Transforming a Leigh Syndrome Patient Registry to the OMOP Common Data Model

Background: Patient- and caregiver-reported registries play a critical role in rare disease research, yet their heterogeneity and lack of interoperability limit reuse across studies and regulatory contexts. The Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM) provides a standardized framework to support harmonization and secondary use of observational data. Methods: We describe the transformation of a global, patient- and caregiver-reported Leigh syndrome registry led by Cure Mito Foundation into the OMOP CDM. The process included curation of registry variables and terms to standardized vocabularies, implementing extract–transform–load (ETL) procedures, and evaluating data quality using established OMOP validation and verification checks across conformance, completeness, and plausibility parameters. Results: The registry data was successfully aligned with the OMOP CDM. Key challenges reflected the non–EHR-derived, non–visit-based structure of the registry, which constrained use of certain OMOP tools, while key benefits included successful mapping to standardized vocabularies and harmonization of patient- and caregiver-reported data within the OMOP CDM. Conclusions: This work demonstrates the feasibility of transforming a patient- and caregiver-reported rare disease registry into the OMOP CDM while maintaining transparency regarding structural limitations. Standardizing patient-led registries such as the Cure Mito registry enhances interoperability and supports broader reuse for observational research, trial design, and regulatory-relevant analyses in rare diseases.