Transcript DESCRIPTIVE EPIDEMIOLOGY for Public Health Professionals Part 4 Ian R.H. Rockett, PhD, MPH Department of Community Medicine West Virginia University School of Medicine Prepared under the.

DESCRIPTIVE EPIDEMIOLOGY
for Public Health Professionals
Part 4
Ian R.H. Rockett, PhD, MPH
Department of Community Medicine
West Virginia University School of Medicine
Prepared under the auspices of the
Southeast Public Health Training
Center, University of North Carolina,
Chapel Hill, 2005.
[email protected]
From
MEASUREMENT
to
DESCRIPTION
Descriptive Epidemiology
Magnitude of the Problem
- how big?
Person, Place, and Time
- who, where, and when?
Magnitude of the
Problem
Injury Deaths Worldwide by Leading Causes
and Intent, 1990
Person
Place
and
Time
PERSON
 Demographic characteristics e.g. age,
sex, race, marital status, number of
children
 Socioeconomic characteristics
e.g. social class, employment
status, occupation
Life style/behavior e.g. drinking
alcohol/smoking marijuana and
driving
FigureStates
1. United Suicide
States Suicide
Rates by
Age,
Sex, and
Racial
Group,
United
Rates
by
Age,
Sex,
and
Racial
Group,1999-2001
1999-2001
70
White Male
Black Male
White Female
Black Female
60
Rate per 100,000
50
40
30
20
10
0
15-19 20-24 25-34
35-44
45-54
55-64
65-74
75-84
85+
Age (in years)
Data accessed through CDC Wonder: http://wonder.cdc.gov/mortICD10J.html
PLACE
Are the disease or injury cases:
geographically confined or
pervasive?
clustering around known potential
pathogens, toxins, or other
hazards?
TIME
Are disease (injury) rates or case
numbers variable or constant?
Do rates or case numbers vary seasonally?
Is the disease attributable to a point
source of infection or propagated
transmission?
Source: McAuley, J. et al. A Trichinosis Outbreak Among Southeast
Asian Refugees (1992). American Journal of Epidemiology 135(12):14041410. Reproduced in Rockett, I.R.H. Population and Health: An
introduction toEpidemiology(1999). Population Bulletin 54(4):23.
Descriptive Study
Designs
Correlational (Ecological) Study –
uses data from entire populations to
compare disease/injury frequencies
in relation to putatively harmful
(or beneficial) exposures during the
same period of time or at different
points in time (typically use secondary
published data like vital statistics,
censuses and national health surveys)
Source: Len Evans. Traffic Crashes. American Scientist 90 (3); 2002:
246. http://www.dushkin.com/text-data/articles/34749/body.pdf
Case Report - most basic type of
descriptive study of individuals,
comprising a careful detailed report
by one or more clinicians that
profiles a single patient’s case
Case Series – describe
characteristics of a number of
patients with a given disease
Cross-Sectional Studies –
the status of an individual with
respect to the presence or
absence of both exposure and
disease/injury of interest is
assessed at one point in time (if
the timing of each cannot be
differentiated, this too qualifies a
study as cross-sectional)
HYPOTHESIS
FORMULATION
The Bridge to
Analytic Epidemiology
Method of Difference
Examines differences among
groups for clues as to why
the groups’ disease rates or
other health problems vary
Source: Ian R.H. Rockett. Population and Health: An Introduction to Epidemiology.
Second edition. Population Bulletin 54(4); 1999: 17.
Method of Agreement
Looks for
commonality in
groups that manifest
the same health
problem
Method of
Concomitant
Variation
Traces how exposure to
a hazard varies in
relation to disease or
other health problems
Problem of Chronic
Disease Latency
Source: Doll, R.
Etiology of Lung
Cancer (1955).
Advances in
Cancer Research
3;1955:1-50.
Reproduced in
I.R.H. Rockett.
Population and
Health: An
introduction to
Epidemiology,
Second edition.
Population
Bulletin,54(4);1999:
25.
Early Intervention in the Natural
History of Disease
Good
Health
Disease
Onset
Symptoms
Care Diagnosis Therapy
Seeking
Early detection through
Screening
HEALTH
OUTCOMES
Cure
Control
Disability
Death
Method of Analogy
Involves applying a model that
characterizes one kind of
disease or injury to another
kind
Method of Detection of
Conflicting Observations
Pellagra, commonly
regarded as a
communicable disease,
produced skin eruptions
and digestive and nervous
disorders
Joseph Goldberger,
1874-1929
•
Laboratory Observations
Even though lacking
research experience, Dr.
Barry Marshall and Dr.
Robin Warren were able to
link peptic ulcers to the
bacterium Helicobacter
Pylori
Source: University of Western Australia. UniView 22(1);2003:4.
ANALYTIC
EPIDEMIOLOGY
Addressing the why question
From
Epidemiology to
Population Health
Health
Life Expectancy:
Life Years
vs.United
Years
Years
of Healthy
Life vs. Years
of Life,
of Healthy Life
in the
United Sates, 1990
States,
1990
3000
YL
YHL
Years
2500
2000
1500
1000
500
0
0-10
10 to 20
20-30
30-40
40-50
Age (in years)
50-60
60-70
70-80
80+
To Access Some Online
Epidemiology Texts
Visit
http://www.epidemiolog.net/evolving/
TableOfContents.htm
http://www.prb.org/Template.cfm?Section=Pop
ulation_Bulletin1&template=/ContentManagem
ent/ContentDisplay.cfm&ContentID=9854
http://bmj.com/epidem/epid.html