Abstract Nut Consumption EXAM 3

Question 1

What is the primary endpoint (hard outcome) of the study?

Answer 1

Mortality

Question 2

What is a Surrogate outcome (Surrogate measure)?

Answer 2

-Measure of effect of a treatment, related to the primary endpoint

-f.e. reduction of LDL -> does it reduce death (primary endpoint) related to LDL?

Question 3

Why are Surrogate

Answer 3

-easier to obtain than the primary outcome
-takes time to determine the primary outcome (death of cardiac events -> f.e. it is more likely in the elderly so it would take time to measure death)

Question 4

What type of study is presented here?

Answer 4

Cohort study - Retrospective

Question 5

Participants with a history of cancer, heart disease, or stroke were excluded.
What type of Validity is affected by the exclusion?

Answer 5

Internal Validity
-reduce confounding variables

Question 6

Why is the unit person*years used in the study?

Answer 6

-Bc the duration of exposure to nuts is different

to have a unique unit for all patients the duration of exposure is multiplied by the #of patients

Question 7

The hazard ratios for death among participants who ate nuts, as compared with those who did not, were 0.93

What is the reduction in risk (RRR)?

Answer 7

7%

1 (= 0 Hypothesis) - 0.93 = 0.07 * 100 = 7%

Question 8

The risk of death of those eating nuts is compared to those who don’t need nuts. If the HR is 0.93, is the exposure to nuts considered beneficial or harmful?

Answer 8

The exposure (here nuts) is in the numerator ->
the HR is less than 1, meaning that the number and the risk for the group in the numerator are smaller

-> BENEFICIAL

Question 9

The 95% confidence interval [CI] is 0.90 to 0.96 for the consumption of nuts less than once per week.
Is it statistically significant?

Answer 9

Yes, it does not include 1

Question 10

Follow-up questionnaires are sent biennially to update medical and lifestyle information

What type of bias is associated with that statement?

Answer 10

Recall Bias

-patients may not be able to remember (recall) the information

Question 11

Table 1 Demographics

Which of the characteristics are potential profounders?

Answer 11

-BMI
-Physical activity: those who eat nuts more often tend to exercise more
-Smoker: those who eat nuts more often tend to smoke less

-unequal number indicate a potential cofounder?

Question 12

In the Forrest Plot:
What does the dotted line stand for?

Answer 12

0 Hypothesis
for HR: 1

Question 13

In the Forrest Plot:
What doe the whiskers stand for?

Answer 13

Confidence interval

Question 14

In the Forrest Plot:
Which of the peanuts considered helpful in cancer is NOT statistically significant?

Answer 14

Peanuts
-it crosses the dotted line, which is the 0 Hypothesis
-so it includes 1 (0 Hypothesis)