The number of countries utilizing Systematized Nomenclature of Medicine Clinical Terms (SNOMED CT) has increased approximately fivefold over 16 years, from 9 to 48 in 2023 [3]. Seventeen Organization for Economic Co-operation and Development (OECD) member countries have reported developing plans to enhance the interoperability of electronic medical records (EMRs). Additionally, 15 OECD member countries indicated plans to adopt the HL7 Fast Healthcare Interoperability Resource (FHIR) Standard, according to a 2021 report [4]. The United States, Canada, the United Kingdom, Australia, the Netherlands, Finland, and Switzerland have incorporated HL7 FHIR release 4 (R4)-based transmission standards into their national projects [4]. More than 20 European countries operate national PHR systems, and 22 countries implement an interoperability framework based on international standards such as SNOMED-CT, HL7 FHIR, and HL7 CDA R2 [5]. According to a survey conducted by HL7 International across 32 countries, 13 countries have established a national FHIR data model, and another 13 are in the process of developing one [6].

In 2004, the Institute of Medicine in the United States emphasized the need for a national health information infrastructure, encompassing systems, technologies, applications, standards, and policies, to improve patient safety. They also recommended that the federal government provide various support policies, including financial assistance, to establish this infrastructure [2]. Additionally, they advised healthcare providers to invest in EHRs. These recommendations continue to guide U.S. health information policy. The Office of the National Coordinator for Health Information Technology (ONC), created by the Health Information Technology for Economic and Clinical Health Act in 2009, has since implemented a health data standardization management system. Starting in 2010, the Meaningful Use (MU) incentive program for EHRs was launched to encourage the adoption and exchange of health information [7]. The 21st Century Cures Act, passed in 2016, further promotes the interoperability of electronic health information and includes regulations on information blocking, as well as provisions to standardize data usage. This act came into effect in 2021. In 2018, the MU incentive program for EHRs transitioned to the Promoting Interoperability program and was integrated into the payment system [8]. Following the enactment of the 21st Century Cures Act, separate standardization committees were consolidated and are now operational. Additionally, the Health Information Technology Advisory Committee, a public-private partnership advisory committee, was established to provide the ONC with recommendations based on the Health IT strategic plan, aiming to establish an ONC-centered standardization promotion system. The transmission and exchange of electronic health information utilize a standard known as the US Core Data for Interoperability (USCDI) via an API using the HL7 FHIR. The USCDI, defined by the ONC, is a standardized set of health data classes and constituent data elements for nationwide interoperable health information exchange [9]. It was officially adopted as a standard in the ONC Cures Act Final Rule in May 2020 and is updated annually. According to a 2021 survey, seven out of 10 hospitals enabled patients to access their health information using applications or software based on API technology. Furthermore, patients were able to review their clinical records through hospital portals at a rate of over 80% [10].

Given the global trend toward digital transformation in healthcare, Korea has invested significantly in digital health technologies. Moreover, the rapid aging of the population and the COVID-19 pandemic have accelerated the development of an ecosystem that supports effective health data sharing and utilization. This includes the formulation of policies aimed at enhancing public health and stimulating growth in related industries. Consequently, laws and regulations concerning health data have been amended to facilitate their utilization.

In 2010, the Center for Interoperable Electronic Healthcare Record introduced a national terminology standard known as the Korea Standard Terminology of Medicine (KOSTOM). By 2014, it was recognized as a national health data standard and underwent irregular revisions until the end of 2022. The use of KOSTOM was optional, and only a few related national projects were in place, resulting in very low adoption rates [11]. According to a national health informatization survey conducted by the MOHW in 2020, 78% of tertiary hospitals participated in the Standard-based HIE project. However, only 32% of hospital-level medical institutions were involved [12]. Among tertiary hospitals, the adoption rate for Clinical Document Architecture (CDA) was 21%, while the adoption rate for FHIR stood at just 10% (Figure 1).

The MOHW oversees three principal projects related to health data standards: the EMR certification system, the HIE project, and a national PHR project known as MyHealthWay. Previously, no national transmission standards were in place, leading to the creation of individual standards that complicated the integration of national projects. Hospitals involved in these projects are required to adhere to various standards. Consequently, there is an increasing demand for a national health standard policy and advanced transmission standard technology to facilitate the use and sharing of health data.

To address the limitations of existing standardization policies, promote interoperability-based standardization, and establish a governance system for standardization, the Health Data Standardization Taskforce was formed. This taskforce aimed to propose a new health data standardization policy.

The Health Data Standardization Taskforce, established in December 2022, is dedicated to setting standards for terminology and transmission technology. It also focuses on developing a standardization roadmap and an implementation strategy for use and dissemination in healthcare. The taskforce, co-chaired by representatives from both private and government agencies, includes 23 members. These members represent a diverse group of stakeholders from the medical and industrial sectors, including chief medical information officers, leaders in medical informatics and health information technology, and representatives from medical academia and public health agencies. Within the taskforce, three working groups (WGs) were formed: the CDI WG, the Next-Generation Technology WG, and the Governance WG, as depicted in Figure 2. The specific roles of these WGs are detailed in Figure 2.

The taskforce team evaluated the current status of health data standardization and discussed its vision, mission, and strategies. Over the course of 6 months, 37 meetings were held with a total attendance of 1,078 participants. During these meetings, a field-demand-based standardization promotion strategy was developed, along with health data standards (KR CDI, KR Core), and a plan to support the widespread adoption of these standards was formulated. In line with the global trend towards adopting international standards, the decision was made to discontinue updates to KOSTOM. By benchmarking advanced standardization models and gathering feedback from the medical community, key exchange items (KR CDI) and detailed specifications for their implementation (KR Core) were developed and subsequently announced. These standards are mandatory for projects based on standardization. The specific activities are depicted in Figures 2 and 3.

The taskforce proposed a 5-year mid- to long-term strategy along with detailed tasks to promote patient-centered HIE. Additionally, it was suggested that these tasks be undertaken by a permanent standardization organization. Following the discussions, the taskforce established the vision for health data standardization as “promoting public health improvement through standards-based digital innovation” and defined the mission as “creating a digital health environment where people can access and share health information when needed.”

Three strategies and 11 major tasks were selected (Figure 3). Strategy 1 focuses on the “development of national standards to strengthen interoperability.” This includes the creation of the KR CDI, HL7 FHIR KR Core, health data standard notice, and addressing the needs of next-generation health data standardization. Strategy 2 aims to enhance data utilization through the establishment and diffusion of standards. This strategy includes tasks such as developing a plan for the establishment and dissemination of standard notices in the field, creating a support system for the field application of standardization, and setting up a standard diffusion and support platform. Strategy 3 centers on the “establishment of sustainable standardization governance.” It involves strengthening the standardization governance system, formulating a standardization promotion strategy, enhancing international cooperation, and developing expertise in standards.

To strengthen the standardized governance system, a Health Data Standardization Promotion Committee has been proposed as a permanent body to deliberate and decide on health data standardization policies. This committee includes experts from the medical field, industry, academia, and government agencies. It will develop a strategy for standard development and diffusion, oriented toward international standards to enhance the interoperability of health data. Additionally, the committee will prepare a standardization diffusion plan through the gradual application of standards in standardization-based projects and establish a corresponding legal framework. The committee oversees the Governance WG, KR CDI WG, and Standard Technology WG, which facilitate standard development and policy promotion (Figure 4). The Industry Council and Standard Terminology Council will gather input from practitioners regarding the KR CDI, KR Core, and related topics.

The KR CDI comprises a set of standard classifications, items, and terminology required for the exchange of information, tailored for the interoperability of domestic health data. The designated exchange standard for the KR CDI is HL7 FHIR R4, which is implemented through the development and distribution of FHIR KR Core. HL7 FHIR facilitates a flexible architecture that supports existing paradigms such as messaging and document exchange. Moreover, it allows for expansion into various computing environments, including mobile and cloud, through the adoption of web-based technology. While HL7 FHIR is globally recognized for health data exchange, it provides only the foundational standards. To effectively utilize these standards, each country must develop its own detailed FHIR standards at a national level that are universally applicable and tailored to specific needs. Consequently, conducting case studies is essential. Several countries have already developed detailed national FHIR specifications that are reflective of their unique medical environments and have successfully applied them to various use cases (Table 1). As the exchange and utilization of health data become more prevalent in Korea, there is a pressing need to develop detailed FHIR specifications that are well-suited to the domestic medical environment. This necessitates the creation of a common core detailed standard (KR Core) that builds upon the KR CDI, the cornerstone of domestic interoperability (Figure 5).

The KR CDI was developed by reviewing the health data exchange items from existing domestic and international health data standard projects and by gathering feedback on the essential health data items needed for information sharing. For domestic projects, we examined the HIE project, the MyHealthWay project, the FHIR KR Core Draft developed in 2021 [13], and the second cycle of EMR certification standards (draft), and we also referred to the USCDI versions 1 through 3 (V1-3). The KR CDI draft was formulated and reviewed in January 2023, with input from stakeholders in the medical field. We identified two or more common classes and elements across health data projects. Several review consultations were then held with standard experts from the medical, academic, and industry sectors to discuss the feasibility of implementing the KR CDI, its suitability as a standard, and its integration with related standard projects. After finalizing the main content, as well as the class and item names, the development of KR CDI V1 was completed.

The KR CDI V1 consists of 14 classes (data classes), 77 items (data elements), item values (value sets), and specifies whether each item and item value is mandatory. A class groups related topics or items together. Items represent the smallest units defined for data exchange, while item values are sets of terms designed to convey the same meaning across different expressions, ensuring system interoperability. For instance, in the classes concerning diagnosis and chief complaint information, the items include the diagnosis date, diagnosis name, clinical status at diagnosis, date of the chief complaint, chief complaint name, and clinical status of the chief complaint (Table 2). The diagnosis date, name, and clinical status at diagnosis are mandatory. The KR CDI notice includes a detailed manual that provides examples of classes and items [14].

FHIR KR Core is the Korean version of FHIR’s Implementation Guide (IG). It is a comprehensive standard that specifies the minimum constraints on FHIR resources and APIs for exchanging domestic health data in line with the requirements of the KR CDI. In December 2021, after analyzing the detailed FHIR specifications from leading countries such as the US Core of the United States and the AU Base of Australia, the FHIR Core Draft version was developed. This version profiles items that are frequently used in the domestic healthcare environment among FHIR resources. After discussions on the KR CDI linkage, standard notice and management plan, FHIR security, and collaboration with HL7 Korea, the Next-Generation Technology WG officially released the FHIR KR Core v1 at the end of June 2023. The announcement and distribution of the FHIR KR Core were conducted through the official HL7 standard publishing process, in collaboration with HL7 Korea. The proposal for the FHIR KR Core standard was submitted via HL7 Korea (Ballot), and feedback was gathered through a two-week initial round of member voting (balloting). The final adjustments were made based on feedback from developers’ key concerns raised during the Connectathon process and the initial ballot review. Out of 55 eligible votes, excluding 6 abstentions, 47 votes (95%) supported the standard, surpassing the 60% threshold required for approval, leading to the official publication and approval of the FHIR KR Core.

In FHIR KR Core V1, 27 profiles based on FHIR R4 resources were defined (profiled) according to the KR CDI requirements (Table 3). The notice outlines the method for resource exchange via the FHIR API and specifies constraints to ensure compliance with the FHIR KR Core. Technical documents and manuals detailing the definitions and usage guidelines for the KR Core components are available through links and are presented on web pages that adhere to the HL7 standard template.

To ensure health data interoperability and foster an ecosystem for its utilization, the taskforce team updated the existing “Health Terminology Standard” notice to the “Health Data Terminology and Transmission Standard” notice. This revision incorporates key items related to the exchange of health data, including transmission technology and management systems. The revised notice now includes the KR CDI, FHIR KR Core, and a standard data management system (Figure 6). The United States’ standards development and management procedures are systematic and well-established. The standard management system was developed by referencing the US model. The US ONC operates the Standards Version Advancement Process to adopt and announce both current and future standards [15]. The latest versions of the USCDI and US Core are subject to a period for collecting public opinion, after which the approved standards are announced and implemented. Similarly, the revised notice will be updated by collecting feedback from stakeholders to develop standards. The completed standard notice revision (draft) will be presented to the committee, and the revised notice will be disseminated promptly. Detailed information about health data standards and the “Health Data Terminology and Transmission Standard” notice will be available on the Health Information Standards System website.