Number needed to treat/harm 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

A 33-year-old man is brought by ambulance to the emergency room after being a passenger in a motor vehicle accident. An empty bottle of whiskey was found in his front seat, and the patient admits to having been drinking all night. He has multiple lacerations and bruising on his face and scalp and a supportive cervical collar is placed. He is endorsing a significant headache and starts vomiting in the emergency room. His vitals, however, are stable, and he is transported to the CT scanner. While there, he states that he does not want to have a CT scan and asks to be released. What is the most appropriate course of action?

Accepted Answer

Explain to him that he is intoxicated and cannot make health care decisions, continue as planned

Answer

Have the patient fill the appropriate forms and discharge against medical advice

Answer

Release the patient as requested

Answer

Agree to not do the CT scan

Answer

Call security

Question 3

A 58-year-old man presents to the clinic concerned about his health after his elder brother recently became bed-bound due to a brain condition. He has also brought a head CT scan of his brother to reference, as shown in the picture. The patient has type 2 diabetes mellitus, hypertension, osteoarthritis, and hypercholesterolemia. His medication list includes aspirin, diclofenac sodium, metformin, and ramipril. He leads a sedentary lifestyle and smokes one pack of cigarettes daily. He also drinks 4–5 cups of red wine every weekend. His BMI is 33.2 kg/m2. His blood pressure is 164/96 mm Hg, the heart rate is 84/min, and the respiratory rate is 16/min. Which of the following interventions will be most beneficial for reducing the risk of developing the disease that his brother has?

Accepted Answer

Blood pressure control

Answer

Statin therapy

Answer

Quit smoking

Answer

Stop aspirin

Answer

Blood sugar control

Question 4

A 62-year-old man comes to the physician in May for a routine health maintenance examination. He feels well. He underwent a right inguinal hernia repair 6 months ago. He has hypertension and type 2 diabetes mellitus. There is no family history of serious illness. Current medications include metformin, sitagliptin, enalapril, and metoprolol. He received the zoster vaccine 1 year ago. He received the PPSV23 vaccine 4 years ago. His last colonoscopy was 7 years ago and was normal. He smoked a pack of cigarettes a day for 20 years but quit 17 years ago. He drinks two to three alcoholic beverages on weekends. He is allergic to amoxicillin. He is scheduled to visit Australia and New Zealand in 2 weeks to celebrate his 25th wedding anniversary. He appears healthy. Vital signs are within normal limits. An S4 is heard at the apex. The remainder of the examination shows no abnormalities. Which of the following is the most appropriate recommendation at this time?

Accepted Answer

Influenza vaccine

Answer

Colonoscopy

Answer

Pneumococcal conjugate vaccine 13

Answer

Cardiac stress test

Answer

Abdominal ultrasound

Question 5

A research team is studying the effects of a novel drug that was discovered to treat type 2 diabetes. In order to learn more about its effects, they follow patients who are currently taking the drug and determine whether there are adverse effects that exceed anticipated levels and may therefore be drug-related. They discover that the drug causes an excess of sudden cardiac death in 19 patients with renal failure out of 2 million total patients that are followed. Based on these results, an additional warning about this serious adverse effect is added to the investigator brochure for the drug. Which of the following clinical phase studies does this study most likely describe?

Accepted Answer

Phase IV

Answer

Phase II

Answer

Phase V

Answer

Phase III

Answer

Phase I

Question 6

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 7

A 57-year-old man presents to his oncologist to discuss management of small cell lung cancer. The patient is a lifelong smoker and was diagnosed with cancer 1 week ago. The patient states that the cancer was his fault for smoking and that there is "no hope now." He seems disinterested in discussing the treatment options and making a plan for treatment and followup. The patient says "he does not want any treatment" for his condition. Which of the following is the most appropriate response from the physician?

Accepted Answer

"It must be very challenging having received this diagnosis. I want to work with you to create a plan."

Answer

"You seem upset at the news of this diagnosis. I want you to go home and discuss this with your loved ones and come back when you feel ready to make a plan together for your care."

Answer

"It must be tough having received this diagnosis; however, new cancer therapies show increased efficacy and excellent outcomes."

Answer

"We are going to need to treat your lung cancer. I am here to help you throughout the process."

Answer

"I respect your decision and we will not administer any treatment. Let me know if I can help in any way."

Question 8

A student health coordinator plans on leading a campus-wide HIV screening program that will be free for the entire undergraduate student body. The goal is to capture as many correct HIV diagnoses as possible with the fewest false positives. The coordinator consults with the hospital to see which tests are available to use for this program. Test A has a sensitivity of 0.92 and a specificity of 0.99. Test B has a sensitivity of 0.95 and a specificity of 0.96. Test C has a sensitivity of 0.98 and a specificity of 0.93. Which of the following testing schemes should the coordinator pursue?

Accepted Answer

Test C on the entire student body followed by Test A on those who are positive

Answer

Test A on the entire student body followed by Test B on those who are positive

Answer

Test A on the entire student body followed by Test C on those who are positive

Answer

Test C on the entire student body followed by Test B on those who are positive

Answer

Test B on the entire student body followed by Test A on those who are positive

Question 9

In 2006, three researchers from North Carolina wanted to examine the benefits of treating the risk of suicidality in children and adolescents by looking at randomized, multicenter, controlled trials of sertraline usage compared to placebo. Their analysis found clinically significant benefits of the drug and a positive benefit-to-risk ratio for sertraline in adolescents with major depressive disorder. They also found that 64 depressed children and adolescents need to receive the drug for 1 extra patient to experience suicidality as an adverse outcome. In other words, if 64 treated individuals received sertraline, some would experience suicidality due to their illness, some would not experience suicidality, and 1 individual would become suicidal due to the unique contribution of sertraline. Which of the following statements is true for this measure (defined as the inverse of the attributable risk), which aims to describe adverse outcomes this way?

Accepted Answer

Input values must be probabilities of the events of interest.

Answer

Higher measures indicate greater risk.

Answer

Multiple risks can be contained and described within one result.

Answer

The final metric represents proportions in percentage terms.

Answer

The measure can include multiple events at one time.

Question 10

A survey was conducted in a US midwestern town in an effort to assess maternal mortality over the past year. The data from the survey are given in the table below:
Women of childbearing age 250,000
Maternal deaths 2,500
Number of live births 100, 000
Number of deaths of women of childbearing age 7,500
Maternal death is defined as the death of a woman while pregnant or within 42 days of termination of pregnancy from any cause related to or aggravated by, the pregnancy. Which of the following is the maternal mortality rate in this midwestern town?

Accepted Answer

2,500 per 100,000 live births

Answer

1,000 per 100,000 live births

Answer

33 per 100,000 live births

Answer

3,000 per 100,000 live births

Answer

33,300 per 100,000 live births

Number needed to treat/harm

Study Resources

Lessons

Questions

Flashcards

Lessons

Definition of NNT/NNH

Calculation from absolute risk reduction

Interpretation and clinical application

Confidence intervals for NNT/NNH

Relationship with relative risk reduction

Time-dependent NNT

NNT in prevention vs treatment

NNT in screening programs

Cost-effectiveness and NNT

Limitations and common misinterpretations

Reporting in clinical guidelines

Comparing interventions using NNT

Practice Questions

Flashcards

About Number needed to treat/harm for USMLE

Lessons in Number needed to treat/harm

Master Number needed to treat/harm