B5-073 EBM: Colon Cancer Screening

Question 1

number one risk factor for colorectal cancer

Answer 1

age

Question 2

risk factors for colon cancer

4

Answer 2

• age
• history of CRC or polyps
• Lynch syndrome
• hx of inflammatory bowel disease

Question 3

decreasing incidence and mortality due to colon cancer is due to

Answer 3

• detection of early stage cancer
• removal of precancerous polyps

Question 4

USPSTF grade A recommendation for CRC screening

ages

Answer 4

50-75

Question 5

USPSTF grade B recommendation for CRC screening

ages

Answer 5

45-49

Question 6

USPSTF grade C recommendation for CRC screening

ages

Answer 6

76-85

Question 7

choices for screening tests

4

Answer 7

stool test at home
colonoscopy
sigmoidoscopy
CT colonography

Question 8

PICO

Answer 8

population
intervention
control
outcome

Question 9

clusters of individuals are randomly allocated to intervention group

Answer 9

cluster randomization

Question 10

positive predictive value is dependent on

Answer 10

prevalence

Question 11

the more sensitive a test, the higher the incidence of

Answer 11

false positive

Question 12

what test performance characteristic are risk-based screening recommendations looking to improve?

Answer 12

positive predictive value

Question 13

• plots the true positive rate (sensitivity) on the y axis
• and the false positive rate (specificity) on the x axis
• test accuracy is measured via the area under the curve

Answer 13

ROC curve

Question 14

probability that a negative test correctly indentifies an individual who does not have that disease

Answer 14

negative predictive value

Question 15

calculation for negative predictive value

Answer 15

true negatives/
true negatives + false negatives

Question 16

most important performance characteristic for a screening test

Answer 16

sensitivity

Question 17

highly sensitive tests produce few…

Answer 17

false negatives

Question 18

ability of test to correctly identify people without disease

Answer 18

specificity

Question 19

calculation for specificity

Answer 19

true negatives/
true negatives + false positives

Question 20

calculation for ARR

Answer 20

mortality in control group - mortality in screened group

deaths/total in control
deaths/total in screened
subtract

Question 21

calculation for NNT

Answer 21

1/ARR

Question 22

occurs when an increased ability to detect disease increases the survival time after diagnosis without changing the course of the disease

Answer 22

lead time bias

Question 23

reason why survival time should not be used as an outcome when evaluating screening tests

Answer 23

lead time bias

Question 24

calculation for relative difference in mortality

Answer 24

mortality in control - mortality in intervention/
mortality in control

Question 25

can mask the actual frequency of the outcome in control in intervention groups

Answer 25

relative difference

Question 26

allows for some understanding of the frequency even if actual numbers aren’t provided

Answer 26

absolute difference