10. Clin Epi Freq of Disease/Risk

Question 1

A study is examining the prevalence of smoking and lung cancer in a population of 500 people. 150 people were smokers and developed lung cancer. 50 people developed lung cancer who did not smoke. 75 people smoked and did not get lung cancer. 225 people did not smoke and did not develop lung cancer. Calculate the strength of association between smoking and lung cancer.

A. 3.7
B. 0.27
C. 1
D. 9.1
E. 2.4

SZ

Answer 1

Ans A 3.7
Strength of association is the Relative Risk which is equal to incidence of exposed/incidence unexposed. TP = 150, FP=75, FN=50, TP=225. To calculate (TP/(TP+FP))/(FN/(FN+TN)). (150/(150+75))/(50/(50+225))=3.7

Question 2

A study is examining the prevalence of smoking and lung cancer in a population of 500 people. 150 people were smokers and developed lung cancer. 50 people developed lung cancer who did not smoke. 75 people smoked and did not get lung cancer. 225 people did not smoke and did not develop lung cancer. Calculate the incidence of developing lung cancer if smoking is eliminated?

A. 3.7
B. 0.27
C. 0.49
D. 2.4
E. 0.37

SZ

Answer 2

Ans C 0.49
Attributed risk answers the question; How much of the risk of disease can we hope to prevent if we are able to eliminate exposure to the agent in question? If TP = 150, FP=75, FN=50, TP=225. AA = (TP/(TP+FP))-(FN/(FN+TN)). (150/150+75))-(50/50+225))=0.49

Question 3

Ahmed works at a nuclear power plant and has recently noticed that his has grown a fully functional 3rd nipple on his forehead. After a few weeks of enjoying this new appendage he begins to become self conscious and starts wearing a bra around his forehead like a bandana. This solution proves to be fruitless and now is pursuing legal action against the power plant for damages. The power plant argues there is no know link to exposure to radiation to growth of a third nipple on foreheads. So in response Ahmed creates a research study to help his cases in his research he found 669 people exposed to radiation grew a 3rd nipple on their forehead, 420 have a nipple on their forehead and were not exposed to radiation, 101 people were exposed to radiation and don’t have a 3rd nipple on their forehead and 1234 were not exposed to radiation and don’t’ have a 3rd nipples on their forehead. What is the association between exposure and outcome in this scenario?

A. 0.1
B.19.5
C.7.7
D.15.1
E 23.4

RFA

Answer 3

Ans. B this measure is call odds ration and is (expose with x no expose w/o) /( no expose with x exposed w/o)

(6691234)/(420101)=19.5

Question 4

So now Ahmed need to find the measure of strength of of exposure to the radiation Again 669 people exposed to radiation grew a 3rd nipple on their forehead, 420 have a nipple on their forehead and were not exposed to radiation, 101 people were exposed to radiation and don’t have a 3rd nipple on their forehead and 1234 were not exposed to radiation and don’t’ have a 3rd nipples on their forehead.

A.3.42
B.8.12
C.2.39
D.1.81
E.5.09

RFA

Answer 4

B. 8.12

Relative risk is the measure of strength of aassociation is is a major factor in considering causal inferences.

RR=(669/669+420)/(101/101+1234)

Question 5

If the Relative Risk is less than 1 which of the following statements is most true?

A) No association btwn exposure and risk
B) Possibly Causal
C) Possibly protective
D) Association btwn exposure and risk

MM

Answer 5

Ans C aka negative association and most likely not associated

Question 6

50 out of 100 SGU males who were exposed to the asbestos in Taylor study hall developed extremely large Male vaginas. 5 out of 100 SGU males who only study in Monica developed male vaginas. What is the odds ratio that study in Taylor makes you grow a vagina?

A) 1
B) 10
C) 100
D) 1000
E) 10000

MM

Answer 6

Ans = B

Question 7

You are conducting a study to see if exposure to sea water causes folliculitis. You find that people are more likely to conduct folliculitis if they have been swimming at Groom’s Beach. What is the relative risk? (MG)

A. 1
B. >1
C. <1
D. 0

Answer 7

B. >1

Positive association, possibly causal

Question 8

You are conducting a study to see if exposure to sea water causes folliculitis. Of people who have been swimming at Groom’s Beach this past month, 90/100 have contracted folliculitis. Out of 100 students who have not been to the beach in the past month, 2 have contracted folliculitis. What is the attributable risk? (MG)

A. 0.9-0.02
B. (0.9-0.02)/0.46
C. 0.02-0.9
D. (0.02-0.9)/0.02

Answer 8

A. 0.9-0.02

B is the attributable risk FRACTION