1
, A new drug treatment for cardiac thrombus claims to have a higher success rate than the current
drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days
after treatment. 168 patients who require treatment for cardiac thrombi are randomized after
agreeing to participate in a trial of the new drug. The researchers were interested in whether the
new drug reduced the need for blood transfusions due to internal hemorrhage compared to the
current treatment. The following table summarizes the results of her study:
What is the incidence of needing a blood transfusion in the group of persons who were
randomized to the new drug treatment?
31.0%
41.1%
51.2%
62.3%
Incidence cannot be calculated with the information in this table
Explanation
Incidence is the development of the outcome under investigation among those at risk. In this
instance, 43 participants “developed” the need for a blood transfusion among the 84 persons in
the new drug treatment group.
Question
A new drug treatment for cardiac thrombus claims to have a higher success rate than the current
drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days
after treatment. 168 patients who require treatment for cardiac thrombi are randomized after
agreeing to participate in a trial of the new drug. The researchers were interested in whether the
new drug reduced the need for blood transfusions due to internal hemorrhage compared to the
current treatment. The following table summarizes the results of her study:
What is the number of persons who died in hospital in the study?
, 7
17
28
35
The number of deaths cannot be calculated as the death rate has not been age-adjusted
Explanation
The death rate in the study for all participants is 0.167. Multiplying this number by 168, the total
number of participants, results in 28 deaths in hospital following treatment.
Question
A new drug treatment for cardiac thrombus claims to have a higher success rate than the current
drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days
after treatment. 168 patients who require treatment for cardiac thrombi are randomized after
agreeing to participate in a trial of the new drug. The researchers were interested in whether the
new drug reduced the need for blood transfusions due to internal hemorrhage compared to the
current treatment. The following table summarizes the results of her study:
What is the main advantage of the randomization of the 168 study participants to one of the two
drug treatment groups?
Ensures that the researchers are masked to the treatment group assignment for each participant
Facilitates the age-adjustment of the death rate in each group
Reduces the potential for selection bias in allocation of treatment group
, Ensures that the study groups are comparable for characteristics such as age and severity of
condition prior to treatment assignment
Ensures that non-compliance will not affect the results
Explanation
Though the study is being conducted in a group of persons with a similar diagnosis, there should
be differences in age, gender, race, and severity of conditions in the 168 participants. In order to
ensure that those with a healthier profile are not preferentially selected for one of the treatment
groups, randomization is used.
Question
A new drug treatment for cardiac thrombus claims to have a higher success rate than the current
drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days
after treatment. 168 patients who require treatment for cardiac thrombi are randomized after
agreeing to participate in a trial of the new drug. The researchers were interested in whether the
new drug reduced the need for blood transfusions due to internal hemorrhage compared to the
current treatment. The following table summarizes the results of her study:
The researchers interpret the findings to conclude that the new drug treatment is more likely to
result in a blood transfusion and subsequent death. This statement is:
Incorrect as the data do not indicate the death rate among only those receiving a blood
transfusion
Incorrect as the number of expected deaths is not known
Incorrect as the cause-specific death rate for internal hemorrhaging is not reported
Incorrect as the duration of time from blood transfusion to death is not reported
Correct
Explanation
, A new drug treatment for cardiac thrombus claims to have a higher success rate than the current
drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days
after treatment. 168 patients who require treatment for cardiac thrombi are randomized after
agreeing to participate in a trial of the new drug. The researchers were interested in whether the
new drug reduced the need for blood transfusions due to internal hemorrhage compared to the
current treatment. The following table summarizes the results of her study:
What is the incidence of needing a blood transfusion in the group of persons who were
randomized to the new drug treatment?
31.0%
41.1%
51.2%
62.3%
Incidence cannot be calculated with the information in this table
Explanation
Incidence is the development of the outcome under investigation among those at risk. In this
instance, 43 participants “developed” the need for a blood transfusion among the 84 persons in
the new drug treatment group.
Question
A new drug treatment for cardiac thrombus claims to have a higher success rate than the current
drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days
after treatment. 168 patients who require treatment for cardiac thrombi are randomized after
agreeing to participate in a trial of the new drug. The researchers were interested in whether the
new drug reduced the need for blood transfusions due to internal hemorrhage compared to the
current treatment. The following table summarizes the results of her study:
What is the number of persons who died in hospital in the study?
, 7
17
28
35
The number of deaths cannot be calculated as the death rate has not been age-adjusted
Explanation
The death rate in the study for all participants is 0.167. Multiplying this number by 168, the total
number of participants, results in 28 deaths in hospital following treatment.
Question
A new drug treatment for cardiac thrombus claims to have a higher success rate than the current
drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days
after treatment. 168 patients who require treatment for cardiac thrombi are randomized after
agreeing to participate in a trial of the new drug. The researchers were interested in whether the
new drug reduced the need for blood transfusions due to internal hemorrhage compared to the
current treatment. The following table summarizes the results of her study:
What is the main advantage of the randomization of the 168 study participants to one of the two
drug treatment groups?
Ensures that the researchers are masked to the treatment group assignment for each participant
Facilitates the age-adjustment of the death rate in each group
Reduces the potential for selection bias in allocation of treatment group
, Ensures that the study groups are comparable for characteristics such as age and severity of
condition prior to treatment assignment
Ensures that non-compliance will not affect the results
Explanation
Though the study is being conducted in a group of persons with a similar diagnosis, there should
be differences in age, gender, race, and severity of conditions in the 168 participants. In order to
ensure that those with a healthier profile are not preferentially selected for one of the treatment
groups, randomization is used.
Question
A new drug treatment for cardiac thrombus claims to have a higher success rate than the current
drug. A strong sign of the potential success is the lack of internal hemorrhaging starting 2 days
after treatment. 168 patients who require treatment for cardiac thrombi are randomized after
agreeing to participate in a trial of the new drug. The researchers were interested in whether the
new drug reduced the need for blood transfusions due to internal hemorrhage compared to the
current treatment. The following table summarizes the results of her study:
The researchers interpret the findings to conclude that the new drug treatment is more likely to
result in a blood transfusion and subsequent death. This statement is:
Incorrect as the data do not indicate the death rate among only those receiving a blood
transfusion
Incorrect as the number of expected deaths is not known
Incorrect as the cause-specific death rate for internal hemorrhaging is not reported
Incorrect as the duration of time from blood transfusion to death is not reported
Correct
Explanation
