There is a lot of discussion on Self-Sovereign Identity partly as it is a "Distributed Ledger Technology".
There is a lot of discussion on Verifiable Claims, often used within Self-Sovereign Identity (Sovrin).
And there is a lot of concerns in medical care about Patient matching.
Obtaining medical records is a nearly impossible task. As you age, this becomes more difficult due to the number of Health Care Providers and the subordinate Health Care Providers involved with Health Care.
There is no one with a complete EMR of any kind.
Medicare/Medicaid and the Office of the National Coordinator for Health Information Technology (ONC) has recognized this as an issue and has offered incentives for using a interoperable Electronic Health Record.
Unfortunately, the Health Insurance Portability and Accountability Act (HIPAA) which were supposed to help with this has an Unintended consequence hampering due to the Regulatory Agencies involvement and the poor interpretation of the HIPAA Privacy Rule.
Integration of Fast Healthcare Interoperability Resources (FHIR) APIs using Verifiable Claims and the concepts within Self-Sovereign Identity provides a possible solution.
If we used a Personal Health Record and techniques within Self-Sovereign Identity, and Verifiable Claims then Patient matching becomes a non-issue. The Patient shares and revokess data from any Health Care Provider they desire.
Identifier registry - Mediates the creation and verification of subject identifiers.