1. Prototype Statewide Interactive Mapping Service Preterm birth, 2000-2002 Environmental Health Investigations Branch California Department of Health Services

2. 2 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

3. 3 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

4. 4 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

5. 5 Representing disease risk Choropleth 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 CODERATE 946128.3% 947059.1% 946107.2% 947019.9%

6. 6 Interactive Mapping

7. 7

8. 8

9. 9

10. 10 Interactive Mapping

11. 11 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 – 19972002 – 2003 1998 – 19992004 – 2005 2000 – 20012005 – 2006

12. 12 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?

13. 13 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.

14. 14 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?