burden for health care providers NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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? 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? 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. 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? The risk of tuberculosis has increased over the historic incident rate. This comparison can be made by st&ardizing the historic rate to a rate per 100,000 persons. To do this, multiply the numerator & denominator by 25. Which of the following is an advantage of active surveillance? NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 20 per 1,000 population The average duration of influenza is approximately 1 month 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 NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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: 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 prevalence rate of active influenza as of April 1, 2005, was: 20 per 1,000 population 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. What can be inferred about influenza cases occurring in the city? 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? Incidence rates do not vary by age, but older adults have pneumonia for a longer duration compared to younger a Which of the following statements are true? More than one answer may be correct. A disease has an incidence of 10 per 1,000 persons per year, & 80% of those affected will die within NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Incidence is higher & prevalence is higher than Mean duration of a case of the disease is longer in 2000 The mortality rate for the disease is the same in 2000 NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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 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. Which statement is true concerning the duration of the disease after the development of the lab test? 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. Which statement is true concerning the disease-specific mortality rate after the development of the lab test? 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? The answer is 41.7 per 1,000 persons. The rate is calculated by dividing 100,000 deaths by the population of 2,400,000 persons. To express as a rate per 1,000 persons, the rate is multiplied by 1,000. 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? The answer is 81. The ratio is calculated by dividing 192 observed deaths by the 238 expected deaths for this age group. To express it as an SMR, the ratio is often multiplied by 100. NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success A mortality rate is an example of an incidence rate Incorrect because rates are not reported The case-fatality rate is lower for women Community C NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Which of the following statements are true? More than one answer may be correct. 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: 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. TIhnecipdreevnacleenrcaeterastewoilflabdeiseeqasueailsttowomtiomrteasligtryearatetrei sn women than in men, but the incidence rates are the same in men & women. Which of the following statements may explain this situation? 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? 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? NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success The number of false positives is greater with HT-Warning than with HT-Aware The sensitivity of HT-Warning NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Community D Chapters 5-6 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? is gre 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? There are 150 children with myopia in the school population (15% prevalence among 1,000 children). The school nurse will identify 60% of those who truly have the condition, or 90 cases (60% sensitivity multiplied by 150 myopic children). Further, the school nurse will incorrectly identify 170 false positive cases of myopia among those who do not have the condition (80% specificity multiplied by 850 non- myopic children). The sum of the cases labeled as positive by the school nurse equals 260 children (90 true myopic children plus 170 false positive children). 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%. What is the positive predictive value (PPV) of the school nurse’s exam? The PPV of the school nurse’s exam is equal to the number of true positive cases divided by the total number of those that the school nurse labels as positive. In this exam, the PPV is 34.6% (90 true myopic children divided by 260 children labeled as myopic by the school nurse). A school nurse examined a population of 1,000 children in an attempt to detect nearsightedness. NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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 will be labeled myopic following the optometrist’s exam? Since the optometrist will only test children who have been labeled as myopic by the school nurse, the testing group for this sequential exam is 260 children. The optometrist labels 105 children as myopic. Among the 90 myopic children correctly referred by the school nurse, the optometrist identifies 88 of them as myopic (98% sensitivity multiplied by 90 true cases of myopia). Further, the optometrist will incorrectly identify 17 false positive cases among the 170 children referred by the school nurse who do not have myopia. The sum of the cases labeled as positive by the optometrist equals 105 children (89 true cases plus 17 false positive cases). 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%. What is the positive predictive value (PPV) of the optometrist’s exam? The PPV of the optometrist’s exam is equal to the number of true positive cases divided by the total number that the optometrist labels as positive. The optometrist will only test 260 children referred by the school nurse. Of these children, the optometrist will correctly identify 89 cases of myopia among 105 children labeled as positive for the condition. The PPV equals 83.8% (89 true myopic children divided by 105 children labeled as positive). 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%. What is the negative predictive value (NPV) of the optometrist’s exam? The NPV of the optometrist’s exam is 98.7%. The NPV equals the number of true negative cases divided by all negative cases indicated by the exam. In this instance, the optometrist correctly identifies 153 children as negative for myopia; however, there are 2 false negative cases following the optometrist’s exam (90 true cases referred by the school nurse less the 88 cases detected by the optometrist). The NPV equals 153 divided by 155, or 98.7%. 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% & 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 NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success The prevalence of disease is higher in the first population NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success What is the sensitivity of the PSA screening test in the combined groups? The sensitivity equals the number of true positives detected among all true positives. Since a biopsy is the gold st&ard test for prostate cancer, all 1,500 men in group A are positive for prostate cancer. The PSA test indicated that 1,155 of these men had prostate cancer, a sensitivity of 77%. 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 specificity of the screening test in the combined groups? The specificity equals the number of true negatives detected among all true negatives. Among the 3,000 men who did not have prostate cancer, the test correctly identified 2,760 men as negative for prostate cancer (3,000 minus 240 false positives). This gives a sensitivity of 92%. 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 positive predictive value (PPV) of the screening test in the combined groups? The PPV is 83%. This value is found by dividing 1,155 true positives by the total number of all positives indicated by the PSA test (1,155 plus 24). 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. 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? NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success The total number of false positives found by both tests is decreased if Test B is given first 62.9% 24.9% NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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? 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: 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. What is the estimate of kappa for the reliability of the two doctors’ test results? This table represents the results of coronary magnetic resonance (CMR) angiography compared to x- ray angiography (the gold st&ard in diagnosis of coronary artery disease) in a high-risk population of patients scheduled to undergo x-ray angiography for suspected coronary artery NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Between 90% & 95% Sensitivity will decrease NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success disease. In the general population, the prevalence of coronary artery disease is approximately 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: This table represents the results of coronary magnetic resonance (CMR) angiography compared to x- ray angiography (the gold st&ard 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? 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, Overall percent agreement calculated for both readers may conceal significant disagreements regarding positive 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? The annual mortality rate equals the number of deaths divided by the total population. In this example, 175,000 deaths occurred among 16 million persons. Dividing these numbers & multiplying by 100,000 gives a rate of 1,094 deaths per 100,000 persons, approximately 1% of the population. In a country with a population of 16 million people, 175,000 deaths occurred during the year ending NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success To check whether those remaining in the study represent the total study population The risk of disease does not change within each interval over the period of observation Median survival time 9.5% NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Which of the following is a key assumption involved in the use of life-table analysis? Which of the following is a measure of disease prognosis? 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? 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: Is almost one half that of the case-fatality rate in Singapore NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success It was decreased NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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. 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? What is the probability of surviving the second year of the study given that a person survived the first year? The independent probability of surviving the second year for all persons who survived the first year is found by dividing the number of survivors at the end of the period by the total number present at the beginning of the period. In addition, for those who withdraw during the interval, only 50% of these persons should be counted as being present during the interval. The table should be completed with the following values: Column (B) from top to bottom: 248, 124, 55 Column (E) from top to bottom: 0.410, 0.470, 0.296 Column (F) from top to bottom: 0.590, 0.530, 0.704 Column (G) from top to bottom: 0.590, 0.313, 0.220 Therefore, the second year survival probability among all those surviving in the study past the first year is 53%. The probability of dying during the second year equals the number of deaths during the NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success To check whether those withdrawing from the study are similar to persons remaining in the study NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success interval (55) divided by the total number of persons alive at the start of the interval less one half of those withdrawing from the study (117). Subtracting this value from 100% results in a survival rate of 53% for the interval. For all people in the study, what is the probability of surviving to the end of the second year? The cumulative probability of survival through the second year equals the probability of survival for the first year multiplied by the probability for the second year. This equals 59% multiplied by 53%, or 31.3%. What is the probability chance of surviving 3 years after diagnosis? The cumulative survival probability for all 3 years equals the product of the independent interval survival probabilities. In this example, 59% multiplied by 53% multiplied by 70.4% gives a cumulative survival probability of 22%. 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? This calculation involves attributing the correct amounts of person-years to each group during an interval. For the first year of the study, 96 deaths occur. Using the median survival time, we can calculate that these persons contributed 48 person-years of observation. Additionally, 28 persons withdraw from the study. Again, allocating one half of the year to each of these patients results in 14 person-years. Of the remaining 124 persons who survive for the full year, they contribute 124 person- years of observation. The total person-time for the first year of the study is 186 person-years. Continuing with this same approach for years 2 & 3 of the study, we arrive at a total of 321.5 person- years of observed study time. 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: Chapters 7-8 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 reduction of disease i NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success R&omized clinical trial with stratified r&omization The characteristics of patients who failed to comply with the treatment dosages should be assessed as they NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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, & those with a first AMI who were at low risk for other cardiovascular diseases. Which term best describes the study design? A multicenter double-blind r&omized 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 r&omized 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 & 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? ARm&uolmticieznatteior ndowuabsle-sbulcincders&sfouml isziendcestutdhyewinavs ecsatrirgieadtoorust tdoidconmoptaarelttehretehffeecsteolef cdtriuognXowf ith that participants in either group in order to ensure equal percentages of men 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 r&omized 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 & 98 in the group receiving drug X. A preliminary analysis was conducted after 6 months & found that 87% of participants in the placebo group & 85% of those in the drug X group had taken more than 90% of their prescribed dosages. Which statement best describes this finding? may A multicenter double-blind r&omized 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 7days after infarction in 1,884 patients, 52% of all persons who were evaluated for entry into the NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Double blinding ensures that potential biases regarding selection, follow-up, & analysis can be reduced Correct because the rate of death is decreased in the drug X group NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success study. 945 participants were r&omized 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 & 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? A multicenter double-blind r&omized 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 r&omized 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 & 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: The following data come from a study of approaches to smoking cessation. Smokers who want to quit were r&omized 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 & support group QS who received quitting brochures as well as social support brochures listing benefits of smoking cessation, & telephone support group T who received the brochures & a monthly phone call from a counselor. Participants received mailed surveys at 8, 16, & 24 months after r&omization. The results after 2 years are in the table below. What is the overall quit rate after 2 years of follow-up? The overall quit rate after 2 years is 17.6%. This is estimated by summing the total number of those who quit smoking (331) & dividing by all participants who returned the survey after 2 years (1877). NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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 & 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, & 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? The rate of cancer incidence in the x-ray exposed group is 15 per 1,000 (49 divided by 3,263 multiplied by 1,000) & 7 per 1,000 in the nonexposed group (47 divided by 6,737 multiplied by 1,000). 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 & 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, & 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? The attributable risk equals the incidence rate in the exposed group minus the incidence rate in the nonexposed group. In this instance, the attributable risk is 8 per 1,000. This estimate is interpreted to mean that 8 of the 15 incident cases of cancer occurring in 1,000 children exposed to x-rays are due to the exposure itself. 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 & 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, & 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? The risk ratio is found by dividing the rate of cancers for each exposure group. In this instance, 15 per 1,000 (0.015) divided by 7 per 1,000 (0.007) equals a risk ratio of 2.1. This indicates that the risk of cancer is twice as high in children who received x-rays during their stay in the hospital. NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success The possibility that a factor which leads to exposure may be causally associated with the disease 0.04 5.00 NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success 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 & 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, & 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 & 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) Which of the following may be a factor that would result from the inability to use r&omization in a cohort study? 6,750 people who were free of disease X were enrolled in a cohort study in 1985 & followed with annual exams & interviews through 1995. Exposure to factor A was determined at study enrollment & 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? 6,750 people who were free of disease X were enrolled in a cohort study in 1985 & followed with annual exams & interviews through 1995. Exposure to factor A was determined at study enrollment & 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 relative risk for the effect of exposure to factor A on disease X? NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success Retrospective cohort study 3.1 NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success In 2002, investigators started a study of the association of cholesterol levels & stroke in a group of 2,000 healthy persons who had participated in a cholesterol screening program in 1992. The investigators determined exposure categories using cholesterol levels in all persons that were measured at the time of the screening program. A cutoff value of 200 mg/dL was used to define “high” cholesterol while those with levels below 200 were identified as having “low” cholesterol. Using this definition, 1,000 persons had “high” cholesterol levels while the remaining 1,000 persons had “low” cholesterol. The investigators determined that 150 cases of stroke occurred by the end of 2004, with 113 cases occurring in the high cholesterol group. What is the study design that the investigators used? In 2002, investigators started a study of the association of cholesterol levels & stroke in a group of 2,000 healthy persons who had participated in a cholesterol screening program in 1992. The investigators determined exposure categories using cholesterol levels in all persons that were measured at the time of the screening program. A cutoff value of 200 mg/dL was used to define “high” cholesterol while those with levels below 200 were identified as having “low” cholesterol. Using this definition, 1,000 persons had “high” cholesterol levels while the remaining 1,000 persons had “low” cholesterol. The investigators determined that 150 cases of stroke occurred by the end of 2004, with 113 cases occurring in the high cholesterol group. What type of risk measure should the investigators calculate? InRe20la0t2i,vienvreissktigators started a study of the association of cholesterol levels & stroke in a group of 2,000 healthy persons who had participated in a cholesterol screening program in 1992. The investigators determined exposure categories using cholesterol levels in all persons that were measured at the time of the screening program. A cutoff value of 200 mg/dL was used to define “high” cholesterol while those with levels below 200 were identified as having “low” cholesterol. Using this definition, 1,000 persons had “high” cholesterol levels while the remaining 1,000 persons had “low” cholesterol. The investigators determined that 150 cases of stroke occurred by the end of 2004, with 113 cases occurring in the high cholesterol group. Using the reported study data, what is the estimate of the risk measure that was chosen? NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success NURS 503 Week 8 Final Exam Study Guide 2022/2023 UPDATED GUARANTEED success A subject selected as a control may later be selected as R 503 Week 8 Final Exam Study Guide; Chapter 2-4, 5-6, 7-8, 9-15, 16-20 0.7 0.5 1.2 The separate stratum-specific odds ratios Effect modification by gender A case-control study of the relationship between high-fat diet & diabetes was performed. The results of the study are shown below, stratified by gender. What is the crude odds ratio for the association between high-fat diet & diabetes in this study? A case-control study of the relationship between high-fat diet & diabetes was performed. The results of the study are shown below, stratified by gender. What is the odds ratio among men only? A case-control study of the relationship between high-fat diet & diabetes was performed. The results of the study are shown below, stratified by gender. What is the odds ratio among women only? A case-control study of the relationship between high-fat diet & diabetes was performed. The results of the study are shown below, stratified by gender. Based on the responses above, what is the most appropriate measure of association to present when reporting the results of this study? A case-control study of the relationship between high-fat diet & diabetes was performed. The results of the study are shown below, stratified by gender. Which of the following is demonstrated by the stratified odds ratio shown above? When incidence density sampling is used in a case-control study, which of the following is an important consideration? To adjust for potential confounding by R 503 Week 8 Final Exam Study Guide; Chapter 2-4, 5-6, 7-8, 9-15, 16-20 Temporality Selection bias A recent prospective study on baldness & coronary heart disease (CHD) concluded that there was no association between the two, despite earlier cross-sectional studies which showed that baldness was associated with CHD when the two were determined at the same time in men. Which Bradford-Hill criterion is being tested by the newer study? A study examined the relation between use of estrogen replacement therapy (ERT) & ovarian cancer mortality using a prospective design. Of 24,231 eligible women, none had a prior history of cancer, hysterectomy, or ovarian surgery at enrollment in 1982. During 12 years of follow-up, 44 deaths from ovarian cancer occurred. In the published results, the authors note that 12,543 were excluded from the original cohort due to missing information for prior history variables. Which of the following is of greatest concern when interpreting the study results? A study examined the relation between use of estrogen replacement therapy (ERT) & ovarian cancer mortality using a prospective design. Of 24,231 eligible women, none had a prior history of cancer, hysterectomy, or ovarian surgery at enrollment in 1982. During 12 years of follow-up, 44 deaths from ovarian cancer occurred. In the published results, the authors note that 12,543 were excluded from the original cohort due to missing information for prior history variables. Age at menopause is a potential factor associated with use of ERT. The study investigators created three categories for age at menopause: less than 45 years, 46 through 54 years, & 55 years or more. After stratifying on age at menopause, the researchers reported relative risks of 0.97, 1.00 (referent), & 0.93 for each age group, respectively. Which of the following is true? Age at menopause is unlikely to be a strong confounder of the relationship between ERT use & ovarian cancer m A case-control study was conducted to assess whether occupational radiation exposure among men was associated with Down syndrome in their children. The investigators matched cases & controls on age of the mother at childbirth by 5-year categories. Why was this done? It is possible to study more than one exposure Classify subjects according to smoking status & compare occupational chemical exposures by each stratum 3,450 WChoinchfooufntdhienfgolbloyweinxgerisciasnealdevvaenltafoger othf othsee cwasiteh-codnatirloyl estxupdoysdueresigtno?automobile traffic A large case-control study using multiple recruitment centers was conducted comparing 2,987 lung smoker cases to 3,013 other hospitalized persons selected as controls. One objective was to study the association between occupational exposure to chemicals & lung cancer. After compiling the data, the investigators noted that 90% of persons with lung cancer were smokers while 67% of the controls were smokers. The most practical & efficient way to eliminate differences between the cases & controls with regard to smoking would be to: of sm An investigator is interested in studying the adverse effects of exposure to toxic metals on neurologic diseases such as Alzheimer’s disease. In assessing this risk, all of the following are important considerations for a prospective study design except: The difficulty in finding sufficient numbers of persons with neurologic disease in whom past metal exposures cou A history of dietary supplement with calcium was recorded among 10,000 women over the age of 50. The women were followed for 2 years to determine if they experienced hip fracture. Calcium supplementation was reported by 31% of women who experienced hip fracture & by 46% of all other women. In a case-control study with equal numbers of cases & controls, what is the number of women with a hip fracture who are not taking calcium supplements? A history of dietary supplement with calcium was recorded among 10,000 women over the age of 50. The women were followed for 2 years to determine if they experienced hip fracture. Calcium supplementation was reported by 31% of women who experienced hip fracture & by 46% of all other 0.67 Odds ratio = 0.53 There is a potential for selection bias which could be differential with respect to cases & controls women. What are the odds of a hip fracture among women who are taking calcium supplements? A history of dietary supplement with calcium was recorded among 10,000 women over the age of 50. The women were followed for 2 years to determine if they experienced hip fracture. Calcium supplementation was reported by 31% of women who experienced hip fracture & by 46% of all other women. What is the measure of association between calcium supplementation & hip fracture? In a study of 100 cases of colon cancer in women, there were 200 age- & race-matched controls. The suspected etiologic factor was higher-than-average consumption of red meat. The absolute risk of colon cancer in persons with this level of consumption is: WChaynnaroetcboentcroallscnuelaetdeedd in a case-control study? WThheeny ids oodndostrahtiaoveobtthaeineodutincoamcaeseo-fcoinnttreorlessttud&y aalrleolwiabfloeraepsptriomxiamtiaotinonofofetxhpeorseulartieve risk for frequency among those without the disease he general population? The exposure distribution among cases is representative of all persons with disease The exposure opportunity for controls is equivalent to the distribution of exposure opportunities for the population without the disease When the disease under investigation is rare in the population (All of the above) In a published epidemiologic study investigating infertility related to sexually transmitted diseases (STD), the authors state that 5% of identified cases refused enrollment, 10% of identified cases were lost to follow-up prior to data collection, & 10% of interviewed cases had missing data for one or more key variables describing exposure. Based on this information, which of the following statements is most likely to be true? In a published epidemiologic study investigating infertility related to sexually transmitted diseases t Increase internal validity The odds ratio for chlamydia is more precise than the odds ratio for gonorrhea Misclassification bias (STD), the authors state that 5% of identified cases refused enrollment, 10% of identified cases were lost to follow-up prior to data collection, & 10% of interviewed cases had missing data for one or more key variables describing exposure. After data were gathered for the study, the investigators decided to restrict the analysis to women only, rather than including both men & women in the study. Assuming that sex is a confounder of the exposure–disease relationship under investigation, this decision would have which of the following effects? In a published epidemiologic study investigating infertility related to sexually transmitted diseases (STD), the authors state that 5% of identified cases refused enrollment, 10% of identified cases were lost to follow-up prior to data collection, & 10% of interviewed cases had missing data for one or more key variables describing exposure. In the primary analysis of the study, the investigators measured exposure as a dichotomous variable (any history of STD compared to no history of STD). In subsequent analyses, the investigators looked at the relationship between specific STDs & infertility. They noted the following measures of association: for past history of gonorrhea, the odds ratio was 2.4 with a 95% confidence interval of 1.3 to 4.4. For past history of chlamydia, the odds ratio was 1.8 with a 95% confidence interval from 1.2 to 2.1. These results indicate that: If an investigator is analyzing the results of a clinical trial, then applying the “intention to treat” rule means that which type of bias is most likely to result? Investigators wanted to know if some military personnel are more error prone than others & would be a poor risk for training as a pilot. A study was done in which individuals who had injuries during basic training were compared to individuals who had not had an injury during training. Both groups were asked to recall episodes during childhood when they had had accidents that resulted in an injury. The individuals with a training injury reported more incidents during childhood when they had Information bias concerning past sunscreen use Decrease the odds ratio when prevalent cases are included 1.5 Increase above the true value A matched case-control study of sunscreen use during childhood & melanoma results in an odds ratio of 1.0. Cases of melanoma were matched by sex & race to controls who were identified by r&om digit dialing. What is the most likely explanation for the study’s null finding? Among patients with liver cancer, current alcohol drinkers have a worse prognosis for survival than nondrinkers. What would be the impact on the odds ratio for a case-control study of current alcohol use & liver cancer mortality if prevalent cases were included with incident cases of the cancer? In a cohort study, the reported relative risk was 2.0; however, the investigators concluded that the study likely had a bias away from the null hypothesis, but they concluded that an association did exist between the exposure & the outcome. The true relative risk is most likely: In a case-control study of maternal cigarette smoking as a risk factor for low birth weight, the investigators concluded that mothers of children with low birth weight were more likely to report smoking during pregnancy relative to mothers of children with normal birth weight. The reporting error most likely caused the odds ratio to: In a case-control study of obesity & adult-onset asthma, controls are matched to cases on the basis of race & gender. This approach to selection is intended to decrease the influence of which type of bias? InCoancafoseu-ncodnintrgol study of computer display exposure & glaucoma, cases & controls were also asked about television watching habits. Errors in recall of exposure to video screens occurred with equal frequency among cases & controls. Which one of the following biases likely occurred? Nondifferential misclassification Underestimated the true relationship Restriction of study subjects to those less than 50 years old Underestimated the true relationship It is a valid denominator for estimates of risk for individuals In a case-control study of computer display exposure & glaucoma, cases & controls were also asked about television watching habits. Errors in recall of exposure to video screens occurred with equal frequency among cases & controls. What is the most likely effect of this bias on the measure of association reported by the study? In a case-control study of computer display exposure & glaucoma, cases & controls were also asked about television watching habits. Errors in recall of exposure to video screens occurred with equal frequency among cases & controls. Which of the following methods for adjusting for confounding by age is most likely to affect the generalizability of the study findings? In a cohort study of occupational exposure to a chemical & subsequent incidence of bladder cancer, all workers who smoked were more likely to die of other causes before bladder cancer was diagnosed. What was the effect of this premature mortality on the measure of association reported by the study? Which of the following statements about person-years is not true? Chapters 16-20 A large company institutes a new wellness program aimed at improving the health of its 50,000 employees. As a part of the program, all employees are given physical examinations & screening tests. One of the tests given to male employees is the prostate specific antigen (PSA) test with all employees testing positive being referred to their private physician for a thorough examination involving the st&ard test, a digital rectal examination (DRE). What will happen to the apparent incidence rate of prostate cancer in the company during the first year of this program? study is the A/A genotype. The neurologic condition is thought to be autosomal dominant with respect to the gene; therefore, one copy of the m allele should induce the development of the condition. What is the odds ratio for subjects with at least one copy of the mutant allele? Employment status is correlated with health 75.4 89% No, the odds of disease among heterozygotes is 0.46 The data in the table below are from a case-control study of a genetic factor associated with neurologic disease. Cases are newly diagnosed persons with the rare neurologic condition, & population controls were used for comparison. Investigators have hypothesized that a single point mutation in a gene on the 10th chromosome is strongly related to the disease. In the table, subjects who are homozygous for the mutation are denoted as m/m; subjects with only one mutated gene (heterozygous for the mutation) are denoted as A/m; & subjects with two normal alleles (homozygous for the absence of the mutation) are denoted as A/A. The unexposed category for the study is the A/A genotype. The neurologic condition is thought to be autosomal dominant with respect to the gene; therefore, one copy of the m allele should induce the development of the condition. Using the odds ratio calculated above, what is the population attributable risk percent for the mutation? The data in the table below are from a case-control study of a genetic factor associated with neurologic disease. Cases are newly diagnosed persons with the rare neurologic condition, & population controls were used for comparison. Investigators have hypothesized that a single point mutation in a gene on the 10th chromosome is strongly related to the disease. In the table, subjects who are homozygous for the mutation are denoted as m/m; subjects with only one mutated gene (heterozygous for the mutation) are denoted as A/m; & subjects with two normal alleles (homozygous for the absence of the mutation) are denoted as A/A. The unexposed category for the study is the A/A genotype. The neurologic condition is thought to be autosomal dominant with respect to the gene; therefore, one copy of the m allele should induce the development of the condition. Does this study confirm the hypothesis that the condition is caused by an autosomal dominant mutation? Why or why not? The basis for the healthy worker effect is that: Epidemiologists were interested in investigating the relationship between exercise & development of coronary heart disease (CHD) among women. Women ages 45 to 55 years were interviewed to determine their exercise habits at entry into the study. They were then followed for 15 years to determine the incidence of CHD in the cohort. What proportion of women who developed CHD had exercised once per week? The best answer is 60%. 67 cases of CHD occurred during the 15-year follow-up period. 40 of the cases (60%) developed in women who exercised once per week Epidemiologists were interested in investigating the relationship between exercise & development of coronary heart disease (CHD) among women. Women ages 45 to 55 years were interviewed to determine their exercise habits at entry into the study. They were then followed for 15 years to determine the incidence of CHD in the cohort. Complete the table by calculating the incidence rates per 10,000 person-years & the rate ratios. Rates per 10,000 person-years: 7.00, 3.41, 1.59 by increasing exercise frequency. Rate Ratios: Referent, 0.49, 0.23 by increasing exercise frequency. To calculate the rates per 10,000 person-years, divide the number of incident CHD cases by the total person-years exposed & multiply by 10,000 to st&ardize the rates. For example, among women who reported no exercise, 23 cases divided by 32,843 person-years gives a rate of 0.0007 events per person- year. After multiplying by 10,000, the rate equals 7.00 events per 10,000 person-years. To estimate the rate ratio, one group must be designated the referent group. All estimated ratios are relative to this group’s rate. In this study, the nonexposed group was comprised of women who reported no exercise at baseline. The rate ratio comparing the group exercising once per week to this referent category equals 3.41 divided by 7.00, or 0.49. Epidemiologists were interested in investigating the relationship between exercise & development of coronary heart disease (CHD) among women. Women ages 45 to 55 years were interviewed to determine their exercise habits at entry into the study. They were then followed for 15 years to determine the incidence of CHD in the cohort. The investigators concluded that these data demonstrate a causal relationship between exercise & subsequent CHD. Which of the Hill criteria best applies to this data? Which of the following are characteristics of a disease that are important for the conduct of an effective screening program? More than one answer may be correct. High prevalence of the disease The disease has a severe effect on health Treatment reduces the duration of the disease Selection of a screening population at high risk for the disease Lead-time bias due to early detection of incurable disease Reduction in proportion of deaths due to infectious diseases in the first part of the 20th century Exposure is constant over time Cause-specific mortality rate The type of population served by the new unit has changed Which factor can increase the positive predictive value (PPV) estimated for a screening program? When evaluating disease screening programs, what is a potential bias of the measure of their effectiveness when compared to symptom-based diagnostic approaches? What is the epidemiologic transition? For a cross-sectional study to be a valid test of a hypothesis, which of the following must be true? Which of the following measures is best suited to the evaluation of a screening program over time? After a hospital in a major city adds a high-risk pregnancy & neonatal intensive care unit (NICU), the rate of adverse childbirth outcomes doubles. Administrators are concerned that this indicates that the new unit is ineffectively run. Which of the following is a reason that this concern may be unfounded? Migrants tend to maintain similar lifestyles to their country of origin 43% The association is not real due to confounding by other risk factors for lung cancer Exposure to the etiologic factor must precede the onset of the disease In a study of immigrants to a new country, the rate of cardiovascular disease (CVD) in migrants is equivalent to the rate of CVD in their home country. This rate is lower than the rate for first generation family members & for their country of adoption. Which of the following could explain this observation? A large cohort study of 1,000 adult pairs of twins was conducted. Seventy-two pairs of twins were concordant for the disease under investigation, & 94 pairs of twins were discordant for the disease. In the remaining twin pairs, neither adult had the disease. What is the concordance rate for this disease among all twin pairs with at least one affected member? A large cohort study of 1,000 adult pairs of twins was conducted. 72 pairs of twins were concordant for the disease under investigation while 94 pairs of twins were discordant for the disease. In the remaining twin pairs, neither adult had the disease. From this observation, what is the most likely interpretation? WCiathninnoat labregedmetaenrumfaicnteudrinfgrocmomtphaensye, tdhaetdaivision responsible for the production of agricultural chemicals has an annual rate of lung cancer equal to 17.3 cases per 100,000 persons. The rate of lung cancer for the rest of the company not exposed to agricultural chemical production is 13.6 cases per 100,000 persons. What inference can be made concerning the association of agricultural chemical production & lung cancer within this company? For an etiologic factor to be judged to be causally related to a disease, which of the following must be true?