Assignment - Confounding
The following questions relate to the Yang article.
Article - Research on Esophageal Cancer in China: a Review by Chung S. Yang
QUESTION 1 - Into what four categories can the potential contributors to the development of esophageal cancer in Lin Xian be grouped?
a. Nutritional Factors, Environmental Factors, Infectious Factors, and Physiologic Factors.
b. Nutritional Factors, Socioeconomical Factors, Infectious Factors, and Physiologic Factors.
c. Nutritional Factors, Environmental Factors, Political Factors, and Physiologic Factors.
d. Nutritional Factors, Environmental Factors, Socioeconomical Factors, and Physiologic Factors.
QUESTION 2 - What specific nutritional risk factors were presented as suspects in causing esophageal cancer? Select all that apply.
Trace elements in plants
Deficiencies in the diet from low level vitamins
Pickled/fermented vegetables
None of the above
QUESTION 3 - What specific environmental risk factors were presented as suspects in causing esophageal cancer? Select all that apply.
Nitrosamines and their precursors
Moldy food
Trace elements in the soil
None of the above
QUESTION 4 - What specific infectious risk factors were presented as suspects in causing esophageal cancer? Select all that apply.
Mold in fermented food
Dental caries
Trace elements in the food
None of the above
QUESTION 5 - What specific physiologic risk factors were presented as suspects in causing esophageal cancer? Select all that apply.
Sex differences
High food temperature
Genetic predispostion
None of the above
QUESTION 6 - Confounding 6-Crude: The following table represents hypothetical numbers of the "crude" relationship between esophageal cancer and pickled cabbage taken from an unmatched case control study. Calculate the odds ratio and state the meaning of this odds ratio in words.
|
Esophageal Cancer
|
|
|
Pickled Cabbage
|
Cases
|
Controls
|
Totals
|
|
Yes
|
200
|
65
|
265
|
|
No
|
56
|
100
|
156
|
|
Totals
|
256
|
165
|
|
a. OR=2.1 The odds of prior exposure to pickled cabbage among cases are 2 times greater than the same odds among controls.
b. OR=0.4 The odds of prior exposure to pickled cabbage among cases are 60% less than the same odds among controls.
c. OR=5.5 The odds of prior exposure to pickled cabbage among cases are 5½ times greater than the same odds among controls.
d. None of the above
QUESTION 7 - Confounding 7- Smoking & EC::You are asked to evaluate whether smoking, soil nitrate content, and/or lack of vitamins are confounders of the pickled cabbage-esophageal cancer relationship. To evaluate confounding, first consider criterion #1 - whether the "potential confounder" is a risk factor for esophageal cancer. Which of these three potential confounders fit the criterion of being a risk factor for the disease? [Hint: Calculate the appropriate measure of association between smoking and esophageal cancer.] .
|
Esophageal Cancer
|
|
|
Smoking
|
Cases
|
Controls
|
Totals
|
|
Yes
|
120
|
80
|
200
|
|
No
|
136
|
85
|
221
|
|
Total
|
256
|
165
|
|
a. OR=0.94. There is no clear relationship between smoking and being a case
b. RR=0.94. There is no clear relationship between smoking and being a case
c. RR=0.76. There appears to be a relationship between smoking and being a case
d. None of the above
QUESTION 8 - Confounding 8-Nitates & EC::You are asked to evaluate whether smoking, soil nitrate content, and/or lack of vitamins are confounders of the pickled cabbage-esophageal cancer relationship. To evaluate confounding, first consider criterion #1 - whether the "potential confounder" is a risk factor for esophageal cancer. Which of these three potential confounders fit the criterion of being a risk factor for the disease? [Hint: Calculate the appropriate measure of association between nitrates in the soil and esophageal cancer.] .
|
Esophageal Cancer
|
|
|
Nitrates in the soil
|
Cases
|
Controls
|
Totals
|
|
High
|
150
|
44
|
194
|
|
Low
|
106
|
121
|
227
|
|
Total
|
256
|
165
|
|
a. OR=0.26 There appears to be a relationship between high soil nitrates and being a case.
b. OR=3.89. There appears to be a relationship between high soil nitrates and being a case.
c. RR=1.25. There appears to be a relationship between high soil nitrates and being a case.
d. None of the above
QUESTION 9 - Confounding 9-Vitamins & EC::You are asked to evaluate whether smoking, soil nitrate content, and/or lack of vitamins are confounders of the pickled cabbage-esophageal cancer relationship. To evaluate confounding, first consider criterion #1 - whether the "potential confounder" is a risk factor for esophageal cancer. Which of these three potential confounders fit the criterion of being a risk factor for the disease? [Hint: Calculate the appropriate measure of association between vitamins and esophageal cancer.]
|
Esophageal Cancer
|
|
|
Vitamins
|
Cases
|
Controls
|
Totals
|
|
Deficient
|
129
|
65
|
194
|
|
Normal
|
127
|
100
|
227
|
|
Totals
|
256
|
165
|
|
a. OR=0.64. There appears to be a relationship between vitamin intake and being a case.
b. OR=1.56. There appears to be a relationship between vitamin intake and being a case.
c. OR=0.75. There appears to be a relationship between vitamin intake and being a case.
d. None of the above
QUESTION 10 - Confounding 10-Smoking &PC: Next evaluate whether the three potential confounders fulfill criterion #2 for confounding - the confounder is associated with the exposure but is not a result of the exposure. Assume that none of these three potential confounders resulted from exposure to pickled cabbage. Which of these three potential confounders fit the criterion of being related to the exposure? Calculate the appropriate measure of association between smoking and pickled cabbage
|
Pickled Cabbage
|
|
|
Smoking
|
Yes
|
No
|
Totals
|
|
Yes
|
160
|
40
|
200
|
|
No
|
105
|
116
|
221
|
|
Totals
|
265
|
156
|
|
a. OR=1.27. There is an association between the potential confounder (smoking) and the exposure (pickled cabbage).
b. OR=4.42. There is an association between the potential confounder (smoking) and the exposure (pickled cabbage).
c. OR=0.23. There is no association between the potential confounder (smoking) and the exposure (pickled cabbage).
d. None of the above
QUESTION 11 - Confounding 11-Nitrates &PC: Next evaluate whether the three potential confounders fulfill criterion #2 for confounding - the confounder is associated with the exposure but is not a result of the exposure. Assume that none of these three potential confounders resulted from exposure to pickled cabbage. Which of these three potential confounders fit the criterion of being related to the exposure? Calculate the appropriate measure of association between nitrates in the soil and pickled cabbage
|
Pickled Cabbage
|
|
|
Nitrates in soil
|
Yes
|
No
|
Totals
|
|
High
|
100
|
94
|
194
|
|
Low
|
165
|
62
|
227
|
|
Total
|
265
|
156
|
|
a. RR=0.53. There is an association between the potential confounder (high nitrates in soil) and the exposure (pickled cabbage).
b. OR=2.64. There is an association between the potential confounder (high nitrates in soil) and the exposure (pickled cabbage).
c. OR=0.40 There is an association between the potential confounder (high nitrates in soil) and the exposure (pickled cabbage).
d. None of the above
QUESTION 12 - Confounding 12-Vitamins &PC:: Next evaluate whether the three potential confounders fulfill criterion #2 for confounding - the confounder is associated with the exposure but is not a result of the exposure. Assume that none of these three potential confounders resulted from exposure to pickled cabbage. Which of these three potential confounders fit the criterion of being related to the exposure? Calculate the appropriate measure of association between vitamins and pickled cabbage
|
Pickled Cabbage
|
|
|
Vitamins
|
Yes
|
No
|
Totals
|
|
Deficient
|
123
|
71
|
194
|
|
Norma
|
142
|
85
|
227
|
|
Totals
|
265
|
156
|
|
a. OR=0.96. There is no clear association between the potential confounder (low vitamin intake) and the exposure (pickled cabbage).
b. OR=0.85. There is an association between the potential confounder (low vitamin intake) and the exposure (pickled cabbage).
c. OR=1.04. There is no clear association between the potential confounder (low vitamin intake) and the exposure (pickled cabbage).
d. None of the above
QUESTION 13 -
1. Confounding 13-Stratified: Using the data from the tables in questions 7-12 to to complete the marginals and the table cells with information provided below to complete the cells. Complete the stratified analysis as outlined in the blank tables below. After completing the tables, calculate the odds ratio for each 2x2 table and determine from your results whether any of the three factors are confounders
|
Data for Table cells
|
|
Factor
|
Cell a
|
Cell b
|
Cell c
|
Cell d
|
|
Smoking Yes
|
109
|
51
|
11
|
29
|
|
Smoking No
|
85
|
20
|
51
|
65
|
|
Nitrates High
|
84
|
16
|
66
|
28
|
|
Nitrates Low
|
86
|
79
|
20
|
42
|
|
Vitamin Normal
|
101
|
41
|
26
|
59
|
|
Vitamin Deficiency
|
99
|
24
|
30
|
41
|
a. Smoking Yes OR=5.63; Smoking No OR=5.42
b. Nitrates High OR=2.23; Nitrates Low OR=2.29
c. Vitamin Normal OR=5.59; Vitamin Deficient OR=5.64
d. None of the above
Attachment:- Assignment Files.rar