Comment:

Clinical quality measures need to address the concept of a Principal Diagnosis defined by statute as the coded diagnosis/problem established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care. The roles provided do not directly address principal diagnosis. FHIR tracker (https://gforge.hl7.org/gf/project/fhir/tracker/?action=TrackerItemEdit&tracker_item_id=10544) suggest that encounter-primaryDiagnosis and encounter-relatedCondition extensions will be removed as they are redundant with the core resource (using Encounter,diagnosis.role and Encounter.diagnosis.rank. However, the extension remains. And the example in Encounter.diagnosis.role does not address principal diagnosis. Encounter.diagnosis.role should include an example for definiing Principal diagnosis (e.g., role = billing diagnosis AND rank = 1, or role = discharge diagnosis AND rank = 1. Alternatively, add a role of "principalDiagnosis" to enable clinical quality measures and clinical decision support.

Summary:

Add example to Encounter.diagnosis.rol to address principal diagnosis for an Encounter as noted in the comment provided (or add an additional role of principalDiagnosis).