Leveraging a Terminology Service to Facilitate Semantic Interoperability for Continuity of Care: A Sri Lankan Perspective

Sri Lanka’s digital health ecosystem is characterized by multiple heterogeneous Electronic Medical Record (EMR) systems operating in silos, limiting continuity of care. While HL7 FHIR-based data exchange with the National Electronic Health Record (NEHR) is being utilized to achieve syntactic interoperability, semantic interoperability remains constrained due to use of non-standardized clinical terminologies across EMRs. This case study describes the experience of leveraging a terminology service to standardize locally used clinical data and enable semantic interoperability in a low-resource setting. An OpenHIE-aligned architecture was implemented using Open Concept Lab (OCL) online as the terminology service, Open Health Information Mediator (OpenHIM) as the interoperability layer and HapiFHIR as a health data store. Locally defined value-sets for presenting complaints, diagnoses, medications, procedures, and investigations were extracted from multiple national EMRs, consolidated, and mapped to well recognized international terminology standards including SNOMED-GPS and LOINC through a multi-stakeholder process. The implementation resulted in creation of four terminology sources, 17 collections, 3,169 concepts, and 1,247 mappings, validated through national Connectathons. A mapping mediator was used for the transformation of local or free-text inputs into coded terminology prior to persistence in the NEHR, ensuring semantic consistency while preserving original data. The findings demonstrate that terminology mapping using open-source, OpenHIE-aligned technologies is a feasible approach for enabling semantic interoperability in low-resource settings. However, long-term sustainability requires adoption of standardized terminologies at the point of data capture, strengthened governance mechanisms, and continued capacity building.