4. Women's Health Initiative conducted a prospective cohort study to determine if high intake of dietary fat

was a risk factor for developing cardiovascular disease (CVD) among women. The investigators recruited

1150 women (45-89 years old) who were free of CVD at the baseline of the study in 2005. Each participant

completed a standardized dietary questionnaire to quantify dietary fat intake. The participants were

divided into a "low-intake of dietary fat" group (830 women in this group) and the "high intake of dietary

fat" group (320 women in this group) based on the information that they provided in their dietary

questionnaire. Participants were then followed for a total of 10 years to detect if any of them developed

CVD while being in this study. At the end of the follow-up period, the number of women in each group

who developed CVD and the person-years contributed by each group were recorded.

a. What is the prevalence of low intake of dietary fat vs. high intake of dietary fat in this population?

b. Calculate and interpret the cumulative incidence per 1000 population for CVD for the entire cohort,

for women consuming low intake of dietary fat, and for women consuming high intake of dietary fat.

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C.

Calculate and interpret the incidence rate per 1000 person-year for CVD for the entire cohort, for

women consuming low intake of dietary fat, and for women consuming high intake of dietary fat.

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d. Compare the estimates of incidence rate calculated by you in 4c. Explain what may account for the

observed difference in the measures of the incidence rate among the low-intake of dietary fat group

and high-intake of dietary fat group.