Deck 9: Measures of Effect

Question 1

The term attributable risk is defined as the ratio of the incidence of a disease among exposed individuals to the incidence among nonexposed individuals.

Answer 1

False

Question 2

The term attributable risk is also known as the rate difference or risk difference.

Answer 2

True

Question 3

The population etiologic fraction is a measure of the proportion of the disease rate in a population attributable to the exposure of interest. This measure of effect is influenced by:

A) the relative risk of the disease in exposed individuals versus unexposed individuals.
B) the prevalence of the disease in the population.
C) the prevalence of the exposure in the population.
D) the relative risk of the disease in exposed individuals versus unexposed individuals and the prevalence of the disease in the population.
E) the relative risk of the disease in exposed individuals versus unexposed individuals and the prevalence of the exposure in the population.

Answer 3

E

Question 4

The population etiologic fraction for a particular disease from Factor X alone is five times greater than that from Factor Y alone. If the relative risk associated with Factor X is 2, and with Factor Y is 20, which of the following statements is true?

A) The risk of developing the disease is greater in those exposed to Factor X only than in those exposed to Factor Y only.
B) Fewer persons are exposed to Factor Y than to Factor X.
C) The proportion of the disease in the population attributable to Factor Y is greater than that attributable to Factor X.
D) More persons are exposed to Factor Y than to Factor X.
E) The risk of developing the disease for persons exposed to Factor Y is five times greater than for persons exposed to Factor X.

Question 5

The death rate per 100,000 for lung cancer is 7 among nonsmokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among nonsmokers and 599 among smokers. The prevalence of smoking in the population is 55%. The relative risk of dying for a smoker compared to a nonsmoker is:

A) 9.1 for lung cancer and 0.30 for coronary thrombosis.
B) 9.1 for lung cancer and 1.4 for coronary thrombosis.
C) 10.1 for lung cancer and 8.4 for coronary thrombosis.
D) 10.1 for lung cancer and 1.4 for coronary thrombosis.
E) 12.4 for lung cancer and 1.7 for coronary thrombosis.

Question 6

The death rate per 100,000 for lung cancer is 7 among nonsmokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among nonsmokers and 599 among smokers. The prevalence of smoking in the population is 55%. Among smokers, the etiologic fraction of disease due to smoking is:

A) 0.90 for lung cancer and 0.88 for coronary thrombosis.
B) 0.90 for lung cancer and 0.29 for coronary thrombosis.
C) 0.89 for lung cancer and 0.88 for coronary thrombosis.
D) 0.89 for lung cancer and 0.29 for coronary thrombosis.
E) It cannot be determined from the information provided.

Question 7

The death rate per 100,000 for lung cancer is 7 among nonsmokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among nonsmokers and 599 among smokers. The prevalence of smoking in the population is 55%. The population etiologic fraction of disease due to smoking is:

A) 0.80 for lung cancer and 0.28 for coronary thrombosis.
B) 0.80 for lung cancer and 0.18 for coronary thrombosis.
C) 0.83 for lung cancer and 0.28 for coronary thrombosis.
D) 0.83 for lung cancer and 0.18 for coronary thrombosis.
E) It cannot be determined from the information provided.

Question 8

The death rate per 100,000 for lung cancer is 7 among nonsmokers and 71 among smokers. The death rate per 100,000 for coronary thrombosis is 422 among nonsmokers and 599 among smokers. The prevalence of smoking in the population is 55%. On the basis of the relative risk and etiologic fractions associated with smoking for lung cancer and coronary thrombosis, which of the following statements is most likely to be correct?

A) Smoking seems much more likely to be causally related to coronary thrombosis than to lung cancer.
B) Smoking seems much more likely to be causally related to lung cancer than to coronary thrombosis.
C) Smoking seems to be equally causally related to lung cancer and coronary thrombosis.
D) Smoking does not seem to be causally related to either lung cancer or coronary thrombosis.
E) No comparative statement is possible between smoking and lung cancer or coronary thrombosis.

Question 9

If it is accepted that an observed association is a causal one, an estimate of the impact that a successful preventive program might have can be derived from:

A) relative risk.
B) higher life expectancy.
C) attributable risk.
D) prevalence rates.
E) All are correct.

Question 10

Assuming that the following sample table is for a cohort study, define the risk difference or attributable risk:

A) (A/A + C) / (B/B + D)
B) (A/A + B) / (C/C + D)
C) (A/A + C) − (B/B + D)
D) (A/A + B) − (C/C + D)
E) None of these is correct.

Question 11

When assessing a positive relationship between alcohol consumption and oral cancer using a case-control study, increasing the sample size of the study will result in which of the following?

A) A lower p value and a smaller 95% confidence interval
B) A greater odds ratio and a higher disease prevalence
C) A lower p value, a smaller 95% confidence interval, and a greater odds ratio
D) A lower p value, a smaller 95% confidence interval, a higher disease prevalence, and a greater odds ratio
E) None of these is correct.

Question 12

A causal association between factor and outcome can refer to:

A) statistical independence.
B) secondary association.
C) indirect association.
D) direct association.
E) indirect association and direct association.

Question 13

Calculate the proper measure of association of smoking and lung cancer death. Interpret your results. [Relative risk (RR) = 3.2]

Question 14

Calculate the population risk difference. Interpret your results. [I_P = 48.6 per 100,000; I_ne = 19.1 per 100,000; I_P − I_ne = 48.6 − 19.1 = 29.5/100,000 per year]

Question 15

Calculate the population etiologic fraction for smoking and lung cancer based on these data. Interpret your results. [29.5/48.6 × 100 = 60.7%]