Question

Question 1.

The main purpose of screening is to identify symptomatic disease using tests, exams, or other procedures.

True

False

Question 2.

The detectable pre-clinical phase of a disease starts when the disease can be identified by a screening test and ends when the disease produces symptoms.

True

False

Question 3

.Diseases that are appropriate for screening…

	a.	Have serious consequences
	b.	Have a treatment that is more effective at an earlier stage
	c.	Have a detectable preclinical phase that is fairly common in the target population
	d.	All of the above

Question 4

Use the following information to answer questions 4-8. Suppose that 50,000 women who have never had a breast cancer diagnosis are available and willing to participate in a new screening program of computerized digital mammography. 1132 women had a positive screening test. All of these positive women had a breast biopsy and 136 were diagnosed with breast cancer. Of the 48,868 who screened “negative” on the test, 24 were in fact in the detectable pre-clinical phase. This was determined by following these women and observing that all 24 were diagnosed with breast cancer within one year of the screening test.

What is the prevalence of the detectable pre-clinical phase of breast cancer in this population?

	a.	136/50,000
	b.	160/50,000
	c.	1,132/50,000

Question 5

Use the following information to answer questions 4-8. Suppose that 50,000 women who have never had a breast cancer diagnosis are available and willing to participate in a new screening program of computerized digital mammography. 1132 women had a positive screening test. All of these positive women had a breast biopsy and 136 were diagnosed with breast cancer. Of the 48,868 who screened “negative” on the test, 24 were in fact in the detectable pre-clinical phase. This was determined by following these women and observing that all 24 were diagnosed with breast cancer within one year of the screening test.

What is the sensitivity of this new screening test?

	a.	12%
	b.	85%
	c.	98%
	d.	99.9%

Question 6

Use the following information to answer questions 4-8. Suppose that 50,000 women who have never had a breast cancer diagnosis are available and willing to participate in a new screening program of computerized digital mammography. 1132 women had a positive screening test. All of these positive women had a breast biopsy and 136 were diagnosed with breast cancer. Of the 48,868 who screened “negative” on the test, 24 were in fact in the detectable pre-clinical phase. This was determined by following these women and observing that all 24 were diagnosed with breast cancer within one year of the screening test.

What is the specificity of this new screening test?

	a.	12%
	b.	85%
	c.	98%
	d.	99.9%

Question 7

Use the following information to answer questions 4-8. Suppose that 50,000 women who have never had a breast cancer diagnosis are available and willing to participate in a new screening program of computerized digital mammography. 1132 women had a positive screening test. All of these positive women had a breast biopsy and 136 were diagnosed with breast cancer. Of the 48,868 who screened “negative” on the test, 24 were in fact in the detectable pre-clinical phase. This was determined by following these women and observing that all 24 were diagnosed with breast cancer within one year of the screening test.

What is the predictive value of a positive test result for this new screening test?

	a.	12%
	b.	85%
	c.	98%
	d.	99.9%

Question 8

Use the following information to answer questions 4-8. Suppose that 50,000 women who have never had a breast cancer diagnosis are available and willing to participate in a new screening program of computerized digital mammography. 1132 women had a positive screening test. All of these positive women had a breast biopsy and 136 were diagnosed with breast cancer. Of the 48,868 who screened “negative” on the test, 24 were in fact in the detectable pre-clinical phase. This was determined by following these women and observing that all 24 were diagnosed with breast cancer within one year of the screening test.

A colleague in another city reports that the same screening test (with the same sensitivity and specificity) is achieving a predictive value positive of only 6%. What is the explanation for this?

	a.	The colleague is screening a higher risk population
	b.	The colleague is screening a lower risk population
	c.	The colleague is screening a larger population
	d.	The colleague is screening a smaller population

Question 9

Lead time bias makes it erroneously appear that survival is better for screened versus unscreened cases.

True

False

Question 10

Length bias occurs because fast growing tumors are more likely to be picked up by a screening test than are slow growing tumors.

True

False

Question 11

What is the correct interpretation of the results of a calculation of specificity for a screening test of 97%?

	a.	The test is able to correctly classify as positive 97% of those with the disease.
	b.	The test is able to correctly classify as negative 97% of those without the disease.
	c.	Of those who screened positive, 97% of them actually have the disease.
	d.	Of those who screened negative, 97% of them actually do not have the disease.

Question 12

The difference between primary and secondary prevention of disease is:

	a.	Primary prevention means control of causal factors, while secondary prevention means control of disease progression.
	b.	Primary prevention means control of acute disease, while secondary prevention means control of chronic disease.
	c.	Primary prevention means control of causal factors, while secondary prevention means early detection and treatment of disease.
	d.	Primary prevention means increasing resistance to disease, while secondary prevention means decreasing exposure to disease.

Question 13

Sensitivity refers to the ability of a screening test to identify correctly all screened individuals who have a disease.

True

False

Question 14

Sensitivity and specificity of a screening test refer to its:

	a.	Reliability
	b.	Validity
	c.	Repeatability
	d.	All of the above

1.7 points

Question 15

If the same screening test is conducted in two populations, one with a high prevalence of the disease and one with a low prevalence of the disease, assuming the sensitivity and specificity of the screening test are the same, which of the following statements about positive predictive value (PPV) applies:

	a.	PPV is higher in the screened population with higher prevalence
	b.	PPV is lower in the screened population with higher prevalence
	c.	PPV is the same in both populations
	d.	It cannot be determined

Answer 1

Sensitivity and specificity of a screening test refers to its

a) Reliability

b) Validity

c) Repeatability

d) all the abobe

ans:-

Sensitivity is the ability of the test to correctly identify those who have the disease.

Specificity is the ability of the test to correctly identify the percentage of those who do not have the disease.

here the answer is B

Validity is determined by the sensitivity and specificity of the test.

The difference between primary and secondary prevention of disease is