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The Use of Epidemiologic Methods for Surveillance of Chronic Disease and Linkage of Environmental Hazards and health Outcomes

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					          University of Pittsburgh
      Graduate School of Public Health
   Academic Consortium for Excellence in
Environmental Public Health Tracking (UPACE-
                   EPHT)

    Can the Concept of Environmental
     Public Health Tracking Work in a
            Real Life Setting?

          Evelyn Talbott, DrPH, MPH

               January 31, 2006

                                               1
       National Environmental Public Health
                 Tracking Network

• Institute of Medicine (1988) noted that “the removal
  of environmental health authority from public health
  agencies has led to fragmented responsibility, lack
  of coordination, and inadequate attention to the
  health dimensions of environmental problems.”
• In 2001, the Pew Environmental Health Commission
  issued the report “America’s Environmental Health
  Gap: Why the Country Needs a Nationwide Health
  Tracking Network”, which stated that “the existing
  environmental health system is neither adequate nor
  well organized, recommended the creation of a
  Nationwide Health Tracking Network for disease and
  exposures.”

                                                         2
      National Environmental Public Health
                Tracking Network


• In fiscal year 2002, Congress provided CDC
  with funding of $17.5 million to do the
  following:

  – begin developing a nationwide environmental
    public health tracking network
  – develop capacity in environmental health within
    state and local health departments.

• Several state and local health departments,
  and universities were funded to build
  capacity in environmental health
                                                      3
4
5
        University of Pittsburgh/Drexel University
      Environmental Public Health Academic Partner
                 (Consortium) Overview

• “…uniquely positioned to broaden resource coverage for
  public health agencies in the northeastern corridor and across
  the nation…”

• “…and to act as an academic partner in a local, state, regional
  and national initiative to facilitate environmental capacity
  building, to evaluate existing surveillance methodologies and
  to develop and/or extend innovative strategies and tools to link
  hazards, exposures and health effects databases.”

•    “…participate in the development and/or modification of easily
    accessible, web-based applications for environmental health
    tracking, disease surveillance and data linkage by public health
    agency personnel…”
                                                                       6
              Environmental Public Health Tracking Network:
              Data Acquisition and Linkage: The Challenge

    Hazard databases: TRI,
    EPA air toxics, water
    quality measures, etc.

   Exposure databases:
   Biomonitoring information-
   Blood lead, arsenic, mercury,
   etc.
   Health outcomes databases:
   Mortality, morbidity
   (admissions, ED visits, office
   visits, medication usage, etc)

   Data linkage strategies

   Evaluate associations

Direct Research and Interventions                             7
    Can the Concept of Environmental
 Public Health Tracking Work in a Real Life
                  Setting?

• The question remains, at the end of this
  major effort, will the Environmental Public
  Health Tracking Network be able to track
  and link hazards, exposures and outcomes
  in a way that will have real life effects and
  impact on the public health of our
  communities?

                                                  8
    Can the Concept of Environmental
 Public Health Tracking Work in a Real Life
                  Setting?

• Moreover, will investigators be able to
  establish new relationships between
  environmental hazards and disease?

• Perhaps most importantly, will public health
  professionals have the ability to intervene
  upon these conditions to make a
  difference?
                                              9
    Can the Concept of Environmental
 Public Health Tracking Work in a Real Life
                  Setting?

• The two primary objectives of the
  nationwide health tracking are to:

• 1) Identify populations at risk and respond
  to outbreaks, clusters, and emerging
  threats and
• 2) Establish the relationship between
  environmental hazards and disease

                                                10
     Can the Concept of Environmental
  Public Health Tracking Work in a Real Life
                   Setting?

• At the heart of a national surveillance and
  tracking system is the context of “Who”
  and “What” to track.
• It is unrealistic to think each citizen will
  wear a personal monitor for every potential
  pollutant and a companion biomonitoring
  device that would detect an enhanced body
  burden.

                                                 11
    Can the Concept of Environmental
 Public Health Tracking Work in a Real Life
                  Setting?
• The second best design for a national
  surveillance system is that which takes
  advantage of a common area and
  population, linking variables which share
  similar time, and space coordinates. An
  example of time, person and place are the
  hallmarks of epidemiological
  investigations.

                                              12
    Can the Concept of Environmental
 Public Health Tracking Work in a Real Life
                  Setting?

• These “ecological studies” are often
  used to consider the trends of disease
  over time in a certain population or
  cohort and are hypothesis generating
  investigations .


                                              13
    Can the Concept of Environmental
 Public Health Tracking Work in a Real Life
                  Setting?

• In ecologic studies, the group rather than
  the individual is the unit of comparison.
• Disease rates in various groups, usually
  defined as a group living within specific
  geographic areas are compared.
• The variation in rates from one area to
  another may be explained by correlations
  between these rates and risk factors or
  “exposures” distinct to certain areas.
                                               14
       Can the Concept of Environmental
    Public Health Tracking Work in a Real Life
                     Setting?

• These studies are constrained by the use of
  group rates of disease or hospitalizations as
  well as area –wide averages of hazard
  exposure measures.

• Linkage is by way of census tract, geocode,
  Zip code or county.


                                                  15
      Can the Concept of Environmental
   Public Health Tracking Work in a Real Life
                    Setting?

• The data are often available in electronic
  format and de-identified, making linkage of
  both the hazard/ environmental exposure and
  the outcome feasible.

• Emergency room visits and admissions,
  hospitalizations, data from cancer registries,
  etc offer significant potential for such
  ecological investigations.
                                                16
      Can the Concept of Environmental
   Public Health Tracking Work in a Real Life
                    Setting?
• What examples currently exist that show that
  ecological studies have utility in the EPHT
  mode?

• Examples of ecological studies which have
  yielded important information on an
  exposure and outcome are available in the
  literature; however most have been
  conducted within the context of a research
  study.                                        17
        Can the Concept of Environmental
     Public Health Tracking Work in a Real Life
                      Setting?

• Investigators obtain the necessary data on
  confounders within a disease-exposure relationship.

• Confounders are risk factors which if present can
  affect both exposure and outcome.

• Pancreatic cancer has been linked to cigarette
  smoking; however, heavy cigarette smoking is often
  related to heavy coffee drinking.

• If one does not control for cigarette smoking, coffee
  intake would arise as a significant risk factor.
                                                          18
       Can the Concept of Environmental
    Public Health Tracking Work in a Real Life
                     Setting?

• Another classic example is that of the effect of age
  of a population on chronic disease mortality rates.

• Cancer rates increase exponentially as we age. If
  there are two communities with vastly different age
  distributions, one community will appear to be
  riddled with higher rates of disease when in reality
  the age difference is the defining factor

• Age adjustment should have been carried out prior
  to the comparison.
                                                         19
      Can the Concept of Environmental
   Public Health Tracking Work in a Real Life
                    Setting?

• The combination of a deliberate and
  thoughtful consideration of the rationale for
  the study as well as adjustment for
  confounders takes time

• In the case of surveillance, access to
  sufficient data might be limited.


                                                  20
      Can the Concept of Environmental
   Public Health Tracking Work in a Real Life
                    Setting?

• Problems related to misinterpretation can be avoided
  if the age, race and gender distribution of a
  population are known and a large enough sample
  size is available for study.

• Moreover, access to detailed census information on
  the area under investigation and careful
  consideration of the area of exposure will help
  ensure the most specificity of representation of the
  exposure to the exposed population.

                                                     21
                   Examples of
   Public Health Tracking in a Real Life Setting


• In 1990 Arden Pope was able to obtain
  hospitalization admission data on pulmonary and
  cardiovascular outcomes in children and adults
  related to a steel mill in the area which had ceased
  operation for a discrete period of time.

• A precipitous drop occurred in the number of
  hospitalizations (25%) during closure with an
  increase in rates and numbers when the plant
  reopened.
                                                         22
                Examples of
Public Health Tracking in a Real Life Setting

                         Number of Hospital Inpatient Admissions
                 for Selected Respiratory Diseases in Children Ages 0-17
      Utah Valley, Utah across Time Periods with Geneva Steel Mill Open and Closed
                      1985-1988 Winter Months (December-February)
                                        (from data in Pope CA, AJPH 1989; 79:623-628.


                              80
                              70
         Number of Hospital




                              60
            Admissions




                              50
                              40
                              30
                              20
                              10
                               0
                                   1985/86 (Mill Open) 1986/87 (Mill Closed)        1987/88 (Mill Open)
                                     Mean PM10=90        Mean PM10=51                 Mean PM10=84
                                       Bronchitis/Asthma Ages 0-17   Pneumonia/Pleurisy Ages 0-17


                                                                                                    Figure 1
                                                                                                               23
                       Examples of
    Public Health Tracking in a Real Life Setting

• Another example is the now famous decrement in
  blood lead levels in the late 1970’s as a result of the
  removal of lead from gasoline.

• The EPA ruling in l975 resulted in the removal of lead
  in gasoline for all noncommercial vehicles

• The result of this removal was 37% decrease in
  average blood levels in the U.S. from February l976
  through February l980.

                                                            24
Examples of Public Health Tracking
     in a Real Life Setting




                                     25
                Examples of
Public Health Tracking in a Real Life Setting

An additional example is related to
aeroallergens and pollen counts in a defined
area as related to childhood asthma
exacerbations. Such evidence can provide an
intervention strategy in a defined
neighborhood or municipality.



                                            26
Risk Ratios of asthma admissions and ER
      visits by level / type of pollen




     Clinical and Experimental Allergy, 2000, Volume 30, 1724-1732
                                                              27
    Can the Concept of Environmental
 Public Health Tracking Work in a Real Life
                  Setting?

They are very powerful examples because
they illustrate that our environment has
important effects on our well being.




                                              28
                Examples of
Public Health Tracking in a Real Life Setting

These examples of ecological studies
demonstrate that for a given group of
subjects, when the “pollutant” in question
was removed or reduced, a concomitant
reduction in a biological response
(biomarker of exposure) (in this case blood
lead levels) or health outcome (reduction in
hospital admissions for asthma/ respiratory
illnesses) occurred.
                                               29
       Can the Concept of Environmental
    Public Health Tracking Work in a Real Life
                     Setting?

. The ecological design just described must be
 viewed in the context of several important
 pitfalls. When using data on group rates
 and group exposures, a major issue is one of
 defining the true “exposed population” and
 “exposed area”.



                                                 30
    Can the Concept of Environmental
 Public Health Tracking Work in a Real Life
                  Setting?

Within a given county there may be varying
levels of an air pollutant which is dependent
upon topography and wind direction and the
differences in exposure levels among
subgroups of sensitive populations may not
provide adequate sample size to quantify the
response to such an exposure

                                              31
      Can the Concept of Environmental
   Public Health Tracking Work in a Real Life
                    Setting?

• What alternatives does an environmental public
  health tracking network offer in such cases?

• Biomonitoring of unique and/or sensitive subsets of
  the population is one way to help target groups more
  likely to be affected by an exposure. Moreover, when
  a unique exposure occurs in more than one locale, a
  national tracking program would have the ability to
  link this information for multiple sites.

                                                    32
       Can the Concept of Environmental
    Public Health Tracking Work in a Real Life
                     Setting?

• Can the concept of the Environmental Public Health
  Tracking work in a real life setting?
• The answer is an unqualified “Yes”, given
  appropriate cooperation from participating states
  and city health departments and the ability to link
  high quality data on hazards, exposures and
  outcomes.


                                                        33
        Can the Concept of Environmental
     Public Health Tracking Work in a Real Life
                      Setting?

• The EPHTN has the potential to yield important new
  information on the risk factors and environmental
  triggers that have remained elusive for a number of
  chronic diseases and conditions.

• The ability to link hazards and exposures to disease
  endpoints in a responsible way is a critical step in
  the protection of our nation’s public health.



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