Odds ratio vs. relative risk Practice Questions

Question 1

A research team develops a new monoclonal antibody checkpoint inhibitor for advanced melanoma that has shown promise in animal studies as well as high efficacy and low toxicity in early phase human clinical trials. The research team would now like to compare this drug to existing standard of care immunotherapy for advanced melanoma. The research team decides to conduct a non-randomized study where the novel drug will be offered to patients who are deemed to be at risk for toxicity with the current standard of care immunotherapy, while patients without such risk factors will receive the standard treatment. Which of the following best describes the level of evidence that this study can offer?

Accepted Answer

Level 3

Answer

Level 1

Answer

Level 5

Answer

Level 4

Answer

Level 2

Question 2

You are conducting a study comparing the efficacy of two different statin medications. Two groups are placed on different statin medications, statin A and statin B. Baseline LDL levels are drawn for each group and are subsequently measured every 3 months for 1 year. Average baseline LDL levels for each group were identical. The group receiving statin A exhibited an 11 mg/dL greater reduction in LDL in comparison to the statin B group. Your statistical analysis reports a p-value of 0.052. Which of the following best describes the meaning of this p-value?

Accepted Answer

There is a 5.2% chance of observing a difference in reduction of LDL of 11 mg/dL or greater even if the two medications have identical effects

Answer

There is a 95% chance that the difference in reduction of LDL observed reflects a real difference between the two groups

Answer

Though A is more effective than B, there is a 5% chance the difference in reduction of LDL between the two groups is due to chance

Answer

If 100 permutations of this experiment were conducted, 5 of them would show similar results to those described above

Answer

This is a statistically significant result

Question 3

A 25-year-old man with a genetic disorder presents for genetic counseling because he is concerned about the risk that any children he has will have the same disease as himself. Specifically, since childhood he has had difficulty breathing requiring bronchodilators, inhaled corticosteroids, and chest physiotherapy. He has also had diarrhea and malabsorption requiring enzyme replacement therapy. If his wife comes from a population where 1 in 10,000 people are affected by this same disorder, which of the following best represents the likelihood a child would be affected as well?

Accepted Answer

1%

Answer

0.01%

Answer

2%

Answer

0.5%

Answer

50%

Question 4

A 45-year-old man comes to the clinic concerned about his recent exposure to radon. He heard from his co-worker that radon exposure can cause lung cancer. He brings in a study concerning the risks of radon exposure. In the study, there were 300 patients exposed to radon, and 18 developed lung cancer over a 10-year period. To compare, there were 500 patients without radon exposure and 11 developed lung cancer over the same 10-year period. If we know that 0.05% of the population has been exposed to radon, what is the attributable risk percent for developing lung cancer over a 10 year period after radon exposure?

Accepted Answer

63.3%

Answer

3.8%

Answer

0.31%

Answer

2.2%

Answer

6.0%

Question 5

You are reading through a recent article that reports significant decreases in all-cause mortality for patients with malignant melanoma following treatment with a novel biological infusion. Which of the following choices refers to the probability that a study will find a statistically significant difference when one truly does exist?

Accepted Answer

Power

Answer

Type II error

Answer

Type I error

Answer

Confidence interval

Answer

p-value

Question 6

A physician attempts to study cirrhosis in his state. Using a registry of admitted patients over the last 10 years at the local hospital, he isolates all patients who have been diagnosed with cirrhosis. Subsequently, he contacts this group of patients, asking them to complete a survey assessing their prior exposure to alcohol use, intravenous drug abuse, blood transfusions, personal history of cancer, and other medical comorbidities. An identical survey is given to an equal number of patients in the registry who do not carry a prior diagnosis of cirrhosis. Which of the following is the study design utilized by this physician?

Accepted Answer

Case-control study

Answer

Randomized controlled trial

Answer

Cross-sectional study

Answer

Cohort study

Answer

Meta-analysis

Question 7

A medical research study is beginning to evaluate the positive predictive value of a novel blood test for non-Hodgkin’s lymphoma. The diagnostic arm contains 700 patients with NHL, of which 400 tested positive for the novel blood test. In the control arm, 700 age-matched control patients are enrolled and 0 are found positive for the novel test. What is the PPV of this test?

Accepted Answer

400 / (400 + 0)

Answer

700 / (700 + 300)

Answer

400 / (400 + 300)

Answer

700 / (700 + 0)

Answer

700 / (400 + 400)

Question 8

You are currently employed as a clinical researcher working on clinical trials of a new drug to be used for the treatment of Parkinson's disease. Currently, you have already determined the safe clinical dose of the drug in a healthy patient. You are in the phase of drug development where the drug is studied in patients with the target disease to determine its efficacy. Which of the following phases is this new drug currently in?

Accepted Answer

Phase 2

Answer

Phase 4

Answer

Phase 1

Answer

Phase 0

Answer

Phase 3

Question 9

The height of American adults is expected to follow a normal distribution, with a typical male adult having an average height of 69 inches with a standard deviation of 0.1 inches. An investigator has been informed about a community in the American Midwest with a history of heavy air and water pollution in which a lower mean height has been reported. The investigator plans to sample 30 male residents to test the claim that heights in this town differ significantly from the national average based on heights assumed be normally distributed. The significance level is set at 10% and the probability of a type 2 error is assumed to be 15%. Based on this information, which of the following is the power of the proposed study?

Accepted Answer

0.85

Answer

0.10

Answer

0.90

Answer

0.15

Answer

0.05

Question 10

A population is studied for risk factors associated with testicular cancer. Alcohol exposure, smoking, dietary factors, social support, and environmental exposure are all assessed. The researchers are interested in the incidence and prevalence of the disease in addition to other outcomes. Which pair of studies would best assess the 1. incidence and 2. prevalence?

Accepted Answer

1. Prospective cohort study 2. Cross sectional study

Answer

1. Prospective cohort study 2. Retrospective cohort study

Answer

1. Cross sectional study 2. Retrospective cohort study

Answer

1. Case-control study 2. Prospective cohort study

Answer

1. Clinical trial 2. Cross sectional study

Odds ratio vs. relative risk

Study Resources

Lessons

Questions

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Lessons

Definition and calculation of odds ratio

Definition and calculation of relative risk

Interpretation differences

When odds ratio approximates relative risk

Common misinterpretations

Application in different study designs

Adjusted odds ratios

Confidence intervals for OR and RR

Reporting in medical literature

Absolute risk vs relative measures

Number needed to treat relation

Meta-analysis of odds ratios and relative risks

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