A case-control study was performed to assess the relationship between saturated fat intake and heart disease. Among a group of 527 men with heart disease 212 reported diets high in saturated fat and among 1054 controls without heart disease 315 reported high fat intake. Construct the appropriate 2x2 table and calculate and interpret the measure of association (5 points)

A screening program for diabetes mellitus among a workforce of 10,000 employees detects 1,000 employees with diabetes during the initial screening. Forty-five new cases are detected at a subsequent annual screen one year later. (Assume no entry or loss of employees and no deaths during the observation period.) (5 points)

What is the estimated prevalence of diabetes at the outset?

What is the estimated incidence rate of new case development?

What is the estimated annual risk of developing diabetes?

A prospective study of 10152 children in Rwanda was designed to determine the relationship between cooking practices (3-stone fire) and acute respiratory illness (ARI) among children under 5 years old. Specifically, the use of traditional cook stoves (3-stone fire) was compared to the use of improved, low emission cook stoves distributed through a government program. After one year of follow-up, the study produced the following results: (5 points)

	Subgroup		Number		ARI
	Traditional stove		2302		240
	Improved stove		7850		273
	Total		10152		513

Based on the data provided, determine: (a) the cumulative incidence ratio of ARI due to traditional stove use, respectively, (b) the attributable fraction among the exposed (traditional stove use being the exposure) for ARI, and (c) the population attributable fraction for ARI related to stove use. In each case, indicate what your answer means in words. Are traditional stoves associated with greater morbidity from ARI, and what is the benefit of using an improved stove relative to a traditional stove? (5 points)

A large hospital wanted to study the relationship between 10-minute Apgar score (a measure of physiologic stability of neonates at birth on a scale of 0 10) and infant mortality during the first year. Over two years the investigators identified 125 infants with a very low (0-3) Apgar score, of whom 55 died within a year, and 350 with a moderately low (4-6) Apgar score of whom 45 died within a year. Calculate and interpret the preferred estimates of risk of death in each group and the relative risk comparison. (5 points)

In a randomized trial, fifteen out of twelve-hundred 65-year-old men assigned to a high fat diet developed prostate cancer over 10 years compared to 10 out of twelve hundred given a low fat diet. Name, calculate, and interpret your preferred estimate of the relative risk (hint pages 401-402. (5 points)

We have a blood test that we want to use to screen a high-risk population for a serious debilitating disease. (10 points)

The following table indicates the results of applying this test to 225 individuals at risk for this disease. Please calculate and interpret the sensitivity, specificity, and positive & negative predictive values.

	True Disease
Test Result (cut-off 20 mg/liter)		+	-
+	115	10	125
-	11	89	100
	126	99

This table indicates what happens when the cut-off point is changed to 10 mg/liter. Describe how and why this change in cut-off affects the sensitivity, specificity, and predictive values (positive & negative).

	True Disease
(cut-off 10 mg/liter)		+	-
+	124	41	165
-	2	58	60
	126	99

Calculate the expected new predictive values (both positive & negative) when this test is taken into the general population where the prevalence of undiagnosed disease is 5%.