Deck 5: Epidemiology, Biostatistics, and Medical Informatics

Question 1

A novel portable cholesterol-measuring gadget is being developed for use in underprivileged medical settings. A patient's cholesterol level is discovered to be 200 mg/dL, 201 mg/dL, and 200 mg/dL on three independent readings of the same blood sample during clinical trials of an early prototype. The identical sample had a cholesterol level of 260 mg/dL when measured using the gold standard technique. Which of the following best describes the new cholesterol-measuring device? )High accuracy; high precision
B)High accuracy; low precision
C)High sensitivity; low specificity
D)Low accuracy; high precision
E)Low accuracy; low precision
F)Low sensitivity; high specificity

Answer 1

D
Eductional Objective: Precision (reliability) is a test's ability to replicate equal or comparable results with repeated measurements (bottom half of figure).
The capacity of a test to measure what it is designed to assess is referred to as accuracy (validity). To be accurate, a novel test's results must be equal to those obtained with a gold standard (e.g., the best conventional test available) on the same individual (right half of figure).
Repeated tests of the same blood sample produced virtually similar results in this example, indicating that the new gadget had excellent accuracy. However, none of the new device's measurements were equal to the gold standard's results (i.e., the measurements are inaccurate), indicating that the new device has low accuracy.

Question 2

A novel biomarker has been demonstrated to aid in the early diagnosis of non-small cell lung cancer. A preliminary review of a cohort trial of this novel test shows that its use increases lung cancer patient survival by 3 months when compared to individuals identified using conventional techniques. A subsequent investigation indicates no difference between the two groups in 6-month death rates. Which of the following variables best explains the study's findings?

A)Confounding
B)Lead-time bias
C)Length-time bias
D)Measurement bias
E)Observer bias
F)Rare disease assumption

Answer 2

Lead-time bias

Question 3

Researchers are looking at the link between colorectal cancer and the usage of nonsteroidal anti-inflammatory drugs. They interviewed a group of patients with biopsy-proven colorectal cancer, followed by a group of patients' neighbors of comparable age and race. The study is based on comparing the outcomes of two individuals with similar features (one from each of the two groups). Which of the following possible issues with this study is best addressed by this design technique?

A)Ascertainment bias
B)Confounding
C)Observer bias
D)Recall bias
E)Selection bias

Answer 3

Confounding

Question 4

A geneticist is curious about the possible causes of a congenital anomaly. She speculates that acetaminophen usage during the first trimester of pregnancy may be linked to the anomaly. In her study, a random sample of moms with and without the anomaly is drawn from official birth data. Personal interviews with the moms are then done to identify fetal exposure to acetaminophen. According to the findings, moms of children who did not have the anomaly used acetaminophen less often throughout the first trimester. Which of the following forms of bias is most likely to occur in this sort of study?

A)Allocation bias
B)Detection bias
C)Recall bias
D)Referral bias
E)Selection bias

Question 5

A hospital wants to know how common diabetic nephropathy is in the general population of persons with type 2 diabetes. Kidney biopsy samples are collected from 500 adult diabetic patients receiving medical treatment. The samples are then analyzed by ten different pathologists, five of whom work at the hospital and five at surrounding institutes. According to early findings, pathologists who work for the hospital are three times more likely than those who do not work for the hospital to interpret biopsy samples as diabetic nephropathy. Which of the following is the most plausible explanation for this discrepancy in interpretation?

A)Confounding
B)Lead-time bias
C)Observer bias
D)Recall bias
E)Selection bias

Question 6

A research is being conducted to evaluate the effectiveness of spironolactone in patients with heart failure. For two years, 450 patients are given either spironolactone or a placebo. Neither the patients nor the doctors are aware of who is taking the medicine or the placebo. The above-mentioned study design is most successful in preventing:

A)Beta error
B)Recall bias
C)Observer bias
D)Effect modification
E)Selection bias

Question 7

A physician behavior researcher is curious about how frequently primary care providers check patients' sexual histories during clinic visits. Patients who visit a primary care clinic are invited to complete a questionnaire immediately following their consultation with their doctor as part of the research. Which of the following is most likely to be a possible concern if the physicians become aware that their own conduct is being observed?

A)Berkson's bias
B)Hawthorne effect
C)Lead-time bias
D)Pygmalion effect
E)Recall bias

Question 8

A group of researchers conducted a case-control study to determine the link between pesticide exposure and head and neck squamous cell carcinomas. Cases and controls were age and gender matched. The individuals' exposure status was assessed through interviews. The odds ratio in matched-pair analysis is 7.5. (95 percent confidence interval: 2.3-14.8). Based on this information, which of the following is most likely to have an impact on the study's validity?

A)Confounding bias by age
B)Healthy worker bias
C)Misclassification bias
D)Nonresponse bias
E)Placebo effect

Question 9

An epidemiologist wishes to undertake a research on the spread of hepatitis C (HCV) in a nation with poor healthcare resources. She has access to a cohort of newly diagnosed HCV adults as well as an age-matched cohort of HCV-negative people. She intends to undertake a case-control study with these two adult cohorts. Which of the following measures of interest would be most suited for this researcher's study?

A)The average death rate in each cohort
B)The frequency of past blood transfusions in each cohort
C)The incidence rate of liver cancer in HCV-positive participants
D)The rate of eventual HCV infection in HCV-negative participants
E)The rate of treatment-related adverse effects in HCV-positive participants

Question 10

Left atrial pressure may be estimated using pulmonary capillary wedge pressure (PCWP) measurements; the typical range is 6-12 mm Hg, and recorded values are whole numbers. Over the course of two hours, a patient in the critical care unit has 20 serial PCWP measures collected. The maximum recorded value among these 20 observations is 12 mm Hg, while the minimum recorded value is 10 mm Hg. Which of the following is most likely to remain unaltered if the next measurement is 26 mm Hg?

A)Mean
B)Mode
C)Range
D)Standard deviation
E)Variance

Question 11

A sample of children age 2-5 years is chosen at random from an outpatient clinic.  The number of urinary tract infections (UTIs) over a 1-year period is given in the figure below. What was the average number of UTI episodes over 1 year for a child in this sample?

A)Between 0 and 1
B)1
C)Between 1 and 2
D)2
E)Between 2 and 3

Question 12

A 65-year-old man with a history of congestive heart failure is admitted to the cardiac care unit after experiencing chest discomfort and hypotension. An intra-arterial line is inserted to monitor blood pressure directly. His intra-arterial blood pressure measurements are 75, 110, 80, 90, 75, and 110 mm Hg. Which of the following blood pressure values indicates the mean?

A)80 mm Hg
B)85 mm Hg
C)90 mm Hg
D)100 mm Hg
E)110 mm Hg

Question 13

A team of scientists conducts a study to assess the pharmacologic qualities of oxfendazole, an antihelminthic drug. Healthy volunteers are given escalating oral dosages of oxfendazole (0.5 to 60 mg/kg) as part of the study. Data is gathered to create a pharmacokinetic profile of the medication and its metabolites, and the occurrence of side effects is documented for each dose level. The study includes 20 healthy male and female (nonchildbearing potential) subjects. Oxfendazole has been proven to be well tolerated over the whole dosage range, with no significant side effects or fatalities. Which of the following statements best defines this sort of research?

A)Preclinical study
B)Phase I clinical trial
C)Phase II clinical trial
D)Phase III clinical trial
E)Phase IV clinical trial

Question 14

A research is being carried out to evaluate the potential therapeutic benefit and treatment-related toxicity of tandutinib in combination with bevacizumab in patients with recurrent glioblastoma. The research included 41 individuals with recurrent, bevacizumab-naive glioblastoma. Starting on day 15, the treatment consisted of tandutinib 500 mg twice day and bevacizumab 10 mg/kg every 2 weeks. According to the study findings, all patients had treatment-related toxicities; the most prevalent grade 3 toxicities were hypertension (17.1%), muscular weakness (17.1%), lymphopenia (14.6%), and hypophosphatemia (9.8 percent ). The data was then compared to prior clinical trial findings evaluating the therapeutic benefit of bevacizumab monotherapy. They concluded that tandutinib in combination with bevacizumab was as efficacious but more harmful than bevacizumab alone. Which of the following statements best defines this sort of research?

A)Preclinical study
B)Phase I clinical trial
C)Phase II clinical trial
D)Phase III clinical trial
E)Phase IV clinical trial

Question 15

A surveillance research is being done to evaluate the efficacy and safety of tolvaptan, a medication that is presently being used in clinical settings to treat heart failure with volume overload. The trial included 8,300 participants with various medical comorbidities who were given tolvaptan once daily in the morning for two weeks. Tolvaptan displayed aquaretic effectiveness in patients with diuretic-resistant volume overload, however hypernatremia occurred in a limited percentage of individuals. To prevent hypernatremia, researchers suggested a lower dose of tolvaptan in people with normonatremia and hypokalemia. Which of the following statements best defines this sort of research?

A)Preclinical study
B)Phase I clinical trial
C)Phase II clinical trial
D)Phase III clinical trial
E)Phase IV clinical trial

Question 16

A prospective research with a relative risk (RR) of 1.81 and a p-value of 0.03 reveals a relationship between alcohol use and transitional bladder cancer. They next divide the research participants into two groups, smokers and nonsmokers, and evaluate the relationship between alcohol use and bladder cancer once more: Which of the following best explains the difference between the overall and stratified results?

A)Confounding
B)Effect modification
C)Measurement bias
D)Meta-analysis
E)Observer bias
F)Recall bias

Question 17

A big prospective research is looking into the link between alcohol intake and breast cancer. Through a random selection of residence locations, 4000 middle-aged women are included in the research. Periodic surveys are used to examine daily alcohol intake and breast cancer incidence. The authors report a relative risk of 1.32 (95 percent confidence range = 0.90-1.85) for alcohol intake and breast cancer after a five-year follow-up; 800 participants were lost to follow-up at the conclusion of the research, the majority of whom were moderate to heavy alcohol drinkers. Which of the following biases is most likely to be present and may have influenced the results, based on this information?

A)Lead-time bias
B)Observer bias
C)Random misclassification bias
D)Recall bias
E)Selection bias

Question 18

For the treatment of postmenopausal symptoms, a novel estrogen receptor agonist is being studied. A prospective research found that the medicine raises the incidence of DVT in treated women who smoke compared to untreated women who smoke, with a relative risk (RR) of 1.70 and a p-value of 0.01. In nonsmokers, there is no increased incidence of DVT with drug use (RR = 0.96; p-value = 0.68). Which of the following best characterizes this occurrence?

A)Confounding
B)Effect modification
C)Latent period
D)Observer bias
E)Selection bias

Question 19

Inflammatory biological indicators are clinically valuable in a variety of ways, including determining disease activity in disorders such as systemic lupus erythematosus (SLE). In individuals with active SLE flares, a novel inflammatory marker is being studied. When the new marker's blood level (in mg/L) is plotted against the C-reactive protein (CRP) level (also in mg/L), the following plot results: Based on the plot, the correlation coefficient between the 2 variables is closest to which of the following values?

A)+0.8
B)+0.2
C)0
D)-0.2
E)-0.8

Question 20

A research team is looking into the relationship between BMI and blood pressure in a random sample of youngsters aged 12 to 16. Following data collection, they do a correlation analysis at a 1% significance level. The researchers discover that BMI has a r = 0.46 (p 0.001) correlation with systolic blood pressure and a r = 0.37 (p 0.001) correlation with diastolic blood pressure. Which of the following interpretations of these results is most accurate?

A)An increase in BMI causes a statistically significant increase in blood pressure in children
B)Childhood obesity significantly increases the risk of cardiovascular disease later in life
C)There is a statistically significant negative linear relationship between BMI and blood pressure in children
D)There is a statistically significant positive linear relationship between BMI and blood pressure in children
E)There is no statistically significant linear relationship between BMI and blood pressure in children

Question 21

A placebo-controlled clinical study was done by a research team to see whether a novel medicine for treating acute migraine with or without aura in adults is more effective than usual treatment. In the trial, 3,500 individuals with acute migraine were randomly allocated to either the novel medicine or usual therapy. The researchers opt to set alpha to 0.01 rather than 0.05 during the data analysis phase. Which of the following outcomes is most likely as a result of this change?

A)Any significant findings will be reported with greater confidence
B)There will be a higher probability of a type I error
C)There will be a higher probability of finding statistically significant results
D)There will be a lower probability of a type II error
E)The study will have more statistical power

Question 22

A group of scientists seeks to find out what causes hospital-acquired bacteremia caused by methicillin-resistant Staphylococcus aureus (MRS A). Following MRSA was identified from a blood sample collected from them on the third or subsequent day after admission, 45 patients were recruited in the research. In addition, 90 individuals admitted to the hospital during the same time period with a duration of stay of more than two days who did not have bacteremia were chosen at random. The frequency of variables such as central line or urine catheter placement and surgical site infection was then compared between the two groups. Which of the following null hypotheses is most relevant for this study?

A)Hazard ratio is equal to 1
B)Hazard ratio is not equal to 1
C)Odds ratio is equal to 1
D)Odds ratio is not equal to 1
E)Relative risk is equal to 1
F)Relative risk is not equal to 1

Question 23

A study looked at the link between a new vaccination and traveler's diarrhea (TD). Researchers chose a random sample of persons who planned to travel to areas where they were at higher risk for TD and who had gotten the new vaccination, as well as a separate random sample of people who planned to travel to the same areas but had not received the new vaccine. These two groups of tourists were evaluated for the presence of TD during the trip and for seven days after returning home. Which of the following association measurements are the investigators most likely to report?

A)Incidence
B)Median survival time
C)Odds ratio
D)Prevalence
E)Relative risk

Question 24

A randomized controlled study was done to evaluate the efficacy of a novel medication in reducing severe cutaneous responses in individuals with rheumatoid arthritis treated with adalimumab. 75 persons with rheumatoid arthritis were given the new medicine in addition to adalimumab, whereas the other 75 got a placebo in addition to adalimumab. According to the findings, six individuals in the new treatment group experienced severe cutaneous responses, compared to nine in the placebo group. Which of the following best describes the new medication group's relative risk decrease for severe cutaneous reactions?

A)0)08
B)0)10
C)0)12
D)0)33
E)0)67

Question 25

A meta-analysis of multiple trials on the effect of cocoa consumption on systolic blood pressure (SBP) yielded the following findings: All of the trials looked at the change in SBP after two weeks. Which of the following is the most appropriate conclusion based on the data?

A)A higher mean SBP was seen in the cocoa groups overall
B)Cocoa intake should be recommended for blood pressure management
C)Cocoa intake was associated with a statistically significant decrease in SBP
D)Studies 2, 6, and 7 showed a statistically significant increase in SBP
E)There was no statistically significant change in SBP overall

Question 26

A health care accrediting group is conducting an annual evaluation of a suburban hospital. Iatrogenic infection rates for all key hospital services are examined as part of the procedure. The data for inpatient surgical infections during the last year are provided below. In this hospital, what is the case-fatality rate for methicillin-resistant S aureus surgical infections?

A)40/70
B)40/110
C)40/75
D)53/100
E)70/220

Question 27

According to a comprehensive investigation of blood folate levels in a sample of women aged 16 to 45, this parameter is normally distributed, with a mean of 5.0 ng/mL and a standard deviation of 0.5 ng/mL. According to the findings of the study, 95 percent of serum folate measurements in these individuals will fall roughly between which of the following limits?

A)3)5 and 6.0 ng/mL
B)3)5 and 6.5 ng/mL
C)4)0 and 6.0 ng/mL
D)4)0 and 5.5 ng/mL
E)4)5 and 5.5 ng/mL

Question 28

An intern in the endocrinology department is tasked with doing a chart review of all patients hospitalized with diabetes-related cardiovascular problems in the previous 6 months. According to the intern's early data analysis, there were 400 such patients, and their blood cholesterol levels were regularly distributed, with a mean of 220 mg/dL and a standard deviation of 10 mg/dL. Based on these findings, how many individuals in this research could be predicted to have blood cholesterol levels more than 240 mg/dL?

A)2
B)10
C)20
D)64
E)128

Question 29

A medical student is reviewing the charts of patients who have been hospitalized to the local emergency department with severe pancreatitis. He wants to compare blood glucose levels in moderate and severe instances. He chooses to do a descriptive study of the factors in each group before attempting to compare the mean blood glucose levels between the two groups of patients. The distribution of blood glucose levels in patients with severe acute pancreatitis was found to be strongly positively skewed. Which of the following statements about the data for the severe acute pancreatitis group is most likely correct?

A)The mean is equal to the median
B)The mean is equal to the mode
C)The mean is greater than the median
D)The median is greater than the mean
E)The mode is greater than the mean

Question 30

Blood pressure readings are taken from a group of people who have no known medical issues. For men and women, the mean readings and related standard deviations (SDs) for systolic blood pressure (SBP) are shown by age group: If hypertension is defined as SBP >140 mm Hg, approximately what percentage of men age 35-44 in this sample will be classified as having hypertension, assuming a normal (Gaussian) distribution?

A)16%
B)34%
C)50%
D)68%
E)84%
F)95%

Question 31

A study was carried out to determine the age at menarche in young female gymnasts. Gymnasts were split into two groups based on their devotion to the sport: competitive gymnasts and leisure gymnasts. Assuming that age at menarche is normally distributed, which of the following is closest to the probability that a randomly chosen competitive gymnast will have onset of menarche at age 16 and more?

A)0)997
B)0)950
C)0)680
D)0)160
E)0)025
F)0)0015

Question 32

A team of psychiatrists undertakes a double-blind, placebo-controlled randomized study to assess the effectiveness and safety of cariprazine for the treatment of depressive episodes associated with bipolar I disorder (bipolar depression) in adults. The treatment response rate for cariprazine was 46% against 32% for placebo, while the rate for all adverse events was 7% for cariprazine versus 5% for placebo. The rate differences were statistically significant. Which of the following is the estimated number of patients who must be exposed to cariprazine in order to injure 1 person who would not have been harmed otherwise?

A)2
B)8
C)14
D)21
E)50

Question 33

A medical study group is examining the efficacy of Superstatin, a novel lipid-lowering medicine that is being promoted directly to consumers as a revolutionary new therapy to prevent heart attacks. The drug's producer claims that it is more efficacious than currently available hypolipidemic medicines in the primary prevention of myocardial infarction. The following are the findings of a 5-year, randomized, double-blind, controlled trial to assess the effectiveness of Superstatin. Compared to the control medication, how many patients need to be treated with Superstatin to prevent one additional myocardial infarction?

A)2
B)5
C)23
D)48
E)67
F)92
G)100

Question 34

Zeracizumab is an investigational angiogenesis inhibitor that targets vascular endothelial growth factor and is being evaluated for the treatment of advanced non-squamous non-small cell lung cancer that has not responded to chemotherapy (NSCLC). To establish the clinical effectiveness of the experimental treatment, the pharma firm analyzes 1-year survival following treatment as part of the review procedure. The outcomes are shown in the table below.   Which of the following best describes the zeracizumab-containing regimen's number needed to harm?

A)2
B)25
C)40
D)72
E)94

Question 35

A research is being carried out to evaluate the efficacy of a novel medicine X added to conventional antihypertensive therapy vs standard antihypertensive therapy alone in avoiding the development of proteinuria in patients recently diagnosed with essential hypertension. Five years following diagnosis, 97 of 100 patients on drug X with conventional antihypertensive therapy did not develop proteinuria, but 90 of 100 patients on standard antihypertensive therapy did. Which of the following indicates the approximate number of patients with essential hypertension who need to be treated with medicine X to prevent 1 additional patient from getting proteinuria within 5 years, based on these findings?

A)3
B)7
C)10
D)15
E)70

Question 36

Treatments A and B are two new investigational drugs being evaluated for the treatment of an unique respiratory virus infection in children that causes abrupt respiratory collapse and mortality. The 2-week survival following treatment is analyzed as part of the testing procedure to establish the clinical effectiveness of the investigational medications. A total of 60 children who have just been diagnosed with the condition are randomly randomized to take Drug A, Drug B, or placebo in a 1:1:1 ratio.   which of the following statements comparing the effectiveness of Drugs A and B in treating children infected with the novel virus is most appropriate?

A)Drugs A and B require treating the same number of children to prevent 1 additional death, so they are equally effective
B)Drug A requires treating fewer children to prevent 1 additional death compared to Drug B, so Drug A is less effective than Drug B
C)Drug A requires treating fewer children to prevent 1 additional death compared to Drug B, so Drug A is more effective than Drug B
D)Drug A requires treating more children to prevent 1 additional death compared to Drug B, so Drug A is less effective than Drug B
E)Drug A requires treating more children to prevent 1 additional death compared to Drug B, so Drug A is more effective than Drug B

Question 37

A research is being done to evaluate the efficacy of beta-blocker medication in patients suffering from acute myocardial infarction (MI). The study discovered that 20 individuals out of 90 who used a beta-blocker in the week preceding a MI experienced a severe arrhythmia incident while hospitalized. The study also discovered that 30 of the 70 individuals who did not use a beta-blocker suffered a severe arrhythmia. What was the chances ratio of getting significant arrhythmia in individuals who used beta-blockers against those who did not?

A)(20 × 30) / (70 × 40)
B)(20 × 40) / (70 × 30)
C)(20 × 70) / (30 × 40)
D)(20 / 50) / (70 / 110)
E)(20 / 90) / (30 / 70)

Question 38

A researcher wants to see if there is a link between neural tube abnormalities and the usage of acetaminophen during the first three months of pregnancy. He selects a group of women at random who have recently had kids with neural tube abnormalities and a second group of women who have just delivered babies who appear to be healthy. Following that, these two groups were asked about their usage of acetaminophen throughout the first three months of pregnancy. Which of the following association measurements are the investigators most likely to report?

A)Median survival
B)Odds ratio
C)Prevalence ratio
D)Relative rate
E)Relative risk

Question 39

The purpose of this case-control research is to look at the relationship between probiotic yogurt consumption before and throughout pregnancy and gestational diabetes mellitus (GDM) in women over the age of 18 during their 24 to 28 week singleton pregnancy. The investigators collect a history of probiotic yogurt use in both patients and controls. The study's findings are displayed below. Which of the following best represents the odds of high probiotic yogurt intake in women with GDM compared to women without GDM?

A)0)17
B)0)45
C)0)66
D)1)51
E)2)20

Question 40

A total of 1,040 women with SLE and 1,260 women without SLE are recruited for a case-control research to look at a possible link between endometriosis and SLE. In both groups of women, the investigators question about a history of endometriosis. 240 women with SLE had a history of endometriosis, while 210 women without SLE had a history of endometriosis. What is the estimated chances ratio of endometriosis in women with SLE vs women without SLE?

A)0)1
B)0)7
C)0)8
D)1)2
E)1)5

Question 41

According to one study, the average blood cholesterol level in 200 non-diabetic hospitalized patients is 195 mg/dL and 210 mg/dL in 180 diabetic hospitalized patients. The stated likelihood that the observed difference is attributable to chance alone is 5%. There is also a 20% chance of determining that there is no change in blood cholesterol levels when there is. What is the study's strength?

A)0)05
B)0)20
C)0)50
D)0)80
E)0)95

Question 42

A 62-year-old man with diabetes, hypertension, and hyperlipidemia arrives at an academic medical center's emergency room complaining of chest discomfort, nausea, vomiting, and diaphoresis. An ECG reveals ST elevation in the anterior leads, as well as substantially increased cardiac enzymes. The center's researchers are planning a randomized controlled study to explore the hypothesis that medication B will reduce the mortality associated with acute ST-elevation myocardial infarction relative to standard of care. Which of the following would investigators want to optimize to guarantee that they do not miss a difference between medication B and standard of treatment (if one exists)?

A)a
B)B
C)Type I error
D)Type II error
E)1 - B

Question 43

Researchers examining the impact of hormone replacement therapy (HRT) on the risk of myocardial infarction (MI) in postmenopausal women estimated the relative risk (RR) of MI to be 1.30 (p = 0.07) in women who use HRT vs those who do not. According to the researchers, there is no statistically significant increased risk of MI with HRT (based on a threshold of = 0.05). Following that, the findings of a meta-analysis show that postmenopausal women who use HRT had an elevated risk of MI, with an overall RR = 1.32 (p = 0.03) compared to those who do not. In the first study, which of the following was the most likely problem?

A)Berkson's bias
B)Placebo effect
C)Poor blinding
D)Researcher expectancy
E)Sample size

Question 44

A doctor is undertaking a double-blind randomized controlled experiment to see if a new cream might lower the likelihood of recurrence in chronic recurrent atopic dermatitis. A total of 30 patients with moderate to severe atopic dermatitis who were undergoing a flare were randomly divided into two groups: 15 received the new cream, and 15 received just emollient. After two weeks of therapy, the new cream group had a 25% recurrence rate, whereas the emollient alone group had a 50% relapse rate. The difference, however, is not statistically significant (p = 0.14). According to the doctor, using the new cream does not lessen the likelihood of recurrence in chronic recurrent atopic dermatitis. Which of the following is most likely to explain the results of the study?

A)Ascertainment bias
B)Confounding bias
C)Ecologic fallacy
D)Insufficient statistical power
E)Recall bias

Question 45

In 2016, the population of a state was expected to be 4,000,000 people. The state recorded 20,000 cases of a rare and deadly neurological illness at the start of the same year. The state recorded 7,000 new cases and 1,000 fatalities linked to this illness by the end of 2016. At the conclusion of the year, another 40,000 fatalities from all causes were documented. What was the disease's cumulative incidence in 2016?

A)1,000 / 4,000,000
B)6,000 / 3,980,000
C)6,000 / 4,000,000
D)7,000 / 3,980,000
E)7,000 / 4,000,000
F)26,000 / 3,959,000
G)41,000 / 4,000,000

Question 46

A research is being done to evaluate the prevalence of catheter-associated urinary tract infection (CAUTI) in an urban hospital's critical care unit (ICU). The graph below depicts the number of CAUTI cases among ICU patients in this hospital for the month of July. Which of the following is the number of common cases on July 31 based on the plot?

A)1
B)4
C)5
D)8
E)9

Question 47

A 28-year-old lady arrives at the office to begin care. She just relocated to New York to work as a copy editor for a large newspaper. There are no known medical issues with her. The patient and her husband are in a monogamous relationship. She frequently eats fast food at lunch and cooks in the evenings with her spouse. She visits the gym around every two weeks. The patient's temperature is 36.7 C (98 F), his blood pressure is 118/64 mm Hg, his pulse is 60 beats per minute, and his respirations are 14 / minute. Her body mass index (BMI) is 24.6 kg/m². The physical exam is ordinary. The laboratory findings are within the expected range. Which of the following is an example of counseling this patient on food and exercise habits?

A)Case finding
B)Cognitive-behavioral therapy
C)Community-level intervention
D)Health promotion
E)Health risk assessment
F)Precontemplative stage intervention
G)Tertiary prevention

Question 48

The population pyramid of a certain country is shown below. Based on the diagram, which of the following best characterizes this population?

A)High mortality rate
B)Long life expectancy
C)Low birth rate
D)Shrinking population
E)Stable population

Question 49

A research is carried out to describe a country's age-sex distribution. According to official data, the country's population pyramid looks like this. Which of the following statements about this country and its people is most likely correct, according to the population pyramid?

A)The country seems to have high birth rates; therefore, the population must be growing
B)The country seems to have a high death rate; therefore, the population must be shrinking
C)The country seems to have a low birth rate; therefore, the population must be old
D)The country seems to have a short life expectancy; therefore, the population must be young
E)The country seems to have a similar percentage of people in each age cohort; therefore, the population must be stable

Question 50

The population pyramid of all races and ethnicities for a certain state in the United States is shown below. Which of the following statements best describes the population of this specific state?

A)Life expectancy is low due to its high mortality rate
B)The high birth rate indicates the population is growing
C)The population is shrinking due to the migration of older people
D)The similar number of people in each age cohort indicates the population is stable
E)The state has a young population because of its high birth rate

Question 51

A research lab creates a novel serologic test to identify prostate cancer. To evaluate sensitivity and specificity characteristics, the novel test is compared to transrectal ultrasound-guided prostate biopsy. The test results are reported to be negative in 95 percent of persons who do not have the condition. What is the likelihood of all eight test results being negative if the new assay is performed on eight blood samples collected from people without prostate cancer?

A)0)05 × 8
B)0)95 × 8
C)0)05⁸
D)0)95⁸
E)1 - 0.05⁸
F)1 - 0.95⁸

Question 52

A group of psychiatrists has detected an unusually high number of elderly people suffering from depression in the local neighborhood. It is decided to perform a cross-sectional research to evaluate the prevalence of depression in this particular group. The following are estimates of the community's depression prevalence (cases per 100 people): 11ec160b 3715 f593 9249 bb76ef083814 MD0001 00 Suppose a psychiatrist meets a 65-year-old lady, a 72-year-old man, and an 84-year-old woman from this neighborhood during an afternoon clinic. What is the likelihood that none of the three patients suffers depression if there is no relationship between them?

A)0)001
B)0)011
C)0)295
D)0)705
E)0)999

Question 53

A prospective cohort research was carried out to investigate the impact of daily alcohol use in the development of breast cancer. The researchers discovered a 5-year relative risk of 1.4 for persons who drink alcohol on a regular basis against those who do not. The 95% confidence interval ranged from 1.02-1.85. Which of the following p-values best fits the data mentioned above?

A)0)03
B)0)06
C)0)09
D)0)11
E)0)20

Question 54

A rheumatoid arthritis (R A) genome-wide association study (GWAS) is being conducted on a cohort of Portuguese patients, including 907 cases with RA and 1,524 controls without RA. To examine the relationship between RA and hundreds of thousands of loci, logistic regression is performed. These findings are then compared to data from a European GWAS cohort of 4,036 RA patients and 6,959 non-RA patients. Finally, the findings of the Portuguese and European studies are merged in a meta-analysis. Based on these findings, the researchers discover three additional loci related with RA using a significance level criterion of 5 - 10⁸:   Previous research has found 30 loci that accounted for 35% of RA disease heredity. Which of the following statements is correct regarding this study?

A)Combining the results of the European and Portuguese studies into a meta-analysis decreases the power
B)Logistic regression is used because there is a stepwise increase in the strength of association from Locus 1 to Locus 3
C)The association between Locus 1 and RA in the meta-analysis is not statistically significant because the odds ratio is <1
D)The threshold used for the p-value in the meta-analysis is 5 × 10^-8 because of the large number of loci studied
E)With this meta-analysis, the 33 identified loci account for most disease heritability in RA

Question 55

In a reference sample of hundreds of healthy subjects, the laboratory reference range for a novel marker of cardiac injury is 0.04-0.08 U/mL at the standard 95% level of probability.  The marker has very high sensitivity and specificity for myocardial tissue.  The clinical cardiology team would like to use a 99.7% reference range to assess patients who come to the emergency department with chest pain and have a high pretest probability of cardiac ischemia.  An elevated value of the marker is defined as exceeding the 99.7th percentile of the reference sample.  Assuming a normal (Gaussian) distribution with a mean of 0.06 U/mL, which of the following most closely approximates the corresponding reference range?

A)0)03 to 0.09
B)0)035 to 0.085
C)0)045 to 0.075
D)0)05 to 0.07
E)0)055 to 0.065

Question 56

A research compared the effect of a low-carbohydrate diet on body weight to that of a low-fat diet. A sample of 150 overweight but otherwise healthy people from a big metropolis were enrolled in the trial and randomly allocated in a 1:1 ratio to either the low-carbohydrate (40 g/d) or the low-fat (7 percent saturated fat) diet. At 12 months, the low-carbohydrate diet group lost more weight than the low-fat diet group, with a mean difference in body weight loss of 3.5 kg (p = 0.01, predefined significance threshold = 0.05). Which of the following is the most correct interpretation of the study's findings?

A)The observed mean difference in body weight change of -3.5 kg is not statistically significant
B)The probability of observing a mean difference in body weight change of -3.5 kg is 0.01
C)There is a 1% chance of observing a mean difference in body weight change of at least -3.5 kg when no difference between groups is assumed
D)There is a 1% chance that an adult on a low-carbohydrate diet will have a body weight change of at least -3.5 kg at 12 months after starting the diet
E)There is a 1% chance that the mean difference in body weight change is biased in favor of the low-carbohydrate diet group

Question 57

The findings of a recent research on the relationship between glycosylated hemoglobin (HbA1c) levels and high-sensitivity C-reactive protein (hs-CRP) levels in individuals with type II diabetes mellitus (T2DM) are as follows: "Our findings suggest that HbA1c levels are favorably linked with hs-CRP levels (r = 0.80). The likelihood that these results were due to chance alone is 3%, with a 10% possibility of concluding that there is no association between HbA1c and hs-CRP when omitted "e does exist." Based on this data, which of the following is the most likely p-value and power of the correlation test in the study?

A)A
B)B
C)C
D)D
E)E
F)F

Question 58

UWRLD99, a new serum biomarker, is being studied for the early identification of pancreatic cancer. UWRLD99 concentrations (measured in international units [IU] per dL) have been reported to be increased in pancreatic cancer patients. The image below depicts test results from 200 volunteers ("healthy") and 190 patients with biopsy-proven pancreatic cancer ("diseased"). The researchers used a threshold of 200 IU/dL to establish the sensitivity and specificity of UWRLD99 for pancreatic cancer (indicated by the solid vertical line).  Which of the following would most likely be observed if they had selected a lower cutoff, as indicated by the dashed vertical line?

A)Higher number of false negatives
B)Higher positive predictive value
C)Higher sensitivity
D)Lower number of false positives
E)Lower number of true positives

Question 59

A new research is being done to compare the effectiveness of intravenous immunoglobulin vs analgesics in the treatment of pain in individuals with idiopathic small fiber neuropathy. A total of 100 eligible patients who met the inclusion/exclusion criteria are randomly allocated to one of two groups by a computer. Which of the following is the most likely outcome of this study's approach of allocating patients to treatment groups?

A)One group in which participants are blinded to the intervention they receive and another in which participants are not
B)One group in which researchers but not participants are aware of the intervention received and another in which participants but not researchers are aware of the intervention received
C)Two groups of participants that will only be analyzed based on their initial treatment allocation
D)Two groups that have equal numbers of participants
E)Two groups in which participants are similar in underlying characteristics

Question 60

A randomized, double-blind, placebo-controlled clinical study of a novel medication for the treatment of peripheral neuropathy in adults with multiple myeloma is being conducted by an investigator (MM). The trial includes 150 individuals with MM who are randomly assigned to receive either the new medicine (n = 75) or a placebo (n = 75). According to the trial design, participants in both groups must take one medication every day and keep a pain diary. After three months of therapy, each patient is interviewed and their pain diaries are examined; nine patients on the new medicine and three patients on the placebo did not take the tablets as directed. The investigator decides to analyze the trial data using the intention-to-treat principle.  Which of the following best describes how the data pertaining to all patients who did not adhere to protocol should be treated?

A)Conduct separate analyses of the 12 nonadherent patients and the 138 adherent patients
B)Exclude all 12 nonadherent patients from analysis
C)Exclude the 3 nonadherent patients in the group taking placebo from analysis
D)Exclude the 9 nonadherent patients in the group taking the new drug from analysis
E)Keep all 12 nonadherent patients in their respective groups for analysis

Question 61

A clinical trial is looking at the use of five distinct biomarkers for detecting Barrett esophagus (BE), the only known precursor lesion of esophageal cancer. Researchers assess each biomarker's performance and offer estimates of sensitivity, specificity, and area under the curve (AUC).   Which biomarker is the most reliable?

A)1
B)2
C)3
D)4
E)5

Question 62

In one research, medication A was compared to conventional treatment in the prevention of recurrent pulmonary embolism (PE). The absolute risk decrease for medication A compared to usual care was 4%. In the usual treatment group, the incidence of recurrent PE was 6%. There were 24 individuals in the drug A group who got recurrent PE. How many people were in the drug A group in total?

A)600
B)900
C)1200
D)1500
E)1800
F)2100

Question 63

A research is being conducted to assess the effectiveness of KM28, a novel medication. The trial will compare KM28 with standard treatment to standard care alone in terms of lowering the risk of recurrent breast cancer. The FDA will approve the new medicine if KM28 with standard treatment reduces the incidence of breast cancer recurrence by at least 40% when compared to conventional therapy alone. On usual treatment, the recurrence rate is reported to be 8%. What is the maximum incidence of recurrent illness acceptable for women treated with KM28 with conventional treatment in order for the FDA to approve KM28?

A)2)8%
B)3)2%
C)3)6%
D)4)8%
E)5)2%

Question 64

A 45-year-old man arrives at the office for a normal check-up. The patient has a first-degree relative who has Alzheimer's disease and is worried about contracting the condition. He read in the papers that a lack of yellow and orange fruits and vegetables has been linked to Alzheimer's disease and wants to know how likely he is to get the condition. A recent cohort research that examined the relationship between blood carotene content and Alzheimer disease was discovered in a medical literature review. A 20-year follow-up study of 200 middle-aged participants having a first-degree relative with Alzheimer dementia was conducted to assess the illness's progression. The outcomes are as follows: Assuming the patient's carotene levels are low, what is his 20-year risk of developing Alzheimer disease?

A)0)19
B)0)23
C)0)27
D)0)30
E)0)40

Question 65

A major cohort research is being done to examine the relationship between smoking and esophageal squamous cell cancer in middle-aged Chinese males. During a 10-year follow-up, smokers had a 5 times higher incidence of esophageal cancer than nonsmokers (relative risk = 5.0, 95 percent confidence range = 2.9-7.1). What proportion of squamous cell carcinoma of the esophagus among smokers may be related to smoking, according to the research findings?

A)25%
B)50%
C)70%
D)80%
E)90%

Question 66

Angiotensin-converting enzyme (ACE) drugs were studied in the prevention of cardiac events in diabetic individuals. During a 5-year follow-up period, 120 of 400 diabetic individuals who had taken an ACE inhibitor suffered an acute coronary event. During the same time period, 100 of 300 diabetic individuals who did not use an ACE inhibitor suffered a cardiac incident. What was the risk of suffering a cardiac incident in diabetes individuals on ACE inhibitors versus diabetic patients not taking ACE inhibitors?

A)(120x100)/(280x200)
B)(120x200)/(100x280)
C)(120x280)/(100x200)
D)(120/220)/(280/480)
E)(120/400)/(100/300)

Question 67

A prospective research looks at the link between frequent antioxidant supplement usage (vitamins C and E) and the risk of stroke in males aged 40-60 who are physically active. The study compares the risk of stroke among men who used antioxidant supplements for 5 years to the risk of stroke among men who did not take antioxidant supplements for 5 years, as compared to a control group of men who never took antioxidant supplements. When compared to the reference group, men who consumed antioxidant supplements for 5 years and men who consumed antioxidant supplements for 5 years had stroke relative risks of 0.95 (p = 0.45) and 0.75 (p = 0.01), respectively. The study's findings were modified to account for baseline variations in healthy habits and  overall health.   Which of the following factors most likely explains why the relative risk of stroke is lower with longer antioxidant use?

A)Accumulation effect
B)Lead-time bias
C)Observer bias
D)Rare disease assumption
E)Selection bias

Question 68

A 65-year-old man arrives to the office because his family is concerned about his persistent cough after smoking. The patient inquires about the possibility of adult smokers having chronic obstructive pulmonary disease (COPD). According to a recent cohort research, the relative risk (RR) of COPD for nonsmokers is 0.10 and for moderate smokers is 0.40 when compared to heavy smokers. The patient is a light smoker. According to the study, which of the following is the relative risk of COPD among moderate smokers vs nonsmokers?

A)0)10
B)0)25
C)0)40
D)2)5
E)4
F)10

Question 69

A 73-year-old man visits the office for a check-up. He was diagnosed with CLL three years ago after normal laboratory tests indicated a significantly high leukocyte count. He is in good spirits. On examination, he was found to have stable lymphadenopathy. He has been researching treatment alternatives if his CLL progresses and is interested in an investigational medication that preferentially binds malignant cells. The medicine has been proven to considerably improve survival in people with stage 3 and 4 CLL while not curing the disease. If this new drug were widely used, what changes would be expected in the number of incident and prevalent cases of CLL?

A)The number of incident cases will decrease, the number of prevalent cases will decrease
B)The number of incident cases will increase, the number of prevalent cases will not change
C)The number of incident cases will decrease, the number of prevalent cases will increase
D)The number of incident cases will not change, the number of prevalent cases will increase
E)The number of incident cases will not change, the number of prevalent cases will not change

Question 70

An epidemiological research is being conducted to investigate the impact of type II diabetes on a large population with limited migration. Over a 30-year period, disease incidence and prevalence are tracked and documented as the number of cases per 1,000 people. Which of the following is the most plausible cause for the graph's shift in illness prevalence?

A)Decreased hospitalization rate
B)High mortality in diabetics
C)Improved quality of care
D)Increased accuracy of diagnostic testing
E)Increased exposure to risk factors
F)Increased number of new diabetes cases
G)Selective survival bias

Question 71

The graph below depicts the yearly incidence of viral hepatitis per 100,000 people in the United States from 1982 to 2012. (US). The overall population of the United States increased throughout this time period, as seen in the table below: 11ec160b 371f 9291 9249 659e3ae21c65 MD0001 00 The number of people at risk of hepatitis infection is considered to be equal to the whole US population at any given moment. Which of the following is more likely based on this information?

A)After 2006, hepatitis B prevalence surpassed hepatitis A and hepatitis C prevalence
B)In 1987, there were as many individuals with hepatitis A as with hepatitis B in the US
C)In 1989, there were more individuals with hepatitis A than with hepatitis B in the US
D)In 1997, there were more new cases of hepatitis A than of hepatitis B and C combined
E)The number of new cases of hepatitis A diagnosed in 1982 and 1998 were exactly the same

Question 72

In patients with severe aortic stenosis, a randomized controlled trial is being conducted to compare transcatheter aortic valve replacement (TAVR) with surgical aortic valve replacement using a self-expanding transcatheter aortic valve bioprosthesis. The goal is to calculate the difference in risk of mortality from any cause. Seven hundred forty-seven patients with severe aortic stenosis who are at high surgical risk are recruited and randomly randomized to TAVR or surgical valve replacement groups. Following discharge, there are follow-up examinations at one month, six months, and one year. The following are the 1-year follow-up results:  Which of the following better depicts the absolute risk decrease for mortality from any cause in TAVR patients compared to surgical replacement patients? 

A)(68/357) - (57/390) = 0.044
B)[(68/357) - (57/390)] / (68/357) = 0.233
C)(57/390) / (68/357) = 0.767
D)(68/357) / (57/390) = 1.303
E)1 / [(68/357) - (57/390)] = 22.562

Question 73

For the previous 15 years, the prevalence of a chronic condition that primarily affects older people has been stable in a community. Many young healthy people leave the population as a result of worsening economic situations that have no influence on the sickness itself. Which of the following is the most likely effect of emigration on illness prevalence estimates in the coming years?

A)The prevalence would decrease
B)The prevalence would increase
C)The prevalence would remain the same
D)It is not possible to determine the effect on prevalence from the information given

Question 74

A new trial on a novel test for identifying acute myocardial infarction (AMI) has been begun. The test's sensitivity is assessed to be 75% and its specificity to be 80%. The research includes 600 patients, 200 of whom are AMI instances as established by the diagnostic gold standard. How many false negatives may be anticipated in the study?

A)50
B)80
C)120
D)150
E)400

Question 75

A novel dipstick test for identifying urinary tract infections is being tested in a research facility (UTIs). To establish diagnostic test parameters, the novel test is compared to urinalysis of a midstream urine specimen (considered the diagnostic gold standard). The trial includes 300 individuals, 100 of whom had a UTI as diagnosed by urinalysis. The novel dipstick test has been shown to be 70% sensitive and 90% specific for the identification of UTIs. The study has how many false positives?  

A)20
B)30
C)70
D)120
E)180

Question 76

A novel tumor marker is being researched for its potential application in the diagnosis of ovarian cancer. A 400-woman sample is divided into two groups depending on the presence or absence of BRCA mutations. Serum levels of the novel marker are measured in both groups, and both groups of women are subjected to standard screening to identify their illness status. The top curves depict the distribution of the new serum marker in women with BRCA mutations, whereas the bottom curves depict the distribution of the new serum marker in women without BRCA mutations. The recommended serum marker cutoff value for both groups is   . Use of the new serum marker in women with BRCA mutations, compared with those without BRCA mutations, is associated with which of the following?

A)Higher sensitivity and higher specificity
B)Higher sensitivity and lower specificity
C)Higher sensitivity and same specificity
D)Lower sensitivity and higher specificity
E)Lower sensitivity and lower specificity
F)Lower sensitivity and unchanged specificity
G)Unchanged sensitivity and unchanged specificity

Question 77

A novel biomarker for the early identification of invasive stomach cancer has been found. When compared to endoscopy with several biopsies, it offers a sensitivity of 89 percent and a specificity of 85 percent. The test is employed in two populations: one in the United States, where 5 out of 100,000 people have stomach cancer, and another in China, where 100 out of 100,000 people have the disease. Which of the following statements about this new test is the most accurate?

A)Negative predictive value of the test is lower in the American population
B)Positive predictive value of the test is higher in the Chinese population
C)Sensitivity of the test is higher in the American population
D)Specificity of the test is higher in the Chinese population
E)The test is not reliable in the American population

Question 78

The table below summarizes the findings of a research looking at a novel diagnostic test for acute myocardial infarction (MI).   What is the new diagnostic test's sensitivity?

A)25%
B)37.5%
C)50%
D)75%
E)79%
F)80%

Question 79

A novel test for detecting urinary tract infections in women is being tested. Positive urine dipstick plus urine culture is the gold standard for comparison. The study's findings are presented below.  What is the specificity of the new test?

A)10%
B)30%
C)50%
D)70%
E)90%

Question 80

A 45-year-old woman arrives to the office complaining of a palpable thyroid node. According to her medical history, she was diagnosed with medulloblastoma as a youngster and treated with chemotherapy and external beam radiation. Thyroid fine-needle aspiration reveals no cancerous cells. "What are the possibilities that I don't have thyroid cancer?" the patient wonders as the test findings are revealed to her. Which of the diagnostic test parameters listed below would be most helpful in addressing this patient's question?

A)Negative predictive value
B)Positive predictive value
C)Sensitivity
D)Specificity
E)Validity