Recent literature demonstrates growing interest in integrating blockchain technologies with interoperability standards such as HL7 FHIR. Although several studies provide solid conceptual and architectural frameworks, most remain theoretical and lack validation in real clinical environments. For instance, Díaz and Kaschel (11) proposed a dual-channel Hyperledger Fabric architecture evaluated through Caliper, yet their work did not extend to clinical interfaces or FHIR integration. Similarly, Uddin et al. (10) developed a modular Fabric-based framework employing smart contracts, though their research focused primarily on system design rather than empirical testing.

From a security and access control perspective, Yaqub et al. (17) introduced a policy-based access control (PBAC) mechanism implemented with blockchain smart contracts, while Sonkamble et al. (13) presented the PCHDM Framework combining SPAKE, IPFS, and Fabric. Despite their technical rigor, neither of these solutions has undergone clinical or operational validation.

In the context of the Internet of Medical Things (IoMT), conceptual frameworks have been proposed to improve distributed management of Electronic Health Records (EHRs). Nkenyereye et al. (14) examined distributed nodes for EHR handling without providing a technical implementation, whereas Gulzar et al. (18) designed a theoretical model–BlockMed–leveraging artificial intelligence for HL7-FHIR translation, but without a deployable prototype.

Emerging studies have explored privacy and scalability through advanced technologies. Ma and Zhang (19) proposed integrating ZK-Rollup and IPFS for privacy-preserving medical records, while Pokharel et al. (1) investigated blockchain-based cybersecurity frameworks emphasizing compliance with HIPAA and GDPR. Similarly, Benaich et al. (20) expanded this line of research by incorporating post-quantum cryptography, decentralized autonomous organizations (DAOs), and artificial intelligence, though their results remain theoretical. Van Wensel and Seneviratne (21) further contributed by proposing a semantic approach that generates smart contracts from HL7-based Knowledge Graphs through an off-chain pipeline, yet their system has not achieved clinical interoperability.

Comprehensive analyses, such as the survey by Merhej et al. (22), offer systematic overviews of blockchain and AI integration in healthcare, identifying challenges related to scalability, interoperability, and regulatory compliance. In contrast, Carter et al. (23) made a more practical contribution through the “OpenPharma Blockchain on FHIR” framework, which employs Ethereum, FHIR standards, and voice biometrics to enable secure, read-only health data exchange while avoiding the storage of protected information on-chain.

In summary, current research establishes a solid theoretical and architectural foundation for combining blockchain and FHIR in healthcare. However, a notable gap persists: few studies provide fully integrated, functional implementations validated within clinical environments, highlighting the need for practical, interoperable, and empirically tested solutions.

Recent research has increasingly focused on integrating blockchain technology with HL7 FHIR to improve interoperability, security, and privacy in Electronic Health Records (EHRs). Bran et al. (24) proposed a framework that utilizes blockchain and IPFS for managing allergy and family history data, ensuring secure and interoperable record sharing. In a similar vein, Mauricio et al. (15) developed an architecture and web platform that facilitates the exchange of EHRs among diverse healthcare systems in Peru, without the need to modify existing legacy infrastructures. Uddin et al. (10) developed an architecture based on Hyperledger Fabric to ensure data integrity and decentralization in the management of medical records. Meanwhile, Sreejith et al. (12) presented an HL7 FHIR framework that combines GraphMap and blockchain-based authentication through smart contracts to enhance interoperability in e-health environments.

Recent studies have expanded efforts toward creating decentralized and semantically rich systems. Kim et al. (16) introduced a decentralized personal health record (PHR) management model that integrates personal data storage (PDS) and decentralized identifiers (DID), enabling users to have complete ownership of their data. Meanwhile, Van Wensel and Seneviratne (21) investigated the automated generation of smart contracts from semantic knowledge graphs, aiming to enhance compliance and alignment with standards such as HL7 FHIR. Likewise, Marfoglia et al. (25) proposed a modular pipeline for transforming clinical data into the FHIR format. This approach enhances semantic interoperability and promotes code reuse. Additionally, Gulzar et al. (18) introduced BlockMed, a framework that integrates blockchain technology with artificial intelligence to facilitate secure interoperability and automate the translation between HL7 and FHIR standards.

As shown in Table 1, Mauricio et al. (15) describe one of the few instances in Peru where an interoperable web application that utilizes HL7 FHIR and IPFS, supported by blockchain technology, has been developed, as detailed in Table 1. The system was validated in a simulated environment involving both doctors and patients, demonstrating promising results in terms of traceability and access control. However, its geographical reach is still limited, and the study does not yet address issues related to multi-node scalability or the potential for replication in real hospital settings.

Additionally, after conducting a systematic review of indexed databases such as Scopus, Web of Science, IEEE Xplore, and PubMed, using the search string: “(healthcare interoperability OR clinical data exchange OR EHR interoperability) AND (blockchain OR decentralized architecture OR Hyperledger Fabric OR smart contracts) AND (HL7 FHIR OR Fast Healthcare Interoperability Resources OR FHIR API) AND (web application OR functional implementation OR system prototype OR user validation),” the only relevant study identified was conducted by Mauricio, who developed an electronic health record system utilizing EHRs and blockchain technology. This study presented various architectures, designs, and prototypes (mockups). In contrast, this paper proposes a solution based on the FHIR standard that incorporates a more user-friendly interface. Additionally, it places special emphasis on information security, ensuring that user data can only be viewed and modified by entities authorized by the user.

WiraChain implements an Interoperability Architecture featuring an Immutable Audit Layer (see Figure 2), designed to ensure the secure and efficient exchange of clinical data. The system integrates React for developing responsive single-page interfaces and the .NET framework for orchestrating operations within a microservice-based environment, enabling robust integration, scalability, and high-performance processing. MySQL provides transactional consistency for identity and credential management, while Hyperledger Besu functions as an immutable audit ledger, ensuring full traceability and regulatory compliance (29).

We adopt Hyperledger Besu, an Ethereum-compatible enterprise blockchain client, as the permissioned ledger for access control and audit logging due to its alignment with the Enterprise Ethereum specification and its native support for fine-grained permissioning under Byzantine fault-tolerant consensus. Unlike other permissioned blockchain platforms that rely on channel-based data isolation and tightly coupled execution models, Besu enables standardized EVM-based smart contracts and seamless integration with service-oriented architectures.

This choice is particularly suitable for WiraChain, where blockchain interactions are intentionally limited to authorization events and immutable audit records rather than high-throughput clinical data processing. In this context, Besu provides a balanced trade-off between audit transparency, cryptographic security, and ecosystem interoperability, while off-chain FHIR services handle time-sensitive clinical workflows and data-intensive operations (30).

The HAPI FHIR framework enables semantic interoperability aligned with the HL7 FHIR standard, ensuring structured clinical data exchange across heterogeneous healthcare systems. FHIR adoption in hybrid architectures has been shown to significantly enhance interoperability and machine-readable data exchange, which is particularly critical in fragmented healthcare environments such as those found in regional clinical networks.

By clearly separating responsibilities—React for interface design, .NET for orchestration, MySQL for transactions, Besu for immutable logging, and FHIR for standardization—the architecture enhances interoperability and data integrity compared with prior monolithic or single-technology stacks. Furthermore, deploying the platform on AWS strengthens security, scalability, and adherence to healthcare data management best practices through managed identity services, encrypted communications, and resilient infrastructure (31).

Notably, backend framework performance benchmarks in peer-reviewed research indicate that compiled frameworks such as ASP.NET Core (C#) demonstrate superior request throughput and lower average response times compared to interpreted Python-based frameworks such as Django and FastAPI in REST API contexts. These performance advantages translate into more efficient request handling, improved scalability under load, and lower server resource utilization—factors that are essential for clinical data systems that must handle high concurrency and low-latency transactions (32).

Figure 3 illustrates the physical architecture of the system, designed according to modern software engineering principles. The modular and decoupled structure enhances reliability, scalability, and maintainability by preserving data integrity and allowing for the independent evolution of components. This design follows SOLID principles and Infrastructure as Code practices. These features are especially beneficial for decentralized applications, blockchain-based electronic health record (EHR) systems, and FHIR-compatible solutions, where interoperability, security, and traceability are crucial. Overall, the proposed architecture serves as a robust and adaptable foundation for advanced clinical applications (33).

The off-chain layer encompasses all processes executed outside the primary blockchain network, serving as the central hub for business operations and data management across services. Its external execution enhances system performance, reduces network load and transaction costs, and maintains data integrity. In the proposed application, this layer employs a multi-tier architecture comprising logical, visual, and data components: the logical layer governs business rules and blockchain coordination, the visual layer manages user interactions, and the data layer ensures secure off-chain storage. This architecture, grounded in clean architecture and loose coupling principles, promotes modularity, scalability, and maintainability, while the clear division of on-chain and off-chain functions supports efficiency and interoperability (34).

The WiraChain blockchain layer underpins the platform's security and auditing framework by ensuring integrity, traceability, and non-repudiation of authorization-related events. Implemented on Hyperledger Besu using the QBFT consensus mechanism, this layer provides deterministic finality, fault tolerance, and strong resistance to tampering, enabling authorization decisions to be recorded as immutable and verifiable evidence (35). The blockchain layer is intentionally scoped to support governance and auditability functions rather than high-frequency clinical data processing.

By recording authorization outcomes on-chain, WiraChain extends conventional role-based access control (RBAC) mechanisms with an immutable and independently verifiable audit layer. Unlike centralized RBAC systems, where access decisions are enforced and logged within a single institutional boundary, the proposed approach enables cross-institutional verification of permission grants and revocations. This design strengthens accountability, provides non-repudiation, and reduces reliance on a single trusted authority, thereby improving security in distributed interoperability scenarios without exposing sensitive clinical data on-chain.

At the core of the on-chain layer, WiraChain records authorization outcomes through dedicated smart contracts that emit audit events indicating whether access to specific clinical resources has been granted, revoked, or overridden. These events do not store personal or clinical data. Instead, only minimal audit metadata is recorded, including pseudonymized identifiers, resource categories, action types, and timestamps. This design ensures that the blockchain functions exclusively as an immutable audit trail for authorization decisions rather than as a repository of protected health information.

From a security engineering perspective, the current implementation prioritizes architectural security properties over exhaustive adversarial evaluation. Formal threat modeling, penetration testing, and third-party smart contract security audits were not conducted as part of this study, as the primary objective was to validate architectural feasibility and interoperability rather than production readiness. Nevertheless, the attack surface of the blockchain layer is intentionally minimized: smart contracts do not store sensitive data, do not perform external contract calls, and expose a limited set of deterministic functions focused solely on permission logging. These design choices reduce common vulnerability vectors and establish a secure baseline suitable for further hardening in future deployments.

Smart contracts are developed in Solidity and deployed using Node.js, TypeScript, and the ethers.js library, following security-by-design and modularity principles. On-chain operations are limited to event emission, optimizing efficiency and minimizing resource consumption. The QBFT consensus mechanism enables low-latency block finalization, while secure key management across validator nodes and indexed blockchain events support reliable correlation between on-chain audit evidence and off-chain clinical records.

Together, these components establish a scalable, interoperable, and auditable infrastructure aligned with healthcare information security requirements. In addition to standard authorization auditing, WiraChain supports exceptional clinical scenarios through a controlled emergency (“break-glass”) access mechanism.

Emergency access can be activated only by predefined clinical roles under exceptional circumstances, such as life-threatening situations where prior patient consent cannot be obtained. Each activation is explicitly marked as an emergency event and immutably recorded on-chain, including the actor role, timestamp, and scope of access. These events are subject to post-incident review by institutional oversight entities, enabling misuse detection and accountability enforcement. Patient notification and organizational response procedures are handled off-chain in accordance with institutional policies and applicable regulations. While the break-glass mechanism does not aim to prevent misuse entirely, it ensures that any emergency access is transparent, traceable, and auditable.

In addition to standard authorization auditing, WiraChain supports exceptional clinical scenarios through a controlled emergency (“break-glass”) access mechanism. Emergency access can be activated only by predefined clinical roles under exceptional circumstances, such as life-threatening situations where prior patient consent cannot be obtained. Each break-glass activation is explicitly marked as an emergency event and immutably recorded on-chain, including the actor role, timestamp, and scope of access. These events are subject to post-incident review by institutional oversight entities, enabling detection of misuse and enforcement of accountability measures. Patient notification procedures and organizational responses are handled off-chain in accordance with institutional policies and applicable regulations. While the break-glass mechanism does not prevent misuse by itself, it ensures that any emergency access is transparent, traceable, and auditable.

This component, developed using the HAPI FHIR framework, implements a RESTful API compliant with the HL7 FHIR standard to enable the creation, validation, and exchange of interoperable clinical resources. It functions as the central integration point for data orchestration across heterogeneous healthcare systems, ensuring semantic consistency, traceability, and data integrity in distributed environments. HAPI FHIR was selected for its maturity, full compliance with FHIR specifications, and seamless integration with Java, facilitating adaptability to local healthcare contexts in alignment with HL7 FHIR R4 and ISO/IEC 27001 information security principles (36).

The implementation adheres to the Peruvian Ministry of Health's interoperability framework established by Ministerial Resolution No. 080-2022/MINSA (37), as well as to Law No. 29733 on personal data protection (38). With respect to regulatory compliance, WiraChain is designed to align with the principles established by this legal framework, as well as internationally recognized data protection regulations such as HIPAA and GDPR. This alignment is achieved through data minimization, off-chain storage of clinical information, patient-controlled authorization mechanisms, and immutable audit logging.

It is important to note that no formal regulatory compliance certification or legal accreditation was pursued within the scope of this research. Such certification processes require institutional deployment, organizational controls, and regulatory audits that exceed the objectives of an academic prototype. Consequently, regulatory compliance is treated as a design objective rather than a certified guarantee.

The persistence architecture employs a dual storage model, combining a structured internal database for operational efficiency with a PostgreSQL database normalized according to FHIR resources, ensuring interoperability and seamless data exchange with external systems.

To illustrate the interaction between the application and various patients, as well as the mechanisms for information exchange, a representative use case was developed based on the approach outlined by Mandarino et al. (39). This case study implements an interoperability solution for a healthcare clinic in Lima, Peru, using the HL7 FHIR standard to integrate diverse clinical systems with a private blockchain network that serves as a distributed ledger. This configuration provides a structured methodology for demonstrating the technical feasibility and data exchange protocols of the proposed model, creating a foundation for subsequent clinical validation. While the simulation is a necessary first step in a controlled environment, we acknowledge that future work must involve pilot deployments in operational healthcare settings to fully assess workflow integration, usability, and regulatory compliance.

To demonstrate the platform's technical functionality, we present a simulated scenario involving Dr. Paul Jones from the Jesús Esperanza Clinic. In this scenario, Dr. Jones must provide emergency medical attention to Nathan Jack, a foreign patient without a local clinical history. Clinical data relevant to the encounter may originate from different sources, including locally registered records or manually entered information when prior digital data are unavailable. These data are incorporated into the platform through institutional clinical workflows and managed according to WiraChain's internal data model. Interoperability mechanisms operate independently of the underlying distributed ledger, allowing data originating from paper-based records or non-DLT interoperability systems to be incorporated without requiring blockchain support at the data source. This design was validated to demonstrate a core architectural principle: when information exchange with external entities is required, selected data are exposed through standardized HL7 FHIR resources. The process begins with a federated query executed through the FHIR API, which retrieves standardized clinical resources from an external server. Each stage of the interaction is recorded immutably on the blockchain network through transactions containing cryptographic hash values, enabling traceability and integrity verification without storing clinical content on-chain. This simulation serves as a proof of concept for the technical workflow, which is a prerequisite for engaging in real-world clinical trials.

To support interoperability among systems at the Jesús Esperanza Clinic using WiraChain, several preparatory steps were undertaken. The platform was deployed to define its purpose, functionalities, and role in interoperability and auditability. Clinical records were registered within the platform's internal data model and, when necessary, mapped to HL7 FHIR representations to enable standardized exchange across institutional boundaries. Authorized users, including patients, clinicians, and administrators, were registered, and training sessions were conducted to familiarize staff with the platform, the HL7 FHIR standard, and blockchain-based auditing mechanisms. These sessions were instrumental in refining the system's interface and procedures; however, we recognize that formal, empirical usability studies and clinical user acceptance testing with healthcare professionals in live environments constitute essential future work to address practical adoption barriers.

For the simulation, the complete application stack was containerized and deployed within an isolated AWS instance. All components operated in a controlled environment to ensure reproducibility and consistency of the initial technical evaluation. The main steps of this testing procedure are described below. This synthetic validation establishes a necessary baseline for functionality, security, and data integrity prior to the significant logistical and regulatory complexities of a clinical pilot study.

The performance evaluation of the Wirachain platform was conducted by analyzing two key metrics: (1) transactions per second and (2) latency. To achieve this, load tests were performed to simulate the operating conditions of a production environment. The aim was to replicate the actual behavior of the system under varying levels of demand in a controlled manner.

These tests are crucial for measuring the platform's processing capacity, identifying potential bottlenecks, and validating its scalability and stability before large-scale deployment. This process ensures optimal performance in real-world operating conditions (24). The experimental setup included a Hyperledger Besu blockchain network utilizing the QBFT consensus mechanism, which was deployed on an Amazon EC2 t3.2xlarge cloud computing instance. To conduct the load tests, a performance script was created using the ethers.js v6 library.

Scripts were designed to measure throughput (Transactions Per Second - TPS) and latency by executing a large number of concurrent transactions that triggered the critical functions of Wirachain smart contracts deployed on the network. This method enables us to obtain specific and relevant performance metrics that reflect the platform's actual operations. Following the methodology proposed by Sharma et al. (41), this work incorporates key metrics for performance analysis: Throughput (TPS) and Average Latency (ms). Throughput indicates the number of transactions completed per second during a given time interval and is calculated using the following formula:

where N is the total number of transactions processed and T denotes the total execution time of the experimental batch (in seconds).

where L_i represents the latency measured for the i-th transaction and N is the total number of transactions in the batch.