In prior implementations we had developed an extension on MeasureReport.subject that was subsequently removed.  During Connectathon testing, we discovered that removing that extension increases the processing load on systems that might perform analysis on the reports based on geo-location.

That extension is defined below:

Extension: GeoLocation
Title: "Extension Attributes to associate with a Location Reference to simplify Geographic search"
Mixins: SanerStructureDefinitionContent
Description: """This is essentially a database denormalization that facilitates search by Geographics coordinates on a location.
It enables a FHIR Server to implement search on a MeasureReport by GeoLocation using an extension.
The extension is purposefully designed to duplicate the existing [FHIR GeoLocation Extension](http://hl7.org/fhir/StructureDefinition/geolocation)
in the hope that it could eventually be absorbed by that extension."""

• extension contains latitude 1..1 and longitude 1..1
• extension[latitude] ^short = "Like [geolocation:latitude](http://hl7.org/fhir/extension-geolocation-definitions.html#geolocation.Extension.extension:latitude)"
• extension[latitude].value[x] only decimal
• extension[longitude] ^short = "Like [geolocation:longitude](http://hl7.org/fhir/extension-geolocation-definitions.html#geolocation.Extension.extension:longitude)"
• extension[longitude].value[x] only decimal

An alterative that will accomplish the same goal (and a little more) would be to create an extension that allowed an Address to be added to the reference.  To get to GeoLocation, the existing http://www.hl7.org/fhir/extension-geolocation.html could be added to the Address content in that extension.  This enables reuse of the existing GeoLocation extension, but add a cost of additional complexity for accessing the information.