Descriptive Epidemiology Paper

you?continued from previous page)
What does this not tell you?
(white to black) of females with diabetes? What does this tell you?
Out of all white women age 20 and above, what proportion of
them have diabetes? What does this tell you? What does it not tell
and above and how do they compare?
What are the rates of diabetes (per 100) of white and black women
of the 81.1 million white males aged 20 and older, 27.1 million
have high blood pressure. Of the 12.7 million black males,
5.3 million have high blood pressure. What is the ratio of
hypertension among whites versus blacks, the proportion
of hypertension among white males, the rates (per 100) of
hypertension among white and black males, and the relative risk
of hypertension among black versus white males?
10. What is the difference between incidence and prevalence rates?
20
What does each of them reflect or measure? What is the difference
between point prevalence and period prevalence?
11. What are prevalence and incidence rates used for?
12. Assume that Exhibit B.1 summarizes the 2010 population in
the United States by race and gender. Exhibit B.2 presents the
number of US residents in the four race/gender categories with
each of five different risk factors. Use Exhibit B.3 as a template to
calculate the prevalence rate (per 100) of these five risk factors
among the four race/gender categories.
13. What is the difference between cumulative incidence, incidence
rate, and incidence density?
EXHIBIT B.1
US Resident
Population 2010
Prevalence (in thousands)
110,941
White males
112,613
White females
18,596
Black males
20,333
Black females
(table continued on next page)
(continued)
55
Wha
CAPSTONE CASE B: CARDIOVASCULAR DISEASE
7. Out
the
you
By Steven T. Fleming
8. WI
20
o
9.
developed countries. The Framingham study and many others have
Cardiovascular disease is one of the leading causes of death in most
contributed to a rich literature linking a number of risk factors, such
as obesity, high cholesterol, and smoking, to this disease. “Each year,
the American Heart Association (AHA), in conjunction with the Centers
for Disease Control and Prevention, the National Institutes of Health,
and other government agencies, brings together the most up-to-date
statistics on heart disease, stroke, other vascular diseases, and their
risk factors and presents them in its Heart Disease and Stroke Statisti-
cal Update. The Statistical Update is a valuable resource for research-
h h
5
ers, clinicians, healthcare policymakers, media professionals, the lay
10
public, and many others who seek the best national data available on
heart disease, stroke, and other cardiovascular disease-related mor-
bidity and mortality and the risks, quality of care, medical procedures
and operations, and costs associated with the management of these
diseases in a single document” (Go et al. 2013, e7).
QUESTIONS
1. What is descriptive epidemiology?
2. In epidemiology, what does the term population mean?
3. In epidemiology, what are measures of frequency, association, and
impact?
4. What is the difference between a ratio, a proportion, and a rate?
5. Suppose that a 2012 report lists 100 heart attacks, 75 among
men in a population of 25,000 men and 25,000 women. What is
the ratio of heart attacks (men to women), the proportion of the
heart attack report who are men, and the heart attack rate for men
during 2012?
6. Suppose I were to tell you that there are 5.2 million white females
with diabetes in the United States 20 years and older out of a
population of 84.7 million, and 2.2 million black females with
diabetes out of a population of 14.0 million. What is the ratio
(continued)
Capstone Cases
552
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previous page
(continued from previous page)
Prevalence (in thousands)
82,663
EXHIBIT B.1
US Resident
Population 2010
(continued)
White males 19+
White females 19+
86,283
12,697
Black males 19+
Black females 19+
14,291
White males 20+
81,131
White females 20+
84,684
Black males 20+
12,462
Black females 20+
14,026
White males 35+
58,455
White females 35+
61,903
Black males 35+
8,266
Black females 35+
9,294
White males 45+
48,432
White females 45+
51,290
Black males 45+
5,854
Black females 45+
6,561
Prevalence (in thousands)
EXHIBIT B.2
Number of US
Residents in
Thousands)
with Five
ardiovascular
Risk Factors
White
Males
White
Females
Black
Males
Black
Females
Smoking prevalence’
18,847
16,998
2,956
2,118
Obesity (>=30 BMI)2
7,560
27,422
4,723
27,522
Cholesterol >2oomg/d2
32,858
38,785
4,810
5,709
High blood pressure?
27,098
25,998
5,309
6,592
Diabetes mellitus
2,160
6,247
5,250
1,682
1: age 19 and older
2: age 20 and older
Source: Go et al. (2013).
continued)
Prevalence (in thousands)
Prevalence rate (per 100)
KHIBIT B.3
Number of US
Residents (in
Thousands)
with Five
Cardiovascular
Risk Factors
White
Males
White
Females
Black
Males
Black
Females
White
Males
White
Females
Black
Males
Black
Females
Smoking prevalence
18,847
16,998
2,956
2,118
Obesity (>=30 BMI)2
27,422
27,522
4,723
7,560
Cholesterol >2oomg/d?
32,858
38,785
4,810
5,709
27,098
High blood pressure
25,998
6,592
5,309
1,682
5,250
2,160
6,247
Diabetes mellitus?
1: age 19 and older
2: age 20 and older
Source: Go et al. (2013).
(continued)
553
(continued from p
Capstone Cases
554
QUESTIONS
What is
per 100
(continued from previous page)
14.
Suppose you were doing a study on whether coffee drinking
increased the risk of heart disease (see Exhibit B.4). Assume that you
heart disease. You had two group of 110 subjects, each whom you fol.
are no longer at risk of heart disease if you die, leave the study, or get
15. What is
per 100
16. How m
lowed for five years.
drinke
17. How m
n = 110
Coffee Drinkers
coffee
Group 1
18. What
4
5
Risk
EXHIBIT B.4
Coffee Drinking
and Heart
Disease Study
3
2
1
patie
Disease
What
90
Left
19.
5
Died
5
patie
20. Usin
coff
21. Usi
dri
22. Ass
5
5
Non-Coffee Drinkers
n = 110
Group 2
3
4
5
1
N
an
he
th
re
ti
100
2
r
N
2
N
Group 1 (the coffee drinkers): 90 followed for 5 years without get-
ting heart disease, 5 each get heart disease at the end of years 3 and
4, respectively, 5 leave the study at the end of year 2, and 5 die at the
end of year 4.
Group 2 (non-coffee drinkers): 100 followed for 5 years without
getting heart disease, 2 each get heart disease at the end of years 1
and 2, respectively, 3 leave the study at the end of year 4, 3 die at the
2
end of year 3.
frontinued)