Several years ago, our public health statistics team divided the State into 126 Community Health Analysis Areas to help us analyze data for various disease monitoring programs. The initial trigger to develop the CHAAs was a 1988 law that directed the ADHS to use the data in the cancer registry to identify areas and populations that need investigation. Until recently, the state-collected cancer data was not complete enough to looks at rates on a relatively small geographic scale, limiting analysis to the county level only. Once we had enough data to meet the legislative mandate to report on rates across the state we developed CHAAs to present our data at a geographic scale smaller than the county level.
We created CHAAs by modifying the 126 Primary Care Areas used by the ADHS program for Health Systems Development. PCAs have been used to characterize the health needs of communities for many years; however, the PCAs didn’t provide all the coverage and detail that we require for every part of the state, so we developed the CHAAs to more closely align to the growing rural communities and to Phoenix’s villages.
Each CHAA is built from US 2000 Census Block Groups. These Block Groups are relatively small geographic regions of the state. A typical CHAA contains approximately 21,500 residents. But, because of the scattered pattern of development in Arizona they range widely in population, from 5,000 to 190,000 persons. The use of the relatively small Block Groups gives us the ability to aggregate data at a variety of sizes, from the Block Group level up to the CHAA level that we use in analysis. A CHAA in the highly urbanized areas of Maricopa County contains approximately 100,000 persons. The average rural CHAA contains approximately 10,000 persons.
You’ll be hearing alot more about CHAAs in the very near future.