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Prototype Statewide Interactive Mapping Service
Preterm birth, 2000-2002
Environmental Health Investigations Branch
California Department of Health Services
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High-resolution, continuous health outcome maps
• Tap into narratives that stakeholders want told
– People identify communities, including vulnerable communities, by their geography
– Policy makers are invested in understanding the geography of health problems and the resources to address them
– Concerns about environmental impacts on health are often expressed in spatial terms
• Can be an effective communication tool
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Needs for a mapping function• Flexibility of views
• Interactive
• Accessible without specialized technology
• Complete protection of confidentiality
• Provides two kinds of information:
– Rate of health outcome
– Whether rate is significantly elevated relative to a standard
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Representing disease risk• Each map has potential to mislead
• Which map facilitates the most productive conversations?
Asthma hospitalizations by ZIP code
Asthma ER visits by density estimation
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Representing disease riskChoropleth
• Data from this map corresponds directly to what you would get from a table
Continuous
• Uses point (address level) data
• Risk varies continously (→more intuitive)
• A mathematical function is used to represent rate “at a point” (→less intuitive?)
• Example: Spatial loess function
ZIP CODE RATE
94612 8.3%
94705 9.1%
94610 7.2%
94701 9.9%
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Interactive Mapping
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Interactive Mapping
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Interactive Mapping
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Interactive Mapping
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Interactive Mapping
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Future plans• Presently only have prototype; ultimately want
publicly-viewable maps with supporting text
• Revise calculation algorithm to eliminate “phantom” hot spots, streamline computation
• Birth outcomes: – Preterm birth
– Low birthweight at term
• Cohorts:1996 – 1997 2002 – 20031998 – 1999 2004 – 20052000 – 2001 2005 – 2006
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Considerations• This works for non-aggregated point
data
• Both cases and controls (ie, numerator and denominator) must be point data
• If the outcome rate is based on a birth cohort (preterm birth, SIDS, pediatric cancers, birth defects), controls can be birth records
• For outcomes among older children or adults, is there a source of control data?
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Considerations• This approach may not calculate meaningful
rates if the outcome of interest is very rare
• Perhaps in this case a continuous rate surface doesn’t really interest us, but rather the detection of clusters?
• Cluster detection should be considered a different category of functions
– Statistical significance contours of loess
– SatScan
– SpatClus
– Etc.
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Questions for TIAG• Would you or your constituents ever use a
service like this? If so, how?
• What other information or services would be necessary to make them useful?
– Supporting/explanatory material?
– Tabular data?
• What other health data would it make sense to display like this?
– What outcomes are most important?
– What outcomes do we have point data for?