The Profile Specific Implementation Guidance for the MedicationAdherence extension indicates:The informationSource subextension lists several profile references. Although none of the informationSource references are flagged as Must Support, the server SHALLsupport at least one of them.

The data type for informationSource is a reference to US Core Profiles for Practitioner, PractitionerRole, Patient and RelatedPerson with expectations these references will conform to the US Core Profiles and return all Must Support information about a practitioner or related person.MedicationAdherence is documented as part of an intake process on admittance to a clinical setting during medication reconciliation. When adherence is documented, the role of the information source is the most influential piece of information, not the name of the related person, nurse, doctor, or pharmacist that was the source of information. Additionally, the source of information may be from someone outside of the system and capturing the name, address, telecom information about the person places an additional burden on systems to make that information required.Therefore, we suggest using a data type of codeableReference where the role of the source can be documented as a minimum requirement without the specific name, location or telecom details of the Practitioner or RelatedPerson. This would establish a more appropriate minimum bar for the Profile given the intent of the information and normal clinical workflows for recording it.