Biostats – NAPLEX UPDATED ACTUAL
Questions and CORRECT Answers
Question
What is the term used for the inactive or inert substance that is administered to a patient in a
trial and used to compare the effects of a real drug or other intervention?
Answer
A
The excipient
B
The standard deviation
C
The null hypothesis
D
The placebo
E
The desiccant - CORRECT ANSWER- d
Placebos are used in clinical trials to blind people to their treatment allocation and minimize
bias. Placebos should be indistinguishable from the active intervention to ensure adequate
blinding.
Question
Choose the categories that represent direct medical costs: (Select ALL that apply.)
Answer
A
Cost of a prescription
B
Travel costs
,C
Cost of a surgery
D
Cost of hospitalization
E
Pain and suffering - CORRECT ANSWER- acd
The cost of drugs, the cost of surgery and cost of hospitalization are all examples of direct
costs.
Question
A pharmacist is presenting the Helsinki trial which investigated gemfibrozil 1,200 mg daily
versus control. The results showed that CHD events were 2.7% in the gemfibrozil arm versus
4.1% in the control group, with a p-value of < 0.02. What is the number needed to treat to
prevent one CHD event in this trial?
Answer - CORRECT ANSWER- 72
Number needed to treat (NNT) is 1/ARR. Therefore, 1/0.014 = 72 patients. 72 patients will
need to be treated with gemfibrozil to prevent one CHD event. calculate ARR (convert
percent to nonpercent): 0.041 (control outcome) - 0.027 (experimental outcome) = 0.014. To
calculate NNT: 1/0.014 = 71.4 need to round up to 72 (can't treat 71.4 people)
A pharmacy intern has been asked by his preceptor to gather 200 discharged patient charts
from the chart room. He has been told that half the charts should be patients who received
proton pump inhibitor (PPI) therapy while hospitalized. The other half should be patients
with similar conditions and length of stay but who did not receive PPI therapy. The
pharmacist wishes to conduct a study to see if there is any difference in the incidence of
nosocomial infection in the PPI group versus the non-PPI group. Which of the following
describes this type of study? (Select ALL that apply.)
Answer
A
Cohort study
,B
Meta analysis
C
Case-control study
D
Randomized controlled trial
E
Observational study - CORRECT ANSWER- ae
A cohort study is a type of observational study (there is no intervention). This study describes
a retrospective cohort (the cohort is discharged patients). These patients are then evaluated to
determine if they were receiving PPIs, and then the outcome of nosocomial pneumonia is
assessed. To be a case-control study, one would need to start out by identifying the outcome
(the patients who developed pneumonia) which was not done at the onset of the study.
A researcher gathered all vitamin E studies from the past ten years. Vitamin E was used for a
variety of conditions. The populations studied as well as the vitamin E formulations and
doses were all different. However, the researcher did the best he could and compared the
incidences of cardiovascular-related mortality in those taking vitamin E supplements versus
those that did not. Describe this type of study:
Answer
A
Case series
B
Case-control study
C
Cohort study
D
Randomized controlled trial
E
Meta analysis - CORRECT ANSWER- e
, A meta analysis is a systematic review of many different but related studies in order to
integrate the results. These are often done and can be useful to pool smaller trials into a larger
group for analysis (e.g., Cochrane reviews).
Question
The pharmacist is presenting a clinical trial to the medical team. The trial includes a 95%
confidence interval for the primary endpoint. If the confidence interval was greater (98% or
99%), what effect will be seen with the interval?
Answer
A
The interval will be wider.
B
The interval will be more narrow.
C
There will be no effect on the interval.
D
The interval will no longer have valid meaning at a greater confidence level.
E
It will cause the p-value to be invalid. - CORRECT ANSWER- a
The range of numbers will be bigger if the confidence interval is higher. For example, to be
99% confident that the true value for the population falls in the range, the interval will be
wider (e.g., closer to 3 SD from the mean) than a 95% confidence interval (where the values
fall within 2 SD of the mean). Applied to a clinical scenario, if the 95% confidence interval
for decrease in A1C is 2-3% (meaning you are 95% confident that all patients will have a
decrease in A1C between 2-3%), then your range will need to be bigger (e.g., 4-6%) to be
99% confident of the decrease in A1C experienced by all patients. This concept should not be
confused with precision of the data as discussed on page 189-190 of the 2018 RxPrep Course
Book.
A pharmacist is considering which beta blocker should be preferred at his institution. He has
narrowed his search down to two agents. Each drug provides similar health benefits, has
similar tolerability and is dosed once daily. The pharmacist will base his decision on the drug
that can be purchased at the lower cost. He will use the following analysis to choose the beta
blocker for his institution's formulary:
Questions and CORRECT Answers
Question
What is the term used for the inactive or inert substance that is administered to a patient in a
trial and used to compare the effects of a real drug or other intervention?
Answer
A
The excipient
B
The standard deviation
C
The null hypothesis
D
The placebo
E
The desiccant - CORRECT ANSWER- d
Placebos are used in clinical trials to blind people to their treatment allocation and minimize
bias. Placebos should be indistinguishable from the active intervention to ensure adequate
blinding.
Question
Choose the categories that represent direct medical costs: (Select ALL that apply.)
Answer
A
Cost of a prescription
B
Travel costs
,C
Cost of a surgery
D
Cost of hospitalization
E
Pain and suffering - CORRECT ANSWER- acd
The cost of drugs, the cost of surgery and cost of hospitalization are all examples of direct
costs.
Question
A pharmacist is presenting the Helsinki trial which investigated gemfibrozil 1,200 mg daily
versus control. The results showed that CHD events were 2.7% in the gemfibrozil arm versus
4.1% in the control group, with a p-value of < 0.02. What is the number needed to treat to
prevent one CHD event in this trial?
Answer - CORRECT ANSWER- 72
Number needed to treat (NNT) is 1/ARR. Therefore, 1/0.014 = 72 patients. 72 patients will
need to be treated with gemfibrozil to prevent one CHD event. calculate ARR (convert
percent to nonpercent): 0.041 (control outcome) - 0.027 (experimental outcome) = 0.014. To
calculate NNT: 1/0.014 = 71.4 need to round up to 72 (can't treat 71.4 people)
A pharmacy intern has been asked by his preceptor to gather 200 discharged patient charts
from the chart room. He has been told that half the charts should be patients who received
proton pump inhibitor (PPI) therapy while hospitalized. The other half should be patients
with similar conditions and length of stay but who did not receive PPI therapy. The
pharmacist wishes to conduct a study to see if there is any difference in the incidence of
nosocomial infection in the PPI group versus the non-PPI group. Which of the following
describes this type of study? (Select ALL that apply.)
Answer
A
Cohort study
,B
Meta analysis
C
Case-control study
D
Randomized controlled trial
E
Observational study - CORRECT ANSWER- ae
A cohort study is a type of observational study (there is no intervention). This study describes
a retrospective cohort (the cohort is discharged patients). These patients are then evaluated to
determine if they were receiving PPIs, and then the outcome of nosocomial pneumonia is
assessed. To be a case-control study, one would need to start out by identifying the outcome
(the patients who developed pneumonia) which was not done at the onset of the study.
A researcher gathered all vitamin E studies from the past ten years. Vitamin E was used for a
variety of conditions. The populations studied as well as the vitamin E formulations and
doses were all different. However, the researcher did the best he could and compared the
incidences of cardiovascular-related mortality in those taking vitamin E supplements versus
those that did not. Describe this type of study:
Answer
A
Case series
B
Case-control study
C
Cohort study
D
Randomized controlled trial
E
Meta analysis - CORRECT ANSWER- e
, A meta analysis is a systematic review of many different but related studies in order to
integrate the results. These are often done and can be useful to pool smaller trials into a larger
group for analysis (e.g., Cochrane reviews).
Question
The pharmacist is presenting a clinical trial to the medical team. The trial includes a 95%
confidence interval for the primary endpoint. If the confidence interval was greater (98% or
99%), what effect will be seen with the interval?
Answer
A
The interval will be wider.
B
The interval will be more narrow.
C
There will be no effect on the interval.
D
The interval will no longer have valid meaning at a greater confidence level.
E
It will cause the p-value to be invalid. - CORRECT ANSWER- a
The range of numbers will be bigger if the confidence interval is higher. For example, to be
99% confident that the true value for the population falls in the range, the interval will be
wider (e.g., closer to 3 SD from the mean) than a 95% confidence interval (where the values
fall within 2 SD of the mean). Applied to a clinical scenario, if the 95% confidence interval
for decrease in A1C is 2-3% (meaning you are 95% confident that all patients will have a
decrease in A1C between 2-3%), then your range will need to be bigger (e.g., 4-6%) to be
99% confident of the decrease in A1C experienced by all patients. This concept should not be
confused with precision of the data as discussed on page 189-190 of the 2018 RxPrep Course
Book.
A pharmacist is considering which beta blocker should be preferred at his institution. He has
narrowed his search down to two agents. Each drug provides similar health benefits, has
similar tolerability and is dosed once daily. The pharmacist will base his decision on the drug
that can be purchased at the lower cost. He will use the following analysis to choose the beta
blocker for his institution's formulary:
