STEP 3 – Biostatistics & Epidemiology 2

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Title

Effect of vitamin D₃ supplements on development of advanced cancer

Objective

To investigate whether vitamin D₃ supplementation has an effect on advanced (metastatic or fatal) cancer among adults without a diagnosis of cancer at baseline.

Methods

Design: Randomized, placebo-controlled trial. Median intervention period of 5.3 years (range: 3.8-6.1 years).

Participants: 25,871 participants (51% female; mean [SD] age 67.1 [7.1]).

Exposure: Vitamin D₃ (cholecalciferol 2,000 IU/d) or placebo; BMI (categorized as <25 kg/m², 25-29 kg/m², and ≥30 kg/m²).

Outcome: Incidence of any metastatic cancers and cancer mortality.

Results

In general, vitamin D₃ was associated with a significant reduction in metastatic or fatal cancers compared with placebo (hazard ratio [HR]: 0.83, 95% confidence interval [CI]: 0.69-0.99). However, the associations were inconsistent across BMI levels.

Outcomes	Number of events in groups		HR^† (95% CI)
Outcomes	Vitamin D₃ (N = 12,927)	Placebo (N = 12,944)	HR^† (95% CI)
Total metastatic cancer
BMI <25 kg/m²	24	39	0.63 (0.38-1.05)
BMI 25-29 kg/m²	37	46	0.80 (0.52-1.23)
BMI ≥30 kg/m²	25	24	1.15 (0.42-1.89)
Cancer mortality
BMI <25 kg/m²	38	68	0.58 (0.39-0.86)
BMI 25-29 kg/m²	66	74	0.89 (0.64-1.23)
BMI ≥30 kg/m²	46	39	0.99 (0.75-1.76)
CI = confidence interval; HR = hazard ratio. †Analyses are from Cox regression models controlling for age and sex.

Conclusion

This research suggests the need to incorporate body composition to better interpret and understand the effects of vitamin D₃ on the incidence of advanced (metastatic or fatal) cancer.

A graduate student conducting research on the association between vitamin D₃ supplementation and cancer is reviewing the abstract of a recently published journal article.

Item 1 of 2

Which of the following conclusions can be drawn from the results of the study?

A. BMI modifies the effect of vitamin D3 on metastatic cancer
B. Only BMI ≥30 kg/m2 is significantly associated with an increase in metastatic cancers
C. The effect of vitamin D3 on cancer mortality is significant only for certain individuals
D. Vitamin D3 is significantly associated with a reduction in cancer mortality regardless of BMI level

Correct

Incorrect

Question 15 of 40

15. Question

Title

Effect of vitamin D₃ supplements on development of advanced cancer

Objective

To investigate whether vitamin D₃ supplementation has an effect on advanced (metastatic or fatal) cancer among adults without a diagnosis of cancer at baseline.

Methods

Design: Randomized, placebo-controlled trial. Median intervention period of 5.3 years (range: 3.8-6.1 years).

Participants: 25,871 participants (51% female; mean [SD] age 67.1 [7.1]).

Exposure: Vitamin D₃ (cholecalciferol 2,000 IU/d) or placebo; BMI (categorized as <25 kg/m², 25-29 kg/m², and ≥30 kg/m²).

Outcome: Incidence of any metastatic cancers and cancer mortality.

Results

In general, vitamin D₃ was associated with a significant reduction in metastatic or fatal cancers compared with placebo (hazard ratio [HR]: 0.83, 95% confidence interval [CI]: 0.69-0.99). However, the associations were inconsistent across BMI levels.

Outcomes	Number of events in groups		HR^† (95% CI)
Outcomes	Vitamin D₃ (N = 12,927)	Placebo (N = 12,944)	HR^† (95% CI)
Total metastatic cancer
BMI <25 kg/m²	24	39	0.63 (0.38-1.05)
BMI 25-29 kg/m²	37	46	0.80 (0.52-1.23)
BMI ≥30 kg/m²	25	24	1.15 (0.42-1.89)
Cancer mortality
BMI <25 kg/m²	38	68	0.58 (0.39-0.86)
BMI 25-29 kg/m²	66	74	0.89 (0.64-1.23)
BMI ≥30 kg/m²	46	39	0.99 (0.75-1.76)
CI = confidence interval; HR = hazard ratio. †Analyses are from Cox regression models controlling for age and sex.

Conclusion

This research suggests the need to incorporate body composition to better interpret and understand the effects of vitamin D₃ on the incidence of advanced (metastatic or fatal) cancer.

Item 2 of 2

The graduate student is interested in conducting further studies among individuals with BMI <25 kg/m². Which of the following statements regarding these individuals is best supported by the abstract?

A. Having a BMI <25 kg/m2 decreases the risk of cancer mortality by 58%
B. Supplementation with vitamin D3 significantly reduces the risk of metastatic cancer in individuals with BMI <25 kg/m2
C. The risk of cancer mortality is significantly reduced in individuals with BMI <25 kg/m2 who supplement their diets with vitamin D3
D. Vitamin D3 supplementation is not significantly associated with metastatic cancer or cancer mortality in individuals with BMI <25 kg/m2

Correct

Incorrect

Question 16 of 40

16. Question
A large randomized double-blinded study compares a new inhalational steroid agent to fluticasone in patients with moderate persistent asthma. The following results are highlighted in the study:

The investigators conclude that the study drug is more effective in this patient population. Which of the following is the major limitation of this conclusion?
- A. Clinical significance
- B. Lack of power
- C. Lead-time bias
- D. Surrogate endpoint
- E. Type 1 error
Correct

Incorrect
Question 17 of 40

17. Question
A 64-year-old man with chronic and severe acid reflux comes to the office for follow-up. The patient is taking proton pump inhibitors (PPIs) and is worried about a recent medical publication reporting a significant increase in the risk of gastric cancer with long-term PPI usage. The study evaluated a cohort of 500 adult patients diagnosed with severe acid reflux. Of these, 200 had been taking PPIs for at least 5 years and 300 had never taken PPIs. One hundred individuals who had taken PPIs for at least 5 years developed gastric cancer and 75 individuals who had not taken PPIs developed gastric cancer. Based on the data in this study, which of the following is the relative risk of developing gastric cancer in individuals who take PPIs for at least 5 years as compared with individuals who do not take PPIs?
- A. Patients who take PPIs for at least 5 years have four times the risk of developing gastric cancer
- B. Patients who take PPIs for at least 5 years have three times the risk of developing gastric cancer
- C. Patients who take PPIs for at least 5 years have two times the risk of developing gastric cancer
- D. Patients who take PPIs for at least 5 years have the same risk of developing gastric cancer
- E. The risk for developing gastric cancer cannot be determined from the data
Correct

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Question 18 of 40

18. Question
A 22-year-old woman comes to the office for a drug test as part of her job application. The patient has never used recreational drugs or excessive amounts of alcohol. Examination is unremarkable. Compared with persons with known substance use disorder, which of the following statements best applies to this patient?
- A. The test should have a lower negative predictive value
- B. The test should have a lower positive predictive value
- C. The test should have a lower prevalence
- D. The test should have a lower sensitivity
- E. The test should have a lower specificity
Correct

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Question 19 of 40

19. Question
A study investigates the prevalence of ischemia in 512 patients with chest pain undergoing stress testing. Only patients with negative cardiac enzymes and nondiagnostic electrocardiogram changes are included. Myocardial perfusion imaging for ischemia and coronary artery calcification (CAC) score are obtained for each participant. The following results are reported:

Which of the following best describes the study design?
- A. Case-control study
- B. Case series
- C. Cross-sectional study
- D. Prospective cohort study
- E. Randomized clinical trial
Correct

Incorrect
Question 20 of 40

20. Question
A study evaluated the accuracy of using midstream urine (MSU) culture to identify the causative pathogen in patients with uncomplicated cystitis. Women ages 18-49 with symptoms of cystitis provided MSU specimens for culture. The investigators also collected urine by means of a urethral catheter for culture, which served as the gold standard for confirming the causative pathogen. Bacterial growth was determined in colony forming units per mL. Correlation coefficients (r) were calculated for several organisms by comparing the logarithm of bacterial growth in urethral catheter specimens to that of bacterial growth in MSU specimens. The following plots were reported:

Which of the following organisms identified by MSU most likely has the lowest positive predictive value in revealing the causative pathogen for cystitis?
- A. Enterococci
- B. Escherichia coli
- C. Group B streptococci
- D. Klebsiella pneumoniae
- E. Staphylococcus saprophyticus
Correct

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Question 21 of 40

21. Question
Abstract:

Hypothesis: Exposure to vinyl chloride increases the risk of liver and other cancers.

Methods:

Design: Cohort study

Participants: 10,250 men employed in the manufacture of vinyl chloride or polyvinyl chloride resin between 1942 and 1972.

Exposure: Job and department assignments were used to assign each cohort member to similar exposure groups, and a cumulative exposure index was constructed to account for exposure level and duration of exposure.

Outcome measures: Mortality rates by age, calendar interval for cause-specific categories of cause of death, and facility location were obtained, and standardized mortality ratios were calculated for overall and cause-specific categories of death through December 31, 2015.

Results:
Observed and expected deaths, and standardized mortality ratios for selected causes of death among vinyl chloride workers, were as follows:

The abstract applies to the next 2 items.

Item 1 of 2

Based on the data, which of the following statements is most accurate concerning exposure to vinyl chloride in the cohort of 10,250 workers?
- A. Brain cancer, melanoma, and non-Hodgkin lymphoma mortality were significantly elevated among workers.
- B. Exposure to vinyl chloride significantly reduces the risk for Hodgkin disease among workers.
- C. Mortality from laryngeal cancer and lung cancer among workers is not statistically lower than expected.
- D. The expected number of deaths from liver cancer among workers was significantly higher than the observed number.
- E. The observed number of deaths among workers was significantly higher for cancers of the connective and soft tissues.
Correct

Incorrect
Question 22 of 40

22. Question
Abstract:

Hypothesis: Exposure to vinyl chloride increases the risk of liver and other cancers.

Methods:

Design: Cohort study

Participants: 10,250 men employed in the manufacture of vinyl chloride or polyvinyl chloride resin between 1942 and 1972.

Exposure: Job and department assignments were used to assign each cohort member to similar exposure groups, and a cumulative exposure index was constructed to account for exposure level and duration of exposure.

Outcome measures: Mortality rates by age, calendar interval for cause-specific categories of cause of death, and facility location were obtained, and standardized mortality ratios were calculated for overall and cause-specific categories of death through December 31, 2015.

Results:
Observed and expected deaths, and standardized mortality ratios for selected causes of death among vinyl chloride workers, were as follows:

Item 2 of 2

The authors of the study decide to conduct an ancillary statistical analysis in which a second cohort of workers employed in the manufacture of domestic textiles is used as the population of reference. Based on the study results from the first cohort of vinyl chloride workers, which of the following is the most likely reason for the ancillary analysis?
- A. All-cause mortality among the vinyl chloride workers is statistically lower than among the general population.
- B. Compared to the general population, vinyl chloride workers had a nonstatistically significant association with mortality due to melanoma and lung cancer.
- C. Considering a cohort of domestic textile workers reduces the possibility of contamination bias.
- D. Misdiagnosis of early angiosarcoma of the liver might have influenced the association between vinyl chloride exposure and hepatocellular carcinoma.
- E. The expected number of deaths among domestic textile workers will be greater than in the general population.
Correct

Incorrect
Question 23 of 40

23. Question
A group of investigators is exploring trends in the incidence of coronary heart disease (CHD) in a large population. The investigators studied several factors in relation to the incidence of the disease. The relationships between cigarette sales in the population (in average number of cigarette packs sold per person per day) and the incidence of CHD (per 1000 people) over time are given on the figure below:

Which of the following is the best statement concerning the results of the study?
- A. Coronary heart disease (CHD) incidence shows no stable trend over time
- B. Individuals from this population who quit smoking have a decreased risk of CHD
- C. Sales of cigarettes in the population increased over time
- D. The plot cannot provide individual-level conclusions
- E. There are discordant changes in cigarette sales and CHD incidence
Correct

Incorrect
Question 24 of 40

24. Question
A 10-year-old boy is brought to the office by his parents for a follow-up visit. The patient has sickle cell disease (SCD) and says that he has had an increase in the number of pain crises in the past 12 months. The parents ask whether their child can receive the recently approved Drug Z for the treatment of vasoocclusive crises (VOCs) in patients with SCD. The drug trials’ snapshot summary for Drug Z states that its benefit was evaluated in 2 randomized, placebo-controlled trials in adults with SCD who had 4 to 8 VOCs in the 12 months before they were enrolled in the trials. The first trial (n = 61) showed that therapy with high-dose Drug Z resulted in a significantly lower rate of VOCs than placebo (45.3% lower rate; p < 0.01). The second trial (n = 32) showed that therapy with low-dose Drug Z resulted in a significantly lower rate of VOCs than placebo (35.8% lower rate; p = 0.01). Which of the following conclusions can be drawn about this situation?
- A. The 2 trials showed similar benefits in adults with SCD, so this patient is likely to significantly benefit from Drug Z
- B. The 2 trials were conducted in populations that were similar to each other, so it is difficult to determine whether these results apply to this patient
- C. The internal validity for both trials is threatened because neither adjusted for other covariates, so the real effect of Drug Z on SCD is unknown
- D. There is misclassification of exposure bias in both trials because they included different dosages, so it is not clear what the benefit of Drug Z for this patient might be
- E. Trial 2 was underpowered due to small sample size, so it is unlikely that this patient will have a significant improvement if given Drug Z
Correct

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Question 25 of 40

25. Question

A case-control study is conducted to determine whether pregnancy and the postpartum period are risk factors for cerebral venous thrombosis (CVT). Researchers adjusted for age and history of cancer and stratified for pregnancy versus postpartum period (0 to 6 versus 7 to 12 weeks postpartum). Odds ratios (ORs) with a 95% confidence interval were calculated to compare the odds of CVT during pregnancy or postpartum period relative to the absence of pregnancy and postpartum period. An excerpt of study results is shown in the table below:

Association between pregnancy or postpartum period & CVT
	Unadjusted OR (95% CI)	*Adjusted OR (95% CI)**
Pregnancy or postpartum	4.7 (3.1, 7.1)	3.8 (2.4, 6.0)
Pregnancy	1.6 (0.8, 2.9)	1.2 (0.6, 2.3)
Postpartum	14.0 (7.5, 26.0)	10.6 (5.6, 20.0)
0-6 weeks postpartum	23.8 (10.8, 52.2)	18.7 (8.3, 41.9)
7-12 weeks postpartum	3.0 (0.8, 11.1)	2.0 (0.5, 7.7)
Adjustment for age & history of cancer. CI = confidence interval; CVT* = cerebral venous thrombosis; OR = odds ratio.

When age and history of cancer are controlled, which of the following is the most appropriate conclusion regarding these data?

A. Age and history of cancer are strong risk factors for CVT
B. Pregnancy and postpartum periods are equally associated with CVT
C. The postpartum odds of CVT was lower during the first 6 weeks compared with 7-12 weeks
D. The risk of CVT is significantly higher in pregnant women than in nonpregnant women
E. The stratification showed that only recent delivery is strongly associated with CVT

Correct

Incorrect

Question 26 of 40

26. Question
A new, randomized, placebo-controlled trial studied the association between treatment with 250,000 IU cholecalciferol for 4 months following hip fracture surgery and incidence of falls. Results showed that at month 4 after surgery, 7 (6.3%) patients in the treatment group reported >1 falls compared to 23 (21.2%) in the placebo group (p < 0.01); there was a relative risk reduction of 70.3%. Treatment with 250,000 IU cholecalciferol for 4 months costs $100 per patient. Based on this information, how much would it cost to treat enough patients after hip surgery with 250,000 IU cholecalciferol to prevent >1 falls during the first 4 months of therapy?
- A. $142
- B. $300
- C. $671
- D. $1430
- E. $6300
Correct

Incorrect

Question 27 of 40

27. Question

Researchers are evaluating the performance measures of a novel newborn screening test for an autosomal recessive condition that may be performed 24 to 72 hours after birth. An excerpt of the results is presented below:

	Time of newborn screening (after birth)
Performance of new test	24 hours	72 hours
Sensitivity	0.58 (0.07-0.65)	0.61 (0.30-0.92)
Specificity	0.87 (0.82-0.92)	0.85 (0.79-0.91)
Positive predictive value	0.16 (0.09-0.23)	0.18 (0.05-0.31)
Negative predictive value	0.94 (0.89-0.96)	0.96 (0.92-1.00)
Values in parentheses represent 95% confidence intervals.

Which of the following is the most accurate statement regarding these data?

A. The specificity of the test is greater at 24 hours after birth than at 72 hours after birth
B. The test is an excellent screening test for the detection of the autosomal recessive condition
C. The test is less sensitive at 24 hours after birth than at 72 hours after birth
D. The test performs best when screening newborns without the autosomal recessive condition
E. The test performs worse at 24 hours after birth than at 72 hours after birth

Correct

Incorrect

Question 28 of 40

28. Question
A group of rheumatologists wants to investigate 8 candidate rheumatoid arthritis (RA) susceptibility loci to identify whether single nucleotide polymorphisms (SNPs) are associated with RA in a given population. Eight SNPs (MTHFR C677T, MTHFR A1298C, TGFβ1 T869C, TNFB A252G, VDR ApaI, VDR BsmI, VDR FokI, VDR TaqI) are tested by genotyping patients with RA (n = 105) and unrelated patients without RA (n = 80) as controls. Which of the following is the most appropriate null hypothesis for this study?
- A. Odds ratio is equal to 1
- B. Odds ratio is not equal to 1
- C. Relative risk is equal to 1
- D. Relative risk is not equal to 1
Correct

Incorrect
Question 29 of 40

29. Question
A randomized, parallel-group, controlled clinical trial evaluates the effectiveness of an anti-inflammatory intervention as treatment for neuropathic pain following spinal cord injury. Participants with varying levels and severities of spinal cord injury are randomly assigned to either a 24-week, anti-inflammatory diet treatment group or a control group. Primary outcomes consist of changes in pain scores and markers of inflammation at 6 months. Preliminary analyses reveal a significant reduction in pain scores in the treatment group from baseline to 6 months (p = 0.03). There was a significant reduction in pain scores among nonobese subjects (p = 0.01) and a nonsignificant increase in pain scores among obese subjects (p = 0.06). Which of the following is the best explanation for these differences in findings between obese and nonobese subjects?
- A. Confounding bias
- B. Effect modification
- C. Hawthorne effect
- D. Randomization failure
- E. Selection bias
Correct

Incorrect
Question 30 of 40

30. Question
A 65-year-old man is scheduled for hip replacement surgery. He is worried about possible complications of the surgery, particularly the risk of heart attack. A retrospective cohort study identified 98,102 patients who underwent total knee replacement (TKR) or total hip replacement (THR) surgery and compared their rates of myocardial infarction (MI) with those of controls matched by age, sex, and geographic region. The following curves for hazard ratios (HR) were obtained.

Based on the study results and assuming statistical significance, which of the following provides the best explanation to the patient?
- A. Although there is no risk of heart attack immediately following surgery, the risk increases after hospital discharge.
- B. There is an increased risk of heart attack after surgery, which is best explained by risk factors and comorbidities.
- C. There is an increased risk of heart attack right after surgery, but it returns to baseline after 4 weeks.
- D. There is an increased risk of heart attack up to approximately 8-10 weeks after the surgery.
- E. There is no substantial proof that the surgery is associated with a higher risk of heart attack.
Correct

Incorrect
Question 31 of 40

31. Question
A large-scale clinical trial was conducted to assess the effect of carvedilol (a mixed alpha- and beta-blocker) on the clinical course of New York Heart Association class III-IV chronic heart failure. The study reported that serum noradrenaline levels (a marker of the degree of neurohumoral activation) were correlated with serum sodium levels with correlation coefficient r = -0.39 (p = 0.005). Which of the following statements best describes the observed relationship between serum noradrenaline levels and serum sodium levels?
- A. Serum noradrenaline levels increase as serum sodium levels decrease
- B. Serum noradrenaline levels increase as serum sodium levels increase
- C. The measure of association does not reach statistical significance
- D. There is a strong correlation between serum noradrenaline and serum sodium levels
- E. Variations in serum noradrenaline levels change serum sodium levels
Correct

Incorrect
Question 32 of 40

32. Question
Title: Glutamine and antioxidants in critically ill patients

Hypothesis: Critically ill patients have considerable oxidative stress. Do glutamine and antioxidant supplementation offer therapeutic benefit in critically ill patients?

Methods:

Design: Randomized clinical trial.

Blinding: Double-blind placebo controlled.

Setting: Multicenter, 40 intensive care units (ICU) in Canada, the United States, and Europe.

Follow-up: 6 months.

Patients: Critically ill adults who had multiorgan failure and were receiving mechanical ventilation.

Intervention: Glutamine, antioxidants, both, or placebo.

Outcome measures: Mortality (primary outcome), time to discontinuation of mechanical ventilation and alive, time to discharge from ICU and alive, time to discharge from hospital and alive, ICU length of stay, hospital length of stay.

Results: A total of 1223 critically ill patients underwent randomization. The following outcomes are reported for all patients:

Conclusions: There is no overall benefit in supplementing glutamine or antioxidants to critically ill patients.

Funding Source: Canadian Institutes of Health Research.

Structured abstract is based on: NEJM 2013;368:1489-1497.

The abstract shown below applies to the next 2 items

A 56-year-old man is hospitalized in the intensive care unit due to community-acquired pneumonia with resultant multiorgan failure. His trachea is intubated and mechanical ventilation is initiated. His family wants to “do everything possible” to make him better and save his life.

Item 1 of 2

Based on the study results, which of the following is the best statement concerning the use of glutamine and antioxidants in this patient?
- A. It does not appear to be safe to use antioxidants in critically ill patients
- B. Mortality benefit should be balanced against longer hospital stay and associated costs
- C. Oxidative stress may not play an important role in critical illness
- D. There could be a marginal mortality benefit that is not clinically significant
- E. Use of glutamine may be associated with harm
Correct

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Question 33 of 40

33. Question
Title: Glutamine and antioxidants in critically ill patients

Hypothesis: Critically ill patients have considerable oxidative stress. Do glutamine and antioxidant supplementation offer therapeutic benefit in critically ill patients?

Methods:

Design: Randomized clinical trial.

Blinding: Double-blind placebo controlled.

Setting: Multicenter, 40 intensive care units (ICU) in Canada, the United States, and Europe.

Follow-up: 6 months.

Patients: Critically ill adults who had multiorgan failure and were receiving mechanical ventilation.

Intervention: Glutamine, antioxidants, both, or placebo.

Outcome measures: Mortality (primary outcome), time to discontinuation of mechanical ventilation and alive, time to discharge from ICU and alive, time to discharge from hospital and alive, ICU length of stay, hospital length of stay.

Results: A total of 1223 critically ill patients underwent randomization. The following outcomes are reported for all patients:

Conclusions: There is no overall benefit in supplementing glutamine or antioxidants to critically ill patients.

Funding Source: Canadian Institutes of Health Research.

Structured abstract is based on: NEJM 2013;368:1489-1497.

Item 2 of 2

The study randomized patients to glutamine, antioxidants, both, or placebo. Which of the following best describes the study design?
- A. Crossover
- B. Cross-sectional
- C. Factorial
- D. Nested
- E. Pragmatic
Correct

Incorrect
Question 34 of 40

34. Question
Objective

To evaluate the diagnostic accuracy of antigen Z testing for detecting prostate cancer.

Methods

Design: Observational study in community practice.

Participants: 2,600 men age ≥40 undergoing antigen Z testing and prostate biopsy in community practice.

Interventions: Antigen Z testing results were compared with a reference standard prostate biopsy.

Main outcome measures: The sensitivity and specificity were evaluated for various cut points of antigen Z (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20 ng/mL), and an area under the receiver operating characteristic (ROC) curve was created.

Results

An excerpt of study results is shown below.

Conclusion

Antigen Z testing had fair discriminating power for detecting prostate cancer in community practice.

The abstract shown on the left applies to the next 2 items.

Researchers are evaluating the diagnostic accuracy of different cut points for antigen Z in detecting prostate cancer.

Item 1 of 2

Based on the study results, which of the following describes the effect of changing the cut point from ≥4 ng/mL to ≥2 ng/mL?
- A. More individuals with prostate cancer will be missed
- B. More individuals without prostate cancer will be correctly identified as not having prostate cancer
- C. More individuals without prostate cancer will be incorrectly diagnosed with prostate cancer
- D. The change in cut point will have no effect on the performance of the test
Correct

Incorrect
Question 35 of 40

35. Question
Objective

To evaluate the diagnostic accuracy of antigen Z testing for detecting prostate cancer.

Methods

Design: Observational study in community practice.

Participants: 2,600 men age ≥40 undergoing antigen Z testing and prostate biopsy in community practice.

Interventions: Antigen Z testing results were compared with a reference standard prostate biopsy.

Main outcome measures: The sensitivity and specificity were evaluated for various cut points of antigen Z (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20 ng/mL), and an area under the receiver operating characteristic (ROC) curve was created.

Results

An excerpt of study results is shown below.

Conclusion

Antigen Z testing had fair discriminating power for detecting prostate cancer in community practice.

Item 2 of 2

Based on the study results, a cut point of ≥4 ng/mL has a positive likelihood ratio (LR+) of 1.31 and a negative likelihood ratio (LR−) of 0.43. Which of the following statements is true about LR+ and LR− of a cut point of ≥2 ng/mL compared to a cut point of ≥4 ng/mL?
- A. A cut point of ≥2 ng/mL has a slightly higher LR+ and LR−
- B. A cut point of ≥2 ng/mL has a slightly higher LR+ but slightly lower LR−
- C. A cut point of ≥2 ng/mL has a slightly lower LR+ and LR−
- D. A cut point of ≥2 ng/mL has a slightly lower LR+ but slightly higher LR−
Correct

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Question 36 of 40

36. Question
A study examines the role of different tumor markers or their combinations in diagnosing pancreatic cancer in patients with a solid lesion in the pancreatic head. The following table is reported:

Based on the study results, a patient with a solid lesion in the pancreatic head is most likely to be free of pancreatic cancer if which of the following tests or combinations is negative?
- A. Marker 1
- B. Marker 2
- C. Marker 3
- D. Parallel combination
- E. Serial combination
Correct

Incorrect
Question 37 of 40

37. Question
A randomized controlled study of chronically sleep-deprived (<6.5 hr per night), morbidly obese subjects examined whether sleep extension is associated with weight loss and metabolic and endocrinal improvements. The intervention consisted of education regarding sleep hygiene and a gradual change to subjects’ bedtimes to earlier in the evening. Participants underwent general screening at visit 1 with collection of baseline parameters; then, 2 months later, at visit 2, subjects were randomized into either an intervention group or a comparison group. Researchers evaluated several parameters, including sleep duration, sleepiness, and sleep quality. The following results were reported:

There were statistically significant differences in all 3 parameters between visit 1 and visit 2. Which of the following is the best explanation for the difference between findings at the screening and randomization visits?
- A. Allocation bias
- B. Confounding bias
- C. Hawthorne effect
- D. Placebo effect
- E. Selection bias
Correct

Incorrect
Question 38 of 40

38. Question
A retrospective, matched-cohort study is conducted to examine the effect of medical care provided by overnight physicians on the outcomes of their scheduled elective procedures performed during the day. Patients undergoing 1 of 5 elective daytime procedures performed by a physician who worked overnight were matched to patients undergoing the same procedure by the same physician on a day when the physician did not work overnight. The study outcome was a composite of patient death and complications. The study reported that the risk of the composite outcome was higher in patients who underwent a daytime procedure performed by a physician who had worked overnight compared to patients who underwent a procedure performed by a physician who had not worked overnight (22% vs. 20%, p = 0.04). Based on these results, what is the approximate percentage of deaths and complications that can be attributed to the physician having worked overnight before the scheduled elective procedures during the day?
- A. 1.1
- B. 9.1
- C. 22
- D. 50
Correct

Incorrect
Question 39 of 40

39. Question
A randomized controlled trial compared the effect of postoperative infusion of Drug X and Drug Y on the incidence of delirium in elderly patients undergoing major elective noncardiac surgery. A total of 560 patients age >65 undergoing major elective noncardiac surgery without a planned intensive care unit stay were randomly assigned to receive either Drug X (n = 280) or Drug Y (n = 280). The Drug Y group was the comparison group in the trial. The primary outcome was the incidence of delirium during the first 5 postoperative days. An excerpt of the study results is shown below.

Primary outcome

Drug X (n = 280)

Drug Y (n = 280)

p-value

Incidence of delirium, n (%)

14 (5.0)

28 (10.0)

0.025

Which of the following is the most accurate interpretation of these results as they relate to the development of delirium during the first 5 postoperative days in elderly patients undergoing major elective noncardiac surgery?
- A. About 20 patients need to be treated with Drug X to prevent an additional case of delirium when compared with Drug Y
- B. The absolute difference in the incidence of delirium with Drug X compared to Drug Y is 50%
- C. The ratio of the incidence of delirium with Drug X versus Drug Y is 2.0
- D. The relative decrease in the incidence of delirium with Drug X compared to Drug Y is 5%
Correct

Incorrect
Question 40 of 40

40. Question
Two independent research groups are studying the effect of a new anticoagulant on the incidence of deep-vein thrombosis after hip replacement surgery. The first group designs a 1:1 randomized trial with 1000 patients comparing the new drug with the standard of care (500 patients in each group). The second group designs a similar randomized trial but intends to recruit 500 patients (250 patients in each group). Assuming similar populations for patient recruitment, the small study has a higher chance of which of the following?
- A. Early termination
- B. Outcome misclassification
- C. Selection bias
- D. Type I error
- E. Type II error
Correct

Incorrect

Primary outcome	Drug X (n = 280)	Drug Y (n = 280)	p-value
Incidence of delirium, n (%)	14 (5.0)	28 (10.0)	0.025

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1. Question

2. Question

3. Question

The following vignette applies to the next 3 items

It is estimated that the prevalence of smoking in a population is 50%. A cohort study conducted using a random sample from this population showed that the 5-year risk of ischemic stroke is 1:1000 among smokers and 0.5:1000 among non-smokers.

Item 1 of 3

What is the relative risk of ischemic stroke among smokers compared to non-smokers?

4. Question

Item 2 of 3

What percentage of ischemic strokes observed in smokers can be attributed to their smoking status?

5. Question

Item 3 of 3

What percentage of ischemic strokes observed in the population can be attributed to smoking?

6. Question

The researchers included only studies 2, 3, and 5 in their meta-analysis. Which of the following statements concerning the possible results of the meta-analysis is most likely true?

7. Question

Administration of the combination pill resulted in a statistically significant sustained reduction in events for which of the following outcomes (setting α = 0.05)?

8. Question

The drug ad applies to the next 2 items.

The drug advertisement suggests that BoXeva should be added to metformin for the treatment of patients with type 2 diabetes mellitus.

Item 1 of 2 Compared to adding BoXeva, adding glimepiride to this patient’s current regimen will most likely lead to which of the following at 52 weeks of treatment?

9. Question

10. Question

11. Question

Abstract:

Hypothesis: There is an unmet need for effective dietary interventions to reduce the burden of gout. Dietary Approaches to Stop Hypertension (DASH) and Western diets show opposing associations with the risk of gout.

Methods:

Design: Prospective cohort study, 26 years of follow-up.

Participants: 44,444 men with no history of gout at baseline.

Outcome measures: Risk of incident gout fulfilling the preliminary survey criteria for gout by the American College of Rheumatology.

Results: The following data were reported for the incidence of gout according to fifths of DASH and Western dietary pattern scores:

All associations are statistically significant.

Of the 44,444 participants, 1,725 confirmed cases of incident gout were documented.

The abstract shown applies to the next 2 items.

Item 1 of 2

12. Question

Abstract:

Hypothesis: There is an unmet need for effective dietary interventions to reduce the burden of gout. Dietary Approaches to Stop Hypertension (DASH) and Western diets show opposing associations with the risk of gout.

Methods:

Design: Prospective cohort study, 26 years of follow-up.

Participants: 44,444 men with no history of gout at baseline.

Outcome measures: Risk of incident gout fulfilling the preliminary survey criteria for gout by the American College of Rheumatology.

Results: The following data were reported for the incidence of gout according to fifths of DASH and Western dietary pattern scores:

All associations are statistically significant.

Of the 44,444 participants, 1,725 confirmed cases of incident gout were documented.

Item 2 of 2

Based on the abstract, which of the following is true about the magnitude of the risk of gout among patients adopting a Western diet in the highest fifth as compared to patients adopting a Western diet in the lowest fifth?

13. Question

70% of the individual single-repetition maximum (1RM)

30% of the 1RM

30% of the 1RM with BFR (artificially applied by a cuff at 300 mm Hg)

14. Question

Title

Effect of vitamin D3 supplements on development of advanced cancer

Objective

To investigate whether vitamin D3 supplementation has an effect on advanced (metastatic or fatal) cancer among adults without a diagnosis of cancer at baseline.

Methods

Design: Randomized, placebo-controlled trial. Median intervention period of 5.3 years (range: 3.8-6.1 years).

Participants: 25,871 participants (51% female; mean [SD] age 67.1 [7.1]).

Exposure: Vitamin D3 (cholecalciferol 2,000 IU/d) or placebo; BMI (categorized as <25 kg/m2, 25-29 kg/m2, and ≥30 kg/m2).

Outcome: Incidence of any metastatic cancers and cancer mortality.

Results

In general, vitamin D3 was associated with a significant reduction in metastatic or fatal cancers compared with placebo (hazard ratio [HR]: 0.83, 95% confidence interval [CI]: 0.69-0.99). However, the associations were inconsistent across BMI levels.

Outcomes

Number of events in groups

HR† (95% CI)

Vitamin D3 (N = 12,927)

Placebo (N = 12,944)

Total metastatic cancer

BMI <25 kg/m2

24

39

0.63 (0.38-1.05)

BMI 25-29 kg/m2

Item 1 of 2
Compared to adding BoXeva, adding glimepiride to this patient’s current regimen will most likely lead to which of the following at 52 weeks of treatment?

Results:
The following data were reported for the incidence of gout according to fifths of DASH and Western dietary pattern scores:

Results:
The following data were reported for the incidence of gout according to fifths of DASH and Western dietary pattern scores:

Effect of vitamin D₃ supplements on development of advanced cancer

To investigate whether vitamin D₃ supplementation has an effect on advanced (metastatic or fatal) cancer among adults without a diagnosis of cancer at baseline.

Exposure: Vitamin D₃ (cholecalciferol 2,000 IU/d) or placebo; BMI (categorized as <25 kg/m², 25-29 kg/m², and ≥30 kg/m²).

In general, vitamin D₃ was associated with a significant reduction in metastatic or fatal cancers compared with placebo (hazard ratio [HR]: 0.83, 95% confidence interval [CI]: 0.69-0.99). However, the associations were inconsistent across BMI levels.

HR^† (95% CI)

Vitamin D₃
(N = 12,927)

Placebo
(N = 12,944)

BMI <25 kg/m²

BMI 25-29 kg/m²

BMI ≥30 kg/m²

BMI <25 kg/m²

BMI 25-29 kg/m²

BMI ≥30 kg/m²