Rapid Assessment and Characterization of Environmental Risks RACER A New Software Tool Gary M' Marsh

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Rapid Assessment and Characterization of
Environmental Risks (RACER) - A New Software
Tool -Gary M. Marsh, Ph.D.Michael Cunningham,
M.S.Department of BiostatisticsGraduate School
of Public HealthPittsburgh Environmental
Summit - April 18, 2007
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Problem - Approach

• Under what conditions and to what extent can we
  detect elevations in the background rate of
  disease that were truly caused by an
  environmental exposure?
• To provide a web-based software tool that will
  enable public health officials and others to
  evaluate feasibility of conducting health
  tracking activities or targeted investigations

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Feasibility Factors (Statistical)

• The background rate of the disease under study
  (i.e., the rate in the unexposed population)
  
• The overall size of the potentially exposed
  population
• The proportion of the population that is exposed
  to varying levels of the environmental hazard
• The relative potencies of the various levels of
  exposure to elevate the background rate of
  disease
• Observation time of exposed subpopulations and
  latency period of disease under study

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Conceptual Model Airborne Exposure to Point
Source with Proportion of Subpopulations Exposed
Downwind of Source
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Example 1 80 Statistical Power to Detect
1.3-Fold Excess Reached in 2.5 Years
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Example 2 Power as Function of MDRR and Time
Period
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Example 3 Power as a Function of Exposed (ew)
and Time (years) - Comparison of 4 Plots
RRee 1.2
RRee 1.4
RRee 1.6
RRee 1.8
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Possible Future RACER Enhancements

• Indirect and direct standardization procedures
• Extend standardization to multiple factors
• Account for geographic population mobility
• Time dependent exposure-elevated relative risks
• Account for latency/incubation period of health
  endpoints
• Statistical methods for spatial (clustered) data

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Acknowledgements

The investigators wish to thank the following
groups for their support and guidance Centers
for Disease Control and Prevention Environmental
Public Health Tracking Program Grant
5U19EH000103-02 (Academic Partners for
Excellence in Environmental Public Health
Tracking) University of Pittsburgh Academic
Consortium for Excellence in Environmental Public
Health Tracking (UPACE-EPHT) (a
collaboration with Drexel University)