Unleashing the Potential of Permissioned Blockchain: Addressing Privacy, Security, and Interoperability Concerns in Healthcare Data Management

Abstract

Blockchain technology leverages a cryptographic system to provide secure and immutable storage of transaction histories within a decentralised framework. While various industries have demonstrated interest in integrating blockchain into their IT systems, concerns regarding accessibility, privacy, performance, and scalability persist. Permissioned blockchain frameworks offer a viable solution for securing confidential records. Extensive research has been conducted to explore the opportunities, challenges, application areas, and performance evaluations of different public and permissioned blockchain platforms. Given the sensitive nature of medical information, healthcare organisations must adhere to various legal obligations, including HIPAA regulations, to protect these data. Although navigating these requirements can be challenging, it is crucial for safeguarding the reputation of healthcare providers, maintaining patient trust, and avoiding legal repercussions. Permissioned blockchains represent decentralised digital ledgers tailored to collaborate among businesses and organisations. Their popularity has increased significantly in recent years, resulting in the availability of several leading options, such as Hyperledger Fabric, Corda, Quorum, and MultiChain. Each of these platforms presents its own set of advantages and disadvantages. Although blockchain technology remains relatively nascent in the permissioned realm, several factors warrant consideration when comparing these platforms. This study will review the existing landscape of blockchain technologies in healthcare applications and identify the research scopes. This research aims to determine how permissioned blockchain technology can effectively fulfil the requirements for managing healthcare data.

1. Introduction

Healthcare data management encompasses the systematic handling, storage, protection, analysis, and use of information derived from diverse sources. Its primary objectives are facilitating informed decision-making, enhancing individual patient care and population health management, supporting clinical research endeavours, and ensuring compliance with regulatory frameworks while preserving patient confidentiality.

The absence of established data management standards could engender significant challenges for the healthcare industry, including misdiagnoses, inappropriate treatments, compromised patient safety, lost research opportunities, and diminished accountability. Despite their critical importance in contemporary healthcare operations, medical data remain susceptible to various security threats. Data from Security Intelligence reveal a startling 250% increase in the number of breaches within the healthcare sector from 2011 to 2021. While the Fortified Health Security 2023 Horizon Report indicated a slight reduction in breaches during 2022, the healthcare industry continues to incur the highest average cost per breach, estimated at approximately USD 10.1 million. A substantial majority of data breaches (78%) are attributed to hacking and IT incidents, with unauthorised access, theft, data loss, and improper data disposal significantly contributing to these vulnerabilities. Notably, these statistics do not inherently imply a lack of adherence to data management guidelines by healthcare organisations and health technology companies. To mitigate these challenges, robust security measures must be implemented. These measures include encryption protocols, access controls, continuous data quality monitoring, regular security audits, comprehensive risk assessments, and formulating thorough incident response plans. Healthcare data originate from many sources and stakeholders, including healthcare facilities, telemedicine platforms, laboratories, pharmacies, patient portals, wearable devices, and public health agencies. Integrating these diverse, multi-format data into a holistic patient profile while maintaining accuracy and context presents a significant challenge. Furthermore, healthcare data are multifaceted, emerging from various sources such as electronic health records (EHRs), medical devices, imaging systems, and wearables, each governed by distinct data standards. This diversity complicates the ability of healthcare providers to analyse and disseminate data cohesively, thereby hindering the development of a comprehensive understanding of a patient’s health. The healthcare sector has undergone transformative changes due to the information technology revolution in the last century. Over recent decades, innovations such as telemedicine, digital hospitals, electronic health records, and mobile health technologies have seen extensive adoption. The rapid advancements in the Internet of Things (IoT) propel healthcare beyond a purely digital paradigm into an era of intelligent healthcare systems. Healthcare data are generated from a variety of sources, such as the following:

• Primary sources: direct observations, interviews, and surveys;
• Secondary sources: online data, such as electronic medical records and research data;
• Wearable tech, smartphones, and apps: user-generated data that can supplement existing clinical data.

Other health data sources include hospital admission forms, prescriptions, disease registries, diagnostic and pathology data, etc.

Moreover, blockchain technologies possess the potential to enhance the preservation and management of healthcare data. Given the unique characteristics of healthcare information, permissioned blockchain—a specialised form of distributed ledger technology—can restrict network access and transaction validation to a predetermined group of authorised entities or participants. Unlike permissionless blockchains such as Bitcoin and Ethereum, which permit unrestricted participation, permissioned blockchains necessitate that users obtain authorisation from network administrators or governing bodies. This restricted access ensures that only trusted parties can uphold the ledger’s integrity, contribute to the consensus process, and validate transactions. Permissioned blockchains offer distinct advantages over their permissionless counterparts, rendering them indispensable in specific applications within the healthcare sector. Moreover, it provides patients control over their data.

In order to fulfil the objectives of our study, a meticulous and methodical approach was employed to identify and initially analyse a significant number of scholarly articles deemed pertinent to our research focus. The contributions of this paper can be summarised as follows:

• It provides a comprehensive review of the current literature (2016–2024) using a systematic approach.
• The presented review involved a detailed examination of some popular permission-based blockchain framework analyses.
• It has identified various challenges and complexities associated with Blockchain adoption for healthcare data.

The remainder of this paper is organised as follows: In Section 2, we outline the research methodology employed in this paper to identify significant publications related to blockchain in healthcare data management. Section 3 provides an overview of blockchain technology. Section 4 illustrates the application of blockchain technologies in the healthcare sector. Section 5 describes related works. Section 6 provides discussions. Section 7 concludes our study, encompassing potential avenues for further research.

2. Research Methodology

This section describes the literature review methodology used for this study. The method follows a structured procedure to define the research topic, perform a literature search, screen the results, extract data from the selected studies, and subsequently analyse and synthesise the findings, either qualitatively or quantitatively. The process involves determining the research questions, identifying appropriate data sources, selecting search techniques, establishing inclusion and exclusion criteria, extracting data, and conducting analysis and synthesis.

2.1. Search Strategy and Data Selection

An extensive electronic search was conducted in reputable academic databases, including IEEE Xplore, Scopus, ACM Digital Library, and Google Scholar, to gather the necessary data for the review papers. The blockchain terminology used in our research queries has been integrated into the areas of healthcare study (see

Table 1. Search terms for the literature selection.

Serial	Search Term
1	(“Blockchain” AND “Healthcare”) OR (“Blockchain” AND “patientcare”)
2	(“Blockchain” AND “Health”) OR (“Blockchain” AND “medical”)
3	(“Blockchain” AND “medicine”) OR (“Blockchain” AND “mhealth”)
4	(“Blockchain” AND “telehealth”) OR (“Blockchain” AND “EHR”)
5	(“Blockchain” AND “EMR”)

). Since our research focuses on blockchain integration in healthcare, the search terms were selected based on that. The search was limited to “Health” and “Blockchain” keywords and their synonyms or related words. Then, we further scrutinised and filtered based on private or permissioned blockchains. In order to retrieve pertinent scholarly publications, Boolean search methodologies employing the logical operators “AND” and “OR” were utilised for specific phrases. Various search terms were deployed throughout this process. Furthermore, a comprehensive analysis of the references within the relevant publications was conducted to identify additional academic sources.

The string-matching process within search terms in digital libraries entailed meticulously examining the titles, abstracts, and keywords associated with the publications. Rigorous filtering and screening procedures were implemented to ascertain the most relevant papers, guided by well-defined inclusion and exclusion criteria.

Table 2. Inclusion criteria for selection of the literature.

IC#	Inclusion Criteria
IC1	A study that is related to the blockchain network
IC2	The search term keywords in Table 1 have an AND operator, so both key terms must be present in the search, whereas the OR operator means that at least one of the key terms should be in the search
IC3	A study published from 2016 to 2024
IC4	A study that has blockchain, blockchain analysis, and healthcare data analysis in the title of the research work

and

Table 3. Exclusion criteria for selection of the literature.

EC#	Exclusion Criteria
EC1	The title does not include critical terms such as “Blockchain”, “Healthcare”, “Patientcare”, “Telehealth”, “Health”, “EMR”, “EHR”, “e-Health”, “Medical”, and “Medicine”.
EC2	Duplicated articles obtained from different databases.
EC3	The abstract is not related to the research area of the literature review.

elucidate the inclusion and exclusion criteria. Since the Google Scholar database was used, some papers were duplicated with other database searches. In addition to similar titles, different papers might exist that also require exclusion. In addition, we searched for healthcare research studies with blockchain terminology; we found some papers purely related to medical science. So, those require exclusion. The entire process can be shown in a flow chart as shown in Figure 1.

2.2. Title-Based Selection

The strategy employed for expeditious article selection used a title-based approach. We excluded papers from our study that do not contain the phrases “blockchain”, “healthcare”, or “patient care” in their titles, as they are irrelevant to our research. The aforementioned action resulted in the cumulative count of papers reaching 2577.

2.2.1. Abstract-Based Selection

The relevance of the 1552 abstracts to our literature review was assessed. At this juncture, the unnecessary abstract articles were disregarded, resulting in the selection of 77 papers.

2.2.2. Full-Paper Review

The comprehensive set of 77 research papers underwent a rigorous filtration process based on predetermined exclusion criteria. Subsequently, we employed Litmaps tools to facilitate an intuitive search for the 19 most relevant and interconnected research papers. (see Figure 2 and

Table 4. List of publications, their contributions, and methodologies.

Ref.	Year	Publication Type	Contributions	Methodology Used
[1]	2024	Journal	Explores blockchain in tracing medicinal supplies for counterfeit detection, analysing IBM’s model for healthcare in developing countries.	Strategic framework for securing medical data; literature review on blockchain in healthcare for EHR management and supply tracking.
[2]	2023	Journal	Evaluates the literature on blockchain’s privacy and security in healthcare from 2017 to 2022, with future research directions.	Discusses blockchain’s role in medical data storage, transactions, and trust-building in decentralised healthcare.
[3]	2018	Journal	Proposes a secure framework for transferring health records, minimising unauthorised access.	Uses Ancile, a blockchain framework with QuorumChain for standard transactions.
[4]	2018	Journal	MedBlock system for efficient EMR access via distributed ledger, addressing security and privacy.	Introduces MedBlock, a blockchain-based system for EMR management challenges.
[5]	2018	Journal	Identifies blockchain interest in healthcare for data sharing and access control.	Systematic review of blockchain research in healthcare, covering background and applications.
[6]	2020	Journal	Identifies blockchain use cases in patient data management and clinical trials.	Scoping review of blockchain applications in health sciences.
[7]	2016	Proceedings	Introduces MedRec, a decentralised EMR management system using blockchain.	MedRec’s modular design integrates with healthcare providers’ storage for interoperability.
[8]	2020	Journal	Synthesises a framework categorising blockchain applications in healthcare.	Systematic literature review on blockchain’s healthcare impact.
[9]	2018	Journal	Proposes a blockchain-based data preservation system for secure medical data storage.	Ensures data verifiability and user privacy in medical data management.
[3]	2018	Journal	Reviews blockchain’s healthcare applications with taxonomy, motivations, and challenges.	Systematic review of blockchain in healthcare.
[10]	2020	Journal	Identifies emerging trends and limitations in healthcare blockchain research.	Systematic review using PRISMA for evaluating blockchain in healthcare.
[11]	2022	Journal	Examines blockchain’s role in decentralised EHR management.	Systematic literature review on blockchain for EHRs.
[12]	2022	Journal	Highlights blockchain’s potential for data accessibility in healthcare.	Not specified.
[13]	2019	Journal	Discusses blockchain’s impact on patient outcomes through data management.	Not specified.
[14]	2019	Journal	Proposes a privacy-preserved blockchain scheme for collaborative medical decisions.	Tests PoF system with MultiChain 2.0 for data privacy.
[15]	2021	Journal	Explores blockchain’s integration with AI and cloud in healthcare.	Systematic review of 50 papers on blockchain in healthcare.
[16]	2018	Journal	Presents FHIRChain, a blockchain-based architecture for FHIR-compliant data sharing.	Uses FHIRChain for secure and scalable clinical data sharing.
[17]	2021	Journal	Examines blockchain’s role in health data, clinical trials, and privacy.	Bibliometric analysis and case studies on telecare and E-health.
[14]	2019	Journal	PoF-based collaborative medical decision system for data confidentiality and collaboration.	Not specified.

).

2.3. Healthcare Data Types

To implement blockchain technology, we must know what types of data are generated or sought in the healthcare sector, such as hospitals/clinics, pathology centres, pharmacies, insurance providers, and regulatory bodies. Healthcare data can be divided into two broad categories—structured and unstructured.

• Structured data: A structured format refers to organising data in a way that allows them to maintain value within specific ranges or adhere to a predefined dictionary. This type of organisation is commonly found in electronic health record (EHR) systems. It includes various components, such as medical codes, medication information, administrative details, vital signs, and laboratory test results. Structured data can be categorised into two primary types: numeric and categorical. Categorical data encompass diagnostic codes, medication classifications, and procedural codes, whereas numeric data consist of quantitative measurements, including respiratory rates, blood pressure readings, pulse oximetry values, and laboratory test outcomes.
• Unstructured Data: A significant portion of electronic health record (EHR) data are unstructured, meaning they are recorded as free text, such as clinical notes and discharge summaries. Clinical notes are documents created for patients in various healthcare settings. Progress notes are a vital subtype of clinical notes that provide information about a patient’s health status during hospitalisation or outpatient care. Unstructured data can include handwritten notes from healthcare providers, such as admission notes, discharge summaries, medical histories, and procedure notes. They also encompass notes that support management tasks like care planning, quality reporting, billing, outpatient visits, emergency department visits, home care, and nursing visits.
• Miscellaneous Data: Semi-structured data as a category is one that the research community has not understood well. Unlike structured data, which reside in fixed fields, semi-structured data do not follow a fixed format. Many healthcare organisations use semi-structured data to record custom and non-standardised information. Examples of semi-structured data in EHR systems include flowsheets or drop-down menus. For instance, “name” with the corresponding “value” for a laboratory test result like “blood pressure” is an example of semi-structured data. More information about semi-structured data can be found in [18,19], where data formats such as JavaScript Object Notation (JSON) and eXtensible Markup Language (XML) are discussed in the EHR context. It can be argued that such data are more similar to structured data because their values are usually restricted, unlike clinical notes. It is important to note that various medical methods, including ultrasound, radiographs, Magnetic Resonance Imaging (MRI), electrocardiogram (ECG), and others, produce unstructured data associated with patients’ medical conditions. These methods have been used independently of structured and textual data for diagnosis in various fields, such as dermatology, radiology, ophthalmology, and pathology [20]. Each method requires specialised pre-processing techniques, data mining knowledge, and understanding of results, making it difficult to study the characteristics of these methods comprehensively. For data such as genomics, transcriptomics, epigenomics, proteomics, metabolomics, and their integration with Electronic Health Record (EHR) data, we recommend referring to [21].

3. Overview of Blockchain Technology

In 1982, Chaum was the first known person to propose a blockchain-like protocol in his PhD thesis [22]. In 1991, Haber and Stornetta described a secured chain of blocks cryptographically [23]. In 1993, Bayer et al. incorporated Merkle trees into the design [24]. In 1998, ‘‘bit gold’’—a decentralised digital currency mechanism, was designed by Szabo [25]. In 2008, Nakamoto introduced Bitcoin, electronic cash with a purely peer-to-peer network [26]. It was also in 2008 that the term blockchain was first introduced as the distributed ledger behind Bitcoin transactions [27]. In 2013, Buterin proposed Ethereum in his whitepaper [28]. In 2014, the development of Ethereum was crowdfunded, and on 30 July 2015, the Ethereum network went live. The emergence of Ethereum implied that blockchain 2.0 was born because, unlike all the various blockchain projects that focused on developing altcoins (other coins similar to Bitcoin), Ethereum enables people to connect through trustless distributed applications on its blockchain. In other words, while Bitcoin was developed as a distributed ledger, Ethereum was developed for distributed data storage plus smart contracts, which are small computer programmes. Ethereum 2.0 upgrades the Ethereum network, which aims to boost its speed, scalability, efficiency, and security. The upgrades have three phases, which were completed between 2020 and 2024.

In 2015, the Linux Foundation announced the Hyperledger project, which is open-source software for blockchains. Hyperledger blockchain frameworks differ from those of Bitcoin and Ethereum to build enterprise blockchain. Under Hyperledger, there are eight block-chain frameworks, including Hyperledger Besu, Hyperledger Fabric, Hyperledger Indy, Hyperledger Sawtooth, Hyperledger Burrow, Hyperledger Iroha, Hyperledger Grid, and Hyperledger Labs; five Hyperledger tools, including Hyperledger Avalon, Hyperledger Cactus, Hyperledger Caliper, Hyperledger Cello, and Hyperledger Explorer; and four libraries, including Hyperledger Aries, Hyperledger Quilt, Hyperledger Transact, and Hyperledger URSA [29]. Figure 3 summarises the history of blockchain. Bitcoin and Ethereum are public blockchains, also called permissionless blockchains, since anyone can participate in their networks. The various Hyperledger blockchain networks are private blockchains, also called permissioned blockchains, since the participants must be verified first before joining the network.

Based on access controls, a blockchain may be classified into two categories: permissionless and permissioned. Figure 4 shows a pictorial representation of the classification of blockchain.

3.1. Permissionless Blockchain

Anyone can access the blockchain network in a permissionless blockchain [30]. The public blockchain is the best example of this type of blockchain.

• Public blockchain: Within a public blockchain [31], the network is open to all, and participants can freely enter and xexit at their discretion. The blockchain’s source code is open; anyone can view transaction blocks. However, transactions are conducted anonymously. Additionally, each participant possesses a duplicate of the blockchain, ensuring that data within it cannot be modified. Any alterations made to the blockchain will alert other nodes on the network.
• Permissioned blockchain: In a permissioned blockchain [32], the network provides access only to authorised nodes assigned specific tasks, ensuring an added layer of security. The identities of each node are carefully maintained, and new nodes can join the network once their identity and roles have been defined. These authorised nodes, known as “permissioned nodes”, are the only ones authorised to perform transactions on the blockchain. Permissioned blockchain can fall into three categories depending on the setup: private, consortium, and hybrid.

3.2. Permissioned Blockchain in Healthcare

Permissioned blockchains are designed to provide regulated access and governance, especially in industries and enterprise settings where data privacy, regulatory compliance, and security are critical. By limiting network participation to authorised entities, permissioned blockchains enhance reliability, security, and regulatory compliance. This controlled access mitigates the risks associated with anonymous involvement and unauthorised access. Additionally, permissioned blockchains often include governance structures that enable stakeholders to establish rules, protocols, and dispute-resolution mechanisms, promoting transparency and accountability within the network. Adopting permissioned blockchains is gaining momentum due to their ability to provide enhanced privacy and confidentiality, which are crucial needs for enterprises and organisations dealing with sensitive information. Permissioned blockchains offer a secure and trusted platform for data sharing and collaboration while protecting the confidentiality of sensitive information by implementing privacy-enhancing features such as encryption, zero-knowledge proofs, and ring signatures. Moreover, permissioned blockchains offer scalability and performance advantages that are particularly beneficial in enterprise environments with high transaction volumes and stringent performance requirements. Unlike permissionless blockchains, which often face scalability challenges due to the open participation of anonymous users, permissioned blockchains can employ efficient consensus mechanisms and network architectures customised to the specific needs of enterprise use cases. By optimising scalability and performance, permissioned blockchains enable organisations to handle large transactions efficiently, support real-time data processing, and meet the demands of mission-critical applications. Furthermore, permissioned blockchains facilitate secure and efficient collaboration among multiple stakeholders, enabling organisations to share data, streamline processes, and reduce friction in business transactions. Consortia and industry groups often leverage permissioned blockchains to establish trusted networks where members can collaborate, share resources, and innovate collectively while maintaining control over their data and operations. Permissioned blockchains foster innovation, accelerate digital transformation, and drive business growth across diverse industries by providing a trusted platform for enterprise collaboration. Additionally, permissioned blockchains offer enterprise cost efficiencies and resource optimisation by streamlining processes, automating workflows, and reducing intermediaries. Smart contracts deployed on permissioned blockchains automate agreement execution, eliminate manual reconciliation processes, and reduce administrative overhead, resulting in cost savings and improved operational efficiency. By leveraging blockchain technology, organisations can optimise resource allocation, reduce transaction costs, and unlock new revenue streams, enhancing their competitive advantage in the marketplace. Finally, permissioned blockchains enhance trust and transparency among participants by providing a shared, immutable ledger of transactions. Enterprises can leverage blockchain technology to track the provenance of goods, verify the authenticity of assets, and ensure data integrity across complex supply chain networks. The transparency provided by permissioned blockchains fosters trust among stakeholders, mitigating fraud and corruption risks and enabling greater visibility in business operations. By promoting trust and transparency, permissioned blockchains empower organisations to build stronger relationships with customers, suppliers, and partners, driving collaboration, innovation, and value creation in the digital economy.

The healthcare sector has explored various blockchain technologies to address data privacy, security, interoperability, and sharing challenges. Several blockchain frameworks are available, but when it comes to enterprise or B2B services, Multichain, Corda, Quorum [33], and Fabric are the most notable options.

Ethereum is a widely recognised public blockchain, while Quorum is a permissioned fork of Ethereum that JP Morgan developed. Quorum has undergone significant changes to the Ethereum framework, including adding permissioned participants, a new consensus algorithm, enhanced transaction privacy, and eliminating transaction fees [34].

Corda, an innovative blockchain solution developed by R3, is a semi-open-source, global, permissioned network that enjoys widespread acceptance in the financial industry. Unlike other blockchain networks, Corda uses a notary pool to achieve consensus, and it does not have any native cryptocurrency, as noted by Brown et al. [35]. The platform’s resemblance to traditional banking and e-commerce systems has contributed to its popularity as a permissioned blockchain.

Multichain is a platform that enables the creation and deployment of private blockchains tailored for specific use cases and controlled by a single organisation. It provides tools for building blockchain applications and managing digital assets. Multichain focuses on scalability, simplicity, and privacy, making it suitable for applications in various industries, including finance, supply chain, and healthcare. With Multichain, organisations can create their blockchain networks, define their rules and permissions, and securely share and manage data and assets within their network [36].

Hyperledger Fabric is a framework for permissioned blockchains that was introduced by the Linux Foundation in collaboration with IBM. It is specifically designed to cater to the needs of consortium business networks. Fabric is an open-source platform with a portable Byzantine fault tolerance protocol. However, other consensus protocols can also be used based on the requirements of the business [37,38].

3.3. Permissioned Blockchain Framework

In this section, we discuss the fundamental components that influence the transaction process of four prominent permissioned blockchains. It is important to note that membership and network services will not be covered in this context.

• Corda:
  Corda is a permissioned distributed network of blockchains that R3 introduced. The network has two main components: the Corda node and the notary pool. The Corda node records the ledger, while the notary pool provides portable consensus to prevent double-spending [35]. Corda is a global network where one member node can participate in multiple closed Corda networks, each with its notary service. Only involved parties maintain the transaction data according to the smart contract. The notary creates a block with consensus to ensure that neither party violates the contract between them [39].
  The notary is a crucial component of Corda and comprises multiple nodes. These nodes interact with each other to arrive at a consensus and make the final decision. Each closed group in the Corda network has its notary service, which may use different consensus algorithms [40]. Figure 5 shows the Corda network with four members and one notary service. The number of members and notaries can be different on different Corda networks.
• Quorum:
  Quorum is a framework designed for permissioned blockchains forked from the Ethereum public blockchain. It consists of three main components: the transaction manager, the Quorum node, and the enclave. The Quorum node is a command-line interface that adds new blocks to the chain and communicates with clients. The transaction manager is another essential component that verifies the private transaction payload and communicates with other transaction managers involved in that particular transaction. Finally, the enclave is the third component to encrypt and decrypt transactions. A Quorum network consists of multiple parties. Every member or interconnected node is known as a party. Each party may have multiple subsidiary nodes or parties to store the blocks of the chain.
  In a blockchain network, the party that initiates the block is called the “maker”. All parties in the network vote on the block. If the block receives a majority of the votes, it is broadcast to all parties in the network. The transaction manager acts as a validator. After a block is broadcasted, the transaction manager of each party checks the hash. The block is stored in its private chain if the hash matches the party’s transaction. If the hash does not match, then the block is rejected.
  In Figure 6, the components of the Quorum party are illustrated. A Quorum party is a member of the network. In a Quorum network, multiple party nodes may be interconnected directly or indirectly. Quorum is a soft fork of Ethereum, which means that each party may store two types of chains: one is public, which stores general Ethereum blocks, and the other is private, which stores private Quorum network blocks.
• Hyperledger Fabric:
  Fabric is a distributed framework used for permissioned blockchains. It allows for the creation of distributed applications using general programming languages such as Node-JS, Java, and Go. Fabric does not have a built-in digital currency and records transactions in an append-only format like other blockchain ledgers. It also maintains a history of transactions. In Fabric’s domain, smart contracts are called chaincodes written in a subset of general programming languages [41].
  The fabric uses endorsers to verify transaction execution and prevent double-spending. The ordering service nodes reach a consensus and create a block of the chain that can be changed according to business requirements. The committing nodes act as record keepers and prepare the ledger.
  Figure 7 illustrates the general architecture of Hyperledger Fabric (excluding membership services). The client, or member app, initiates the transaction, which the endorsers endorse according to the chain codes. After reaching a consensus, the ordering service nodes (OSNs) arrange the transactions and create the block. After consensus, the committers add the block to the chain sent to them by the OSNs.
• Multichain:
  Multichain is a blockchain platform that enables the creation and deployment of private blockchains, primarily aimed at businesses and organisations looking to leverage blockchain technology for various applications. It is built on simplicity, flexibility, and scalability, offering a range of features to facilitate the development of blockchain-based solutions.
  MultiChain’s key feature is its capability to create multiple assets on a single blockchain. This allows organisations to represent various types of assets on the same network, such as currencies, tokens, or certificates. As a result, MultiChain is well suited for a wide range of use cases, including financial transactions, supply chain management, and digital asset management.
  MultiChain solves the problem of monopolisation in private blockchains by restricting mining to a specific set of entities. This algorithm enforces a round-robin schedule, in which permitted miners create blocks in rotation. The mining diversity parameter also defines the proportion of permitted miners needing to collude to undermine the network. Although MultiChain’s security literature is not as extensive as Bitcoin’s, a major threat may arise from a limited number of super-entities, known as Admins, who assign mining rights to other nodes. In the worst-case scenario, if a single Admin is compromised, the reliability of the entire network could be disabled. In Figure 8, a MutiChain voting framework has been illustrated. Unlike MultiChain, Bitcoin has many miners and a global computational power of 40 million TH/s, making a 51% attack very unlikely. Additionally, all these miners have invested money in computational resources and have no interest in undermining Bitcoin’s trust. However, in MultiChain, Admins are just “chosen” entities, and the selection process needs to be carefully monitored. It must involve as many parties as possible to increase the network’s resilience, particularly concerning DDoS attacks. Furthermore, Multichain offers support for atomic exchanges, enabling secure and efficient asset trading between different parties on the blockchain. This feature is essential for applications that require trustless and transparent transactions.
  Overall, MultiChain provides a comprehensive framework for building and deploying private blockchains, making it a valuable tool for businesses looking to harness the power of blockchain technology.

4. Application of Blockchain Technologies in Healthcare Sector

Blockchain technology, with its decentralised and immutable nature, is revolutionising the healthcare industry by providing secure, transparent, and efficient data management; blockchain can address many challenges in healthcare, such as data privacy, interoperability, and supply chain management. This innovative technology can improve patient outcomes, streamline processes, and reduce costs [42].

4.1. Patient-Centric Electronic Health Records

Every country and region grapples with the challenge of data silos within their healthcare systems, leading to a situation where patients and their healthcare providers lack a comprehensive view of medical histories. Research from Johns Hopkins University in 2016 highlighted that the third leading cause of death in the United States stemmed from medical errors, often arising due to inadequately coordinated care [43]. Examples include planned actions not executed as intended or omissions in patient records. A potential remedy to this issue involves establishing a blockchain-based system for medical records, seamlessly integrated with existing electronic medical record software to serve as a unified, comprehensive view of a patient’s records. It is vital to highlight that the actual patient data remain off the blockchain; instead, each new record added to the blockchain, whether it be a physician’s note, a prescription, or a lab result, is transformed into a unique hash function—a distinct string of letters and numbers. These hash functions are exclusive, and their decoding is possible only with the patient’s consent. In this context, any modification to a patient record or the patient’s agreement to share specific medical information is recorded on the blockchain as a transaction. Medical-chain [44] stands out as a prominent example of a company collaborating with healthcare providers to implement blockchain-enabled electronic medical records (EMRs).

4.2. Supply Chain Transparency

Ensuring the authenticity of medical goods is a significant challenge in the healthcare sector, as in various other industries. Employing a blockchain-based system to trace items from the manufacturing stage throughout the entire supply chain gives customers comprehensive visibility and transparency regarding the products they purchase. This issue holds paramount importance for the healthcare industry, particularly in emerging markets where counterfeit prescription medicines contribute to tens of thousands of annual deaths. The significance extends to medical devices, which are rapidly increasing in prevalence with the growing adoption of remote health monitoring, consequently drawing the attention of malicious entities. An exemplary instance is MediLedger, a blockchain protocol that empowers companies involved in the prescription drug supply chain to validate the authenticity of medicines, including crucial details like expiry dates [44].

4.3. Smart Contracts for Insurance and Supply Chain Settlements

By maintaining shared digital contracts on a blockchain ledger among manufacturers, distributors, and healthcare organisations, instead of each participant having their contract versions, significant reductions in disputes over payment chargeback claims for prescription medicines and other goods can be achieved. According to Chronicled, the frequent changes in pricing structures result in over a million chargeback claims annually among these stakeholders, with more than 5% of them being disputed and requiring time-consuming manual resolutions [45]. Similarly, shared smart contracts can streamline the management of medical insurance contracts for patients. Curisium (a healthcare technology platform provider) notes that 10% of the claims are subject to dispute. As with other applications, once these data are digitised and easily accessible, insurance providers can leverage advanced analytics to optimise health outcomes and costs [46].

4.4. Verification and Access Control

Just as the provenance of a medical product can be traced, blockchain technology can also be employed to monitor the professional journey of medical professionals. Trusted medical institutions and healthcare organisations can record the credentials of their staff on the blockchain, offering a streamlined hiring process for healthcare organisations. ProCredEx, based in the US, has successfully created a medical credential verification system utilising the R3 Corda blockchain protocol [47].

4.5. Blockchain Integration in Healthcare

A private and permissioned blockchain solution seems best suited for the healthcare sector. If the blockchain nodes are already known to the network, then such a blockchain is deemed permissioned, such as Hyperledger Fabric, Corda, Multichain, and Quorum. When a network is open to the public, any individual or organisation node can be a member of the network; hence, this type of blockchain is classified as public, such as Ethereum and Bitcoin. Khatri et al. have explored blockchain technology in healthcare [15]. Different core blockchain-based platforms are designed for healthcare data management. These systems generally handle authentication, privacy, and data transparency.

• MedRec—MedRec utilises blockchain technology to give patients secure access to their medical records. This technology saves patients money, time, and effort while preventing the duplication of various installations and services in medical procedures. Patients can also access and share their medical records with anonymous individuals for research purposes [7].
• Medical chain—It is the first healthcare provider to utilise blockchain technology for storing and managing electronic health records, offering a unique telemedicine experience [48].
• Simply Vital Health—This platform utilises blockchain technology, enabling physicians and patients to track and access their medical records and healthcare data, as well as exchange healthcare information [49].
• Gem—The business Gem has collaborated with the “Centers for Disease Control and Prevention” to experiment with the application of blockchain technology to track infectious and communicable diseases, to provide patients with control and access to their health information as well as genome information through blockchain technology [50].
• Nano Vision—Nano Vision blends the potential of blockchain technology with artificial intelligence (AI) to collect molecular data on Nano-input tokens to blend the creativity and transformation in the medical field with existing data silos and incompatible recording systems. AI then examines the data to recognise trends and patterns, analysing the networks and links leading to medical revolutions and inventions [50].
• BurstIQ—The BurstIQ platform assists healthcare firms in managing vast patient data safely and efficiently. Blockchain technology enables data to be stored, sold, shared, or licensed while strictly observing the HIPAA (Health Insurance Portability and Accountability Act) rules [51].

5. Related Works

In the past, a significant number of studies has been conducted on blockchain implementation in modern business sectors. Unlike other sectors, healthcare has specific requirements to ensure patient consent and privacy and to preserve data. Since multiple stakeholders are involved here, interoperability is the biggest challenge. In addition to this, data privacy and integrity is also a major concern. Our research area has been narrowed down to only permission blockchain rather than any public blockchain integration in healthcare. Based on our previous search criteria, we have only selected 19 top studies that are the most relevant and highly co-related. In 2016, Azaria et al. [7] proposed MedRec, a novel, decentralised record management system to handle EMRs, using blockchain technology and incentivising medical stakeholders to participate in the network as blockchain “miners”, enabling the emergence of data economics. This provided patients with immutable logs and easy access to their medical information across various providers and treatment sites, enhancing patient agency over their data. The system manages critical aspects such as authentication, confidentiality, accountability, and data sharing, which are essential for handling sensitive medical information. It incentivises medical stakeholders to participate in the network through mining rewards, fostering data economics and empowering researchers to access aggregate, anonymised data. In 2018, Dagher et al. [3] proposed a privacy-preserving blockchain framework where patients would have final control of electronic health records. The paper employs a blockchain framework named Ancile, which utilises the QuorumChain consensus algorithm for standard blockchain transactions. It incorporates four distinct actions: standard transactions, internal transactions data sent to smart contracts, and private transactions to enhance data integrity and privacy. The framework ensures secure access control by validating the identities of providers and third parties before registration, thus controlling participation in the permissioned blockchain. The research was focused on similar types of healthcare provided. Interoperability with different healthcare providers was still not identified. Healthcare data could be in static and as well as dynamic form. Several researchers have worked on this type of data. In 2018, Li et al. [9] proposed a novel blockchain-based data preservation system (DPS) for medical data that uses the blockchain framework to provide a reliable storage solution to ensure the primitiveness and verifiability of stored data while preserving user privacy. The proposed system ensures the primitiveness and verifiability of stored medical data while maintaining user privacy through advanced cryptographic algorithms. A prototype of the DPS is implemented on the Ethereum blockchain platform, and performance evaluation results are provided to demonstrate the system’s effectiveness and efficiency. In 2018, Fan et al. [4] introduced MedBlock, a blockchain-based information management system designed to address the challenges of electronic medical record (EMR) sharing and management. It provides a solution for constructing summarised EMRs from multiple hospital databases while ensuring security and privacy. Still, interoperability is a major concern. That is why they proposed eveloping standardised data management and sharing policies across different hospitals, which could be explored to improve the interoperability of EMRs. In 2018, Holbl et al. [5] conducted a systematic review of blockchain technology applications in healthcare, revealing its potential for enhancing patient-centric approaches and improving electronic healthcare records (EHRs). It provides a bibliometric overview and analyses gathered data properties, contributing to a better understanding of the current state of blockchain research in healthcare. Hussein et al., [13,17] employed a systematic review methodology to analyse the research landscape of blockchain technology in healthcare applications. It contributed to the literature by mapping the research landscape and identifying gaps, offering opportunities for further development of decentralised healthcare applications. This research did not focus much on blockchain integration into a specific healthcare setup. Yang et al. [14] propose a privacy-preserved blockchain scheme, proof-of-familiarity (PoF), for collaborative medical decision-making. This scheme addresses the limitations of existing healthcare collaboration methods. A prototype of the PoF system was tested using the MultiChain 2.0 framework, demonstrating superiority over existing schemes in preserving personal data privacy and improving patient-centric outcomes. Anton et al. provided a comprehensive scoping review of blockchain technology’s healthcare and health sciences applications. Overall, the paper emphasises blockchain’s transformative potential in improving healthcare delivery and outcomes. Tandon et al. [8] suggested that future research can facilitate the widespread deployment of blockchain applications to address critical issues related to medical diagnostics, legal compliance, fraud prevention, and patient care in cases of remote monitoring or emergencies. This research suggested integrating blockchain with emerging technologies like AI and IoT to enhance healthcare delivery and outcomes. Chukwu et al. [10] presented a bibliometric analysis of 143 research articles detailing their functional distribution and technical aspects. This research employed a systematic review methodology, leveraging the PRISMA framework to guide searching and evaluating the literature on blockchain applications in healthcare. The study highlights the necessity for further exploration of blockchain architectures beyond Hyperledger and Ethereum, as most prototypes followed similar structures. Hussien et al. [17] highlighted the motivations for employing blockchain technology in the healthcare industry. They discussed potential future challenges such as scalability and storage capacity, blockchain size, universal interoperability, and standardisation. The paper identifies trends in adopting blockchain solutions, emphasising the growing interest among healthcare stakeholders in leveraging this technology for improved operational efficiency. Additionally, the paper notes the absence of frameworks that can guide the adoption of blockchain technology in healthcare, indicating a need for structured approaches. Khatri et al. [15] identify the potential for integrating blockchain with technologies such as artificial intelligence and cloud-based solutions, highlighting innovative applications in healthcare. This research includes a descriptive analysis that provides statistical insights into the strategies of the reviewed papers, focusing on the types of blockchain systems proposed. Gul et al. propose a four-layer system consisting of IoT, fog, blockchain, and cloud layers. The system utilises IoT devices to collect data, fog computing to analyse data, and blockchain technology to ensure data privacy and security [52].

6. Discussions

Consensus is a crucial aspect of any blockchain, regardless of whether it is permissioned. Various frameworks implement different consensus protocols. In this regard, we have compiled a list of consensus mechanisms used in other frameworks and discussed the plug-and-play capability of consensus to determine the leading contender in the race. Since the workings of blockchain heavily depend on consensus, if consensus fails, blockchain fails, too. Different industries may require different consensuses, so having a range of consensus mechanisms is essential. Modularity is used to assess portability and predict future enhancements of a product. The transaction rate of a system determines its speed, which, in turn, indicates the system’s throughput. Different solutions have different transaction rates, which define their throughput. Another factor that sets the systems apart is their currency support. Various solutions support different cryptocurrencies, while some have no cryptocurrency module. Adaptability is a crucial consideration as it defines the public acceptance of the system. In the recent past, governments and financial institutions were not open to blockchain technology due to gambling and, in some regions, the significant energy consumption associated with proof of work. However, in private blockchains, all network members’ identities are known, and lightweight consensus protocols are used, making adaptability higher than in public blockchains.

The choice of programming language can play a significant role in the early stages of developing a framework. If the framework only supports a specific or complex language, application developers may require special training, and the maturity of that language may be uncertain. On the other hand, if the framework supports a general programming language, the product will be more adaptable and widely accepted. Privacy is an essential aspect that was missing in the initial public blockchains. In this regard, we have discussed each product’s private features and extracted their results. With its controlled access and permissioned network, private blockchain technology offers significant potential for transforming healthcare. Providing a secure and transparent platform for data sharing and management addresses critical challenges such as privacy, interoperability, and supply chain transparency. However, implementing private blockchain in healthcare is not without its complexities.

6.1. Limitations

While blockchain technology offers immense potential for revolutionising the healthcare sector, it is not without its limitations [53]:

• Scalability: Blockchain networks can become congested, especially when dealing with large volumes of data. This can lead to slower transaction times and increased costs.
  Scaling solutions like sharding and layer-2 solutions are still under development and might not be fully mature for large-scale healthcare applications.
• Complexity: Blockchain technology is complex, requiring specialised knowledge to implement and maintain. This can be a barrier for healthcare organisations that may not have the necessary expertise. The technical challenges associated with integrating blockchain into existing healthcare systems can be significant.
• Interoperability: Different healthcare systems and organisations often use different data standards and formats. Ensuring seamless interoperability between blockchain networks and legacy systems can be complex. Establishing standardised protocols and data exchange formats is crucial to overcome this challenge.
• Regulatory Hurdles: The regulatory landscape for blockchain technology is still evolving. Healthcare is a highly regulated industry, and implementing blockchain solutions may require navigating complex regulatory requirements. Compliance with data privacy regulations like HIPAA is essential, and it is critical to ensure that blockchain solutions adhere to these regulations.
• Cost: The initial costs of implementing a blockchain solution can be significant, especially for smaller healthcare organisations. Ongoing maintenance and operational costs should also be considered.

6.2. Future Scope

The implementation of blockchain in the healthcare sector is a complex endeavour fraught with several challenges. One of the most significant hurdles is the sheer volume of data generated within the healthcare system. Blockchain’s inherent scalability and data storage limitations could prove insufficient for handling vast medical records, imaging data, and genomic information. Additionally, the decentralised nature of blockchain can lead to interoperability issues, as different healthcare providers and institutions may use incompatible systems and standards. Ensuring seamless data exchange and integration across diverse blockchain networks is a crucial challenge that requires careful planning and standardisation efforts. Furthermore, the sensitive nature of healthcare data necessitates robust security measures to protect patient privacy and confidentiality. While blockchain offers enhanced security features, it is not entirely immune to cyber threats. Strong security protocols, including encryption and access controls, mitigate risks and safeguard patient information. Finally, regulatory compliance is a major concern in the healthcare industry. Integrating blockchain technology into existing regulatory frameworks, such as HIPAA, requires careful consideration and potential modifications to ensure data privacy and adherence to security standards.

To overcome these challenges, several strategies can be adopted. Scaling solutions, such as sharding and layer-2 protocols, can help alleviate the scalability limitations of blockchain. Developing standardised data formats and protocols can improve interoperability between different blockchain networks. Robust security measures, including encryption, access controls, and regular security audits, can safeguard patient data. Collaborating with regulatory bodies to develop clear guidelines and standards for blockchain implementation in healthcare can facilitate compliance and adoption. Additionally, fostering a culture of innovation and collaboration among healthcare providers, technology companies, and policymakers can accelerate the development and adoption of blockchain solutions. By addressing these challenges and implementing appropriate strategies, the healthcare sector can unlock the full potential of blockchain technology to improve patient care, streamline processes, and enhance data security.

Despite these limitations, the future scope of blockchain in healthcare is promising. A collaborative approach involving healthcare providers, technology experts, and policymakers is essential to overcome these challenges. This collaboration can help establish clear guidelines and standards for implementing private blockchain solutions, ensuring interoperability and data privacy. Moreover, fostering open-source development and community engagement can promote innovation and address technical complexities. By addressing these concerns and embracing a collaborative approach, private blockchain technology can unlock its full potential to revolutionise healthcare, improving patient outcomes and increasing efficiency. Blockchain technology is widely adopted in the business and financial sectors and is considered a game-changer. However, many companies find it difficult to decide which framework to use. Although the final decision depends on the nature of the business, some general criteria can help them make an informed choice. Quorum is a framework with limited adaptability due to its lack of modularity, language support, and limited cryptocurrency support. In contrast, Corda has some advantages over Quorum, such as its new hardware security module, modular consensus, and support for more programming languages [3]. After analysing the available options, Hyperledger Fabric appears to be the most adaptable framework. It offers a wide range of consensus algorithms and modular and pluggable consensus support and can be tailored to meet the needs of various industries. Fabric supports popular programming languages, offers higher transaction rates, and can handle fiat money and cryptocurrency, making it a good option for crypto and non-crypto groups. However, there is still room for improvement in security, privacy, and transaction rates.

7. Conclusions

Integrating private blockchain technology into healthcare requires a multifaceted approach. First, it is crucial to understand the specific use case and desired outcomes clearly. This involves identifying the main points and inefficiencies within the current system and determining how blockchain can address them. Next, a suitable blockchain platform must be selected, considering scalability, security, and interoperability factors. Popular options include Hyperledger Fabric, Corda, and Quorum. While permissionless blockchains offer the benefits of decentralisation and transparency, they may not be the best fit for all healthcare use cases. Permissioned blockchains, on the other hand, provide a more secure, efficient, and compliant solution for managing sensitive healthcare data. Finally, a phased approach to implementation is recommended, starting with smaller-scale pilots to test the technology and identify potential challenges. As the technology matures and confidence grows, larger-scale deployments can be undertaken. Collaboration between healthcare providers, technology experts, and policymakers is vital to overcome challenges and ensure successful integration. By carefully planning and executing the integration process, private blockchain can revolutionise healthcare, improving patient outcomes, enhancing data security, and streamlining operations.