Navigating Technical Challenges in FHIR-Based Patient Reported Outcome Measures: Towards Interoperability with the MII PRO Core Dataset.

INTRODUCTION: Patient-Reported Outcome Measures (PROMs) are vital for capturing subjective clinical data, yet electronic PROM tools often suffer from fragmentation and siloed data storage. To facilitate cross-site data sharing, large-scale interoperability must be integrated into these digital tools. METHODS: We developed a HL7 Fast Healthcare Interoperability Resources (FHIR) system for Mobile Patient Survey (MoPat), which supports multiple versions and is designed to integrate PROMs into various FHIR-based infrastructures. To evaluate the system, we used the Medical Informatics Initiative (MII) PRO core dataset as a use-case. This evaluation aimed to assess usability for MII projects and identify technical or functional gaps. RESULTS: Questionnaires from the PRO core dataset were imported into MoPat without technical errors, but the import process stripped the associated score-calculation logic and code-system definitions, resulting in a loss of that semantic information in the MoPat data model. DISCUSSION: The results show that the technical integration of MoPat with the MII core dataset was successful, but semantic annotation remains a major challenge: the loss of score-calculation logic and of the original code-system mappings limit full data-standardization. This reveals tension between highly regulated data collection software and research-focused data structures that prioritize more granular detail. CONCLUSION: This study validates the potential of electronic PROM tools to adopt standards like the MII core dataset. Future development should prioritize the inclusion of standardized code systems to further enhance semantic interoperability.