Transcript No Slide Title

The Role of Epidemiology in
Public Health Practice
James Buehler, MD
Rollins School of Public Health
Emory University
Atlanta, Georgia
Pennsylvania
Public Health Institute
May 28, 2004
June 4, 2004, 5:02 PM ET
WHAT IF ?
BIRD FLU SPREADS IN ASIA
By FLORENCE ARTMAN
Published: June 4 2004
Influenza vaccine available. A
new influenza vaccine promises
protection against “bird” flu.
Image source: cnn.com
GENEVA, Switzerland, June 4 — The World Health Organization (WHO)
confirmed today that an new outbreak of a “bird flu” has sickened over 1,000
people in southeast Asia. The new strain represents the combination of bird
and human strains of influenza and is capable of spreading rapidly among
people. WHO spokesman Dr. David Strawman noted that this represents “a
major setback in international efforts to prevent avian influenza from jumping
to and spreading among humans.”
In Washington, DC, Secretary of Health and Human Services Tommy
Thompson said that senior health officials are considering whether to
recommend widespread use of a new influenza vaccine in the United States.
You are:
Tommy G. Thompson
Secretary of Health and Human Services
Image source: www.hhs.gov
What questions do you have for your staff and
invited experts?
You may be
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Someone who uses epidemiologic
information
Someone who is asked by
epidemiologists to provide information
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Epidemic investigation
Ongoing public health monitoring
An epidemiologist
Overview
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Data are not value-free
Surveillance--the epidemiology balancing act
Epidemics—the investigation toolbox
Science, evidence, epidemiology, & policy
Goals:
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More informed user of epidemiology
More effective partner with epidemiologists
Not everything that counts
can be counted, and not
everything that can be
counted counts.
Albert Einstein
Epidemiologists seek what counts
by counting what can be counted.
Reported AIDS Cases per 100,000
United States, 2001
Race/Ethnicity
Rate
White, non-Hispanic
6.6
Black, non-Hispanic
59.6
Hispanic
20.7
Asian/Pacific Islander
3.8
Am. Indian/Alaska Native
9.0
Source: CDC 2002, http://www.cdc.gov/hiv/stats/
Describing Health Disparities
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Benefits
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Identify questions for research studies
Identify unmet needs for services
Help define priorities for resource use
Assist community advocates
Risks
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Contributes to stigma, marginalization
Oversimplifies population diversity
Fosters misperception problems are not
shared
Rate of Disease X, 2000-2003
Cases per 100,000 Population
60
50
40
Group 1
30
Group 2
20
10
0
2000
2003
Year
True Statements About
Disease X in Groups 1 & 2

Rate of Disease X, 2000-2003
Cases per 100,000 Population
60
50

40
Group 1
30
Group 2
20
10
0
2000
2003
Year

The difference in rates
remained unchanged
The gap decreased from a
50% difference in 2000 to
a 25% difference in 2003
The rate increased 67% in
Group 1 and 100% in
Group 2
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What part of the information story is
most important to tell or emphasize?
What part of the information story best
identifies the need or urgency for
prevention or care?
Depends on values & judgement
To make sense of the numerator, you
need to know something about the
denominator
“The terrorist barriers seem to be working.”
Source: The New Yorker, November 17, 2003
Public Health Surveillance
People who manage programs to prevent or
control disease need reliable, ongoing
information about the status of that disease
(or injury, disability, exposure, risk) in the
population they serve.
The process that epidemiologists use to
collect, manage, analyze, interpret, and
disseminate that information is called
“surveillance.”
The Doctor & the Epidemiologist
Patient
Doctor
Epidemiologist
Person
Population
Monitor health Periodic exam
Surveillance
When the
patient gets
sick
Follow-up
Diagnose &
treat
Research
Clinical study
or trial
Investigate &
recommend
interventions
Program
evaluation
Epi study
Return visit
Desirable Attributes of Surveillance*
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Simple
Flexible
Quality data
Acceptable
Complete
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Cases really cases
Representative
Timely
Stable
Source: CDC. Updated Guidelines for Evaluating Public Health
Surveillance Systems. MMWR R&R, Vol. 50, y July 27, 2001.
* But you can’t have it all—take your pick
2 Case Definitions for Hepatitis A

Acute onset of illness with:*
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*
Jaundice or laboratory evidence of liver
dysfunction (elevated serum aminotransferase
levels) AND
Discrete onset of symptoms AND
Acute-phase antibodies (IgM) to hepatitis A
Yellow eyes
CDC. Case Definitions for Infectious Conditions
Under Public Health Surveillance. MMWR 1997;
46(RR10);18
Change in trend monitored
through surveillance :
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Change
Change
Change
Change
Change
Change
in
in
in
in
in
in
surveillance procedure
surveillance resources
health care practice
screening program
interest in condition
incidence
New York Times, Jan 26, 2004
How will the next BT attack be
detected?
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Overt attack
Environmental sampling
Health care provider notices something
unusual (increase in illness, cluster of cases,
severe clinical pattern) & CALLS HD
Incidental--Routine evaluation & testing
Surveillance detects unusual trend
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Tradition case reporting
“Syndromic surveillance”
Timeline of Bioterrorism Disease
Attack
Severe
disease
Early disease
(less severe)
Can epidemic be
detected sooner?
Admit
to
Hospital
Diagnosis
Challenges:
• Balance timelines & sensitivity
with false alarms
• Identifying illness of public health
importance
Report to
Health Dept.
Possible Data Sources
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Stay home - Absentee records
Buy facial tissue – Grocery store purchases
Buy over-the-counter medicine – Pharmacy records
Call doctor or nurse – Call logs
Primary care visit – Insurance claims, Electronic Medical
Record
Emergency Room – ER logs, triage or discharge data
Antibiotic prescription – Pharmacy records, claims
Lab test done – Laboratory requisitions
Call 911, Emergency Medical Service - EMS logs
Admit to hospital - Hospital admission records
Admit to ICU – ICU logs
Death – Electronic death certificate, Medical examiner
New York City Department of Health and
Mental Hygiene, 2002, Health Alert #37
Source: NYCDoHMH
http://www.nyc.gov/html/doh/html/cd/02md37.html
Epidemic Investigations
Hepatitis A
Image source: http://phil.cdc.gov/
Pennsylvania Hepatitis Outbreak, 2003
The first five patients who showed up…with signs of hepatitis
A infection piqued Dr. Marcus Eubanks' curiosity. But it was
only when the sixth patient arrived on Friday that someone -the patient's wife -- uttered the magic word: [Restaurant A].
The woman told Eubanks, an emergency physician… that
three of the couple's friends had come down with the disease
that week and that the friends had shared a meal in October
at the restaurant…
"He said to me, 'Oh, my God, we've got to call the Health
Department,' " recalled the woman…,"We realized, 'Holy Cow,
this is an outbreak.' "
Source: Pittsburgh Post-Gazette
10 Steps of a Epi Field Investigation
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Determine the existence of the epidemic
Confirm the diagnosis
Define a case and count cases
Determine who is at risk of becoming ill
Develop and test a hypothesis that explains the
exposure that caused disease
Compare the hypothesis with established facts
Plan a more systematic study
Prepare a written report
Execute control & prevention measures
Gregg MB. Field Epidemiology, 2nd ed. Oxford Univ Press 2002
PENNSYLVANIA DEPARTMENT OF HEALTH
HEALTH ALERT #61
To: Health Alert Network
From: Calvin B. Johnson, M.D., M.P.H. Secretary of Health
Date: November 3, 2003
Subject: Large Outbreak of Restaurant-Associated
Hepatitis A
Source: http://www.dsf.health.state.pa.us
10 Steps of a Epi Field Investigation
Determine the existence of the epidemic
 Confirm the diagnosis
 Define a case and count cases
 Determine who is at risk of becoming ill
An
alert clinician contacted PADOH…to report an
 Develop and
test a Ahypothesis
explains
IgM-positive
hepatitis
case, and that
noted
that asthe
exposure
that caused
disease
many
as 10 other
cases of
hepatitis had been seen
 Compare
with
established facts
recently
in a the
localhypothesis
Emergency
Department.
 Plan a more systematic study
Source:
PA DoHa written report
 Prepare
 Execute control & prevention measures

10 Steps of a Epi Field Investigation
Determine the existence of the epidemic
 Confirm the diagnosis
 Define a case and count cases
 Determine who is at risk of becoming ill
 Develop
test a hypothesis
that explains
Over
the nextand
36 hours,
additional probable
casesthe
were
exposure
that
disease
identified
based
on caused
symptoms,
and 7 other IgM-positive
 Compare
the hypothesis with established facts
cases
were reported.
 Plan a more systematic study
Source:
PA DoH a written report
 Prepare
 Execute control & prevention measures

10 Steps of a Epi Field Investigation
Determine the existence of the epidemic
 Confirm the diagnosis
 Define a case and count cases
 Determine who is at risk of becoming ill
 Develop and test a hypothesis that explains the
exposure that caused disease
All but one community case of hepatitis A interviewed
 Compare the hypothesis with established facts
so far had a single common risk factor, eating at
 Plan a more systematic study
[Restaurant
A] in early October.
 Prepare a written report
 Execute
Source:
PA DoH control & prevention measures

Source: CDC MMWR
10 Steps of a Epi Field Investigation
Determine the existence of the epidemic
 Confirm the diagnosis
 Define a case and count cases
 Determine who is at risk of becoming ill
 Develop and test a hypothesis that explains the
exposure that caused disease
 Compare the hypothesis with established facts
 Plan a more systematic study
No single
food item has been implicated, and one
 Prepare
a written
report
hypothesis
is that
an ill food
worker inadvertently
 Executemultiple
control food
& prevention
measures
contaminated
items during
preparation or
serving.

Source: PA DoH
The Department of Agriculture sent an inspector to the
restaurant…; the inspector found no sanitary violations and
10 Steps
a EpiThe
Field
Investigation
emphasized
strict of
hygiene…
restaurant
corporate office
has voluntarily closed the facility.
 Determine the existence of the epidemic
A state
health center clinic is being arranged to administer
 Confirm
diagnosis
immune
serumthe
globulin
(ISG) to well restaurant workers. A
 Define
case and
countthe
cases
press
releasea which
includes
address of the clinic will be
 Determine
released
shortly. who is at risk of becoming ill
 Develop and test a hypothesis that explains the
Source:exposure
CDC MMWRthat caused disease
 Compare the hypothesis with established facts
 Plan a more systematic study
 Prepare a written report
 Execute control & prevention measures
10 Steps of a Epi Field Investigation









Determine the existence of the epidemic
Confirm the diagnosis
Define a case and count cases
Determine who is at risk of becoming ill
Develop and test a hypothesis that explains the
exposure that caused disease
Compare the hypothesis with established facts
Plan a more systematic study
Prepare a written report
Execute control & prevention measures
Epidemiologists Make
Comparisons

People who are sick versus people who
are not sick
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
How are they different--exposures,
behaviors, etc?
People who have an exposure versus
those who don’t

How are they different—who gets sick?
Epidemiologists Make
Comparisons

People who are sick versus people who
are not sick
 How are
different--exposures,
A case-patient
was they
defined
as a person who had illness
onset during
October etc?
14--November 12, had laboratory
behaviors,
confirmation of acute hepatitis A virus (HAV) infection
PeopleIgM
who
have reported
an exposure
versus
(i.e., positive
anti-HAV),
eating food
those
who don’t
prepared
at Restaurant
A during October 3--6, and had
eaten only
once at Restaurant A during the 2--6 weeks
 How are they different—who gets sick?
before illness onset.
Source: CDC MMWR
Epidemiologists Make
Comparisons

People who are sick versus people who
are not sick
How are
they different--exposures,
Controls included
persons
without hepatitis A who
either hadbehaviors,
dined with case-patients
at Restaurant A or
etc?
were identified through credit card receipts as having
 People who have an exposure versus
dined
at Restaurant A during October 3--6. Controls
don’t
with a those
previouswho
history
of hepatitis A, hepatitis A
vaccination,
or receipt of immune globulin within 2
 How are they different—who gets sick?
weeks after eating Restaurant A food were excluded.
Source: CDC MMWR
Epidemiologists Make
Comparisons

People who are sick versus people who
are not sick

How are they different--exposures,
behaviors, etc?
People who have an exposure versus
Eating
a menu
containing green onions was
those
whoitem
don’t

reported by 98% of case-patients, compared with
 How are they different—who gets sick?
69%
of controls (OR = 20.2, 95%CI = 6.8--59.9).
Source: CDC MMWR
The Food and Drug Administration (FDA), CDC, and the
state
departments
investigating
the source of
10 health
Steps
of a EpiareField
Investigation
the green onions…and how they became contaminated… .
Preliminary traceback information indicates that green
 Determine the existence of the epidemic
onions…were grown in Mexico.
 Confirm the diagnosis
 Define a case and count cases
FDA
issued an alert to consumers about the recent
 Determine who is at risk of becoming ill
hepatitis
A outbreaks associated with green onions. FDA
 Develop
and test
a hypothesis
theof
advised
consumers
concerned
aboutthat
theexplains
possibility
exposure
that
caused
disease
getting
hepatitis
A from
green
onions to cook green onions
 Compare
the hypothesis
established
thoroughly
before
eating and with
to ask
about use facts
of green
 Plan
a more systematic
onions
in prepared
foods. study
Source:
CDC MMWR
 Prepare a written report
 Execute control & prevention measures
Jesus Flores, proprietor of Los Baby's Fruit and Vegetable Stand in
Mexicali, wants to know why Mexican farm workers are not affected by
hepatitis A virus if the produce they handled allegedly is the source of
infection in the United States.
Source: http://www.post-gazette.com/pg/03328/243293.stm
Role of epidemiology in this outbreak
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Identify restaurant as site of exposure
Identify green onions as likely food source
Food not contaminated by restaurant process
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Sanitation experts: Restaurant inspection
Epi: Similar pattern in other states & restaurants
Trigger further environmental investigation:
food “trace-back”
? Close restaurant (policy)
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Based on guidelines set in advance
Based on evidence in this situation
What is the role of epidemiology
in public health practice?

Need to step back: What is the role
evidence?
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Information collected and assessed using
tools of science
Epidemiology—a discipline that produces
evidence used in public health
Inform policy
Policy 1. a principle or
course of action chosen to
guide decision making
2. prudent management
Source: Webster’s Dictionary
Public Health Policy:
Lessons from 1981 CDC EIS
Conference
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Restaurant and health care workers should
wash their hands
Thoroughly clean surgical instruments
Prepare & store food appropriately
Remove a particular tampon from market
Keep sewage out of drinking water
Don’t smoke cow manure
Stay away from active volcanoes
Examples of Public Health Policy
(Continued)
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Pandemic flu vaccination—Swine flu
Promotion of healthy lifestyle
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Smoking cessation
Diet & exercise
Seat belts & motorcycle helmet use
HIV & STD prevention
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Abstinence-only vs. comprehensive sex education
Harm reduction: Needle/syringe exchange for HIV
prevention
Public health policy:
The plot thickens
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Scientific uncertainty
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Competing values
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Moral, ethical, religious, cultural…
Limited resources
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“We need more data…”
Setting priorities
The role of government
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Federal, state, local
Government, business, families, faith groups,
NGOs, CBOs…
Requisites for Effective & Sustainable Policy
Judging the value
of our purpose
SUBSTANCE
Evidence / Science
Investing our purpose
with legitimacy and
support
POLITICS
Executive, Legislature,
Media, Public,
Constituents
Assuring our capabilities
for achieving our desired
purpose
ADMINISTRATION
Fiscal, Human and Other
Resources
Adapted from Mark Moore, Creating Public Value, Strategic Management in
Government, Harvard Univ Press, 1995.
Courtesy of Lydia Ogden MPP, CDC
“How shall…officials, who are
not themselves expert, deal
with…policy questions that are
based...on highly technical and
complex…knowledge-especially when that knowledge
is speculative, or hotly debated,
or when “the facts” are so
uncertain? With how much
deference and…skepticism
should those…making policy
view..the scientists and
experts?”
Joseph A Califano, Jr.
Secretary, DHEW, 1978
Did they ask the right
questions?
What about study bias?
Did they pick the right
comparison group?
Do the findings make
sense?
What are the strengths
& limits of the study?
Are the findings
appropriately
interpreted?
Image source: http://www.mtholyoke.edu/
Public Health Disciplines

Administration
Behavioral sciences
Communication
Economics

Epidemiology
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Ethics
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Environmental health
Evaluation
Health care professions
Geography
Management
Policy analysis
Statistics
“Are you just pissing and moaning, or can you verify what you’re saying with data?”
Source: The New Yorker