Sensitivity refers to: Answer The ability of a screening test to correctly ident
ID: 3171525 • Letter: S
Question
Sensitivity refers to:
Answer
The ability of a screening test to correctly identify those screened individuals who have the disease
The ability of a screening test to identify no diseased individuals who actually do not have the disease
The ability of a measuring instrument to give consistent results on repeated trials, regardless of its accuracy
The proportion of those screened positive who actually have the disease
2 points
Question 2
A screening examination was performed on 550 persons for Factor X, which is found in disease Y. A definitive diagnosis for disease Y had been obtained previously. The prevalence of the condition was 10% in the population and the results of the screening are shown in the table below. Please use the table for questions 2 through 6:
Disease Status
TEST RESULTS
Disease Y Present
Disease Y Absent
Positive for Factor X
40
50
Negative for Factor X
10
450
The sensitivity of this test is:Answer
10%
44%
80%
90%
98%
2 points
Question 3
The specificity of this test is:
Answer
10%
44%
80%
90%
98%
2 points
Question 4
The positive predictive value of this test is:
Answer
10%
44%
80%
90%
98%
2 points
Question 5
The negative predictive value of this test is:
Answer
10%
44%
80%
90%
98%
2 points
Question 6
The number of false positives in this screened population is:
Answer
10
50
460
90
2 points
Question 7
Had the prevalence of the condition Y in this population of 500 been 25% instead of 10% and the sensitivity and specificity of the screening test remained unchanged, what would have been observed with the positive predictive value?
Answer
It would decrease
It would increase
It would remain unchanged
It cannot be determined
2 points
Question 8
Use of sequential screening in which only those who test positive to the first test are administered the second test generally results in:
Answer
A gain in net specificity
A gain in net sensitivity
A decrease in net sensitivity
An increase in both sensitivity and specificity
2 points
Question 9
Lead time bias is:
Answer
A bias that occurs because screening tends to identify cases with less aggressive forms of the disease
An actually longer survival time for persons identified during a screening program because they were given an effective treatment
An apparently lower survival rate among persons screened compared to an unscreened group
An apparently longer survival time among persons identified during a screening program because they were identified at an earlier stage of their disease
2 points
Question 10
Length-bias can be described as:
Answer
A bias that occurs because screening tends to identify cases with less aggressive forms of the disease
An actually longer survival time for persons identified during a screening program because they were given an effective treatment
An apparently lower survival rate among persons screened compared to an unscreened group
An apparently longer survival time among persons identified during a screening program because they were identified at an earlier stage of their disease
2 points
Question 11
This form of bias may appear to indicate an increase in incidence of the condition that can be attributed to an increase in the number of false positives.
Answer
Lead time bias
Volunteer bias
overdiagnosis bias
A prognostic selection bias
2 points
Question 12
A screening test for HIV had sensitivity of 99% and specificity of 90%. When used in a drug abuse clinic the test was found to have a positive predictive value of 85%. When used to screen a group of blood donors, the test was found to have a positive predictive value of 30%. Which of the following best explains this difference between the positive predictive values?
Answer
Measurement error
The prevalence of HIV is higher among those in the drug abuse clinic than among blood donors
Cases of HIV are more severe among those in the drug abuse clinic
Interobserver variation
2 points
Question 13
Conditions favorable to population screening for presymptomatic diagnosis of a given disease include:
Answer
A relatively high prevalence of the disease
Availability of effective treatment
A screening test with a high degree of sensitivity
All of the above
2 points
Question 14
Adverse consequences of using a screening test that has a low specificity include:
Answer
Unnecessarily subjecting people to a potential risk associated with diagnostic procedures
Possible psychological trauma that accompanies suspicion of a disease
Both of the above
Neither of the above
2 points
Question 15
A new test has been developed to screen for a particular disease. Initially a test result of X or higher was considered positive for the disease. Researchers determined that the sensitivity of the test was unacceptably low. To increase the test's sensitivity, it would be possible to:
Answer
Lower the minimum test result below X
Raise the minimum test result above X
Use a population with a higher prevalence of the disease
None of the above
Question 16
What would the effect be on the specificity of the test if the sensitivity is increased?
Answer
Specificity would remain the same
Specificity would increase
Specificity would decrease
It is uncertain what the effect would be on the specificity with the information provid
The ability of a screening test to correctly identify those screened individuals who have the disease
The ability of a screening test to identify no diseased individuals who actually do not have the disease
The ability of a measuring instrument to give consistent results on repeated trials, regardless of its accuracy
The proportion of those screened positive who actually have the disease
Explanation / Answer
Result: multiple questions: 1-7 answered
Sensitivity refers to:
Answer
Answer: The ability of a screening test to correctly identify those screened individuals who have the disease
The ability of a screening test to identify no diseased individuals who actually do not have the disease
The ability of a measuring instrument to give consistent results on repeated trials, regardless of its accuracy
The proportion of those screened positive who actually have the disease
2 points
Question 2
A screening examination was performed on 550 persons for Factor X, which is found in disease Y. A definitive diagnosis for disease Y had been obtained previously. The prevalence of the condition was 10% in the population and the results of the screening are shown in the table below. Please use the table for questions 2 through 6:
Disease Status
TEST RESULTS
Disease Y Present
Disease Y Absent
Positive for Factor X
40
50
Negative for Factor X
10
450
The sensitivity of this test is:Answer
10%
44%
Answer: 80%
90%
98%
2 points
Question 3
The specificity of this test is:
Answer
10%
44%
80%
Answer: 90%
98%
2 points
Question 4
The positive predictive value of this test is:
Answer
10%
Answer: 44%
80%
90%
98%
2 points
Question 5
The negative predictive value of this test is:
Answer
10%
44%
80%
90%
Answer: 98%
2 points
Question 6
The number of false positives in this screened population is:
Answer
10
Answer: 50
460
90
2 points
Question 7
Had the prevalence of the condition Y in this population of 500 been 25% instead of 10% and the sensitivity and specificity of the screening test remained unchanged, what would have been observed with the positive predictive value?
Answer
It would decrease
Answer: It would increase
It would remain unchanged
It cannot be determined
Answer: The ability of a screening test to correctly identify those screened individuals who have the disease
The ability of a screening test to identify no diseased individuals who actually do not have the disease
The ability of a measuring instrument to give consistent results on repeated trials, regardless of its accuracy
The proportion of those screened positive who actually have the disease
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