Building on the USCoreLaboratoryResultObservationProfile is understandable because many element bindings from that profile are appropriate and desirable to carry forward (e.g. Observation.code to LOINC), but having explicitly deriving from it requires that the Observation.category = laboratory. This is terribly confusing, and would wreak havoc in Health IT systems and their users because functioning observations would be displayed/processed as lab tests .

We recommend that this IG remove its binding to USCoreLaboratoryResultObservationProfile. US Core has not defined a generic "Observation" profiles yet, but there are some specific non-lab profiles for Smoking Status, and other important measures (head circumference, pulse ox, etc). We believe the best approach would be to look across the various US Core profiles on Observation and replicate all the constraints that make sense for these observations. That is, make this profile as functionally close as possible to them, but don't actually establish a dependency on it.