# Systematic Assessment of the Interoperability Requirements and Challenges of Secure Blockchain-Based Electronic Health Records

Authors: Faheem Ahmad Reegu; Hafiza Abas; Zaid Hakami; Sanatan Tiwari; Rudzidatul Akmam; Iskandar Muda; Hashem Ali Almashqbeh; Rituraj Jain
Journal: Security and Communication Networks
 (2022)

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## Abstract

A peer-to-peer (P2P) decentralized information-sharing network is used to share data and maintain security, privacy, and integrity standards called blockchain. In this case, information sharing and updating require regular simplification. The presented systematic review mainly focuses on the interoperability of electronic health records (EHRs) using blockchain. Correspondingly, 18 blockchain-based solutions were selected to address the interoperability challenges of EHRs. The limitation of solutions includes reliability, privacy, integrity, sharing, and standards. This systematic review contains six phase’s research question, research phase, article selection, abstract-based keyword, data extraction, and progress tracking. Various Web resources such as Google Scholar, Web of Science, and IEEE are used to extract the relevant manuscripts. Primarily, 18 articles were selected to present the interoperable requirements of EHRs using blockchain, standards of blockchain-based EHRs, and solutions for interoperability of EHRs using blockchain. The conducted study explains the best available interoperable blockchain-based EHR standards, implementations, applications, and challenges.


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## Body

## 1. Introduction

Blockchain is a decentralized, fast, secure, and private technology used to exchange information. Blockchain technology can transform the traditional healthcare system by maintaining patient data privacy and security [1]. Blockchain has the power to change the way patients’ electronic health records are transferred and stored by providing safer ways for medical information transfer in the healthcare industry and securing it via a randomized peer-to-peer network [2, 3]. The implementation of technology makes electronic health records (EHRs) robust and secure [4]. Blockchain technology has the potential to improve health care by putting the individual at the center of the health system and promote health data security, transparency, and interoperability. By making electronic health records (EHRs) more efficient and secure, this technology might create a new paradigm for interoperability (HIE) [5, 6]. The EHR system contains the sensitive information of patients, including diagnostics and treatment. The patient data are an asset for the healthcare system. The collection and distribution of healthcare data are essential sources to analyze the healthcare system’s ability to provide healthcare services [7]. EHR includes critical and very sensitive private information for medical diagnosis and treatment. These databases are a valuable source of patient information. The sharing of healthcare data is an essential step in making the national healthcare intelligent and improving service quality [8, 9]. A structural and well-formatted patient health data are maintained and stored at various hospitals, clinics, and the government, and healthcare department is an EHR [10].Interoperability in an EHR plays a key role, and it refers to the ease with which medical records and healthcare information may be shared from one provider or system to another. While healthcare systems can communicate in a variety of ways, the EHR is widely recognized as one of the simplest and most secure alternatives that do not result in data blockage. By concentrating on EHR interoperability and developing ways to improve it, healthcare systems may smooth out frequent communication channels, increase overall patient contentment, and even reduce common healthcare expenses. An electronic health record (EHR) is a digitally recorded structure of a patient’s health data that is produced and managed over the course of the patient’s life. It can often be stored and provided by various hospitals and clinics, including health professionals [11, 12]. The semantic interpretability concept of EHR [13] has several challenges. Security is the biggest challenge, and electronic healthcare systems are the primary prey of cyberattacks. According to research, one-third of all cyberattack victims were healthcare systems [14]. Blockchain, which supports a sharing and trust mechanism, might be a future option for data sharing, allowing for collective healthcare decision in telehealth and precision medicine [15, 16]. Ransomware 88% of attack victims were healthcare systems. Data of 80 million people are breached during the attack of 4 February 2015 called anthem breach attack. Another challenge is the size of the EHR database, which is increasing rapidly. The patient data [17] include patient information and X-rays, and computed tomography, which has a large size and requires ample storage space. In 2015, an average healthcare system had storage space of 665 terabytes, which increased to 25,000 petabytes in 2020. The main occupants of storage space are medical images in the unstructured form [18]. Another challenge is the heterogeneity of healthcare systems. Various health service providers used their database management system, different system architecture, and data infrastructures [19]. Data integrity and standardization are becoming challenging and prominent among cross-health service providers. The heterogeneity of health service providers makes it challenging to share precise and standardized data for useful applications. The study covers the following:(i)
Importance of interoperability of EHR using blockchain technology(ii)
Challenges of implementing blockchain technology in EHR systems(iii)
The requirement of an interoperable blockchain-based system(iv)
A summary of interoperable EHR requirements, problems, and solutionsThe article has six sections. Section2 elaborates on the relevant work on blockchain and its usage in the healthcare system. Section 3 enlightens the research methodology and step adopted for this systematic review followed by Section 4 that presents research question-based results. Section 5 presents requirements, standards, and solution. The article conclusion is presented in Section 6 followed by future directions.


## 2. Related Work

### 2.1. Blockchain

A peer-to-peer (P2P) ledger-based distributed technology used for Web-based information sharing is called blockchain and was initially invented for the financial sector for transactions by skipping the role of arbitrator. It is the same as the mediator in government and private organizations who play a trusted third party (TTP) to receive and process transactions. TTP is not valid and trustworthy because it can be malfunctioning, or a security breach can affect the whole transaction system [20]. The extensive use of electronic health records (EHRs) improves the efficiency and adaptability of medical services. It has the potential to dramatically improve the convenience, intelligence, and accuracy of public healthcare treatment, particularly when combined with cloud storage and mobile apps. Because of its centralized management, EHRs are more vulnerable to centralized assault, purposeful manipulation, and single-point failure. It suggests that protecting patient privacy and other sensitive data will become more difficult, leading to more frequent conflicts between doctors and patients [21, 22]. Technically, blockchain is a decentralized database presented over a P2P network. A typical blockchain contains nodes, contracts, and blocks. The information is stored on a block, and the nodes are the point of connection between the blockchain members. In the blockchain environment, every node contains a copy of local data called a block. When the nodes agree on a contract, the transaction is performed and has validity [23].


### 2.2. Use of Blockchain in Electronic Health Records (EHRs)

Blockchain-based application robustness has provided decent support in the medical industry and medical support systems. Various applications are presented in the literature review for maintaining EHRs by taking into consideration the factor interoperability. Interoperability of EHR enables the health service providers to update a patient’s record over the synchronized blockchain network [24]. The EHR using blockchain is a new era system that monitors patient health and records patients’ treatments, surgeries, and therapies’ schedule.Interoperable EHRs simplify the insurance system by processing the health insurance claims and updating the payment system authentications. Blockchain in EHRs enables researchers and biomedical scientists to utilize the health data to estimate statistical analysis and create robust diagnostic applications and medicines. The importance of blockchain is presented using research reviews, applications, and unique security solutions for problems.Interoperability, scalability, and cross-platform implementation are challenges in the blockchain-based application in the area of health care. A distributed healthcare system that removes the central mediator creates a serious abrupt in the standard healthcare systems [25].


## 2.1. Blockchain

A peer-to-peer (P2P) ledger-based distributed technology used for Web-based information sharing is called blockchain and was initially invented for the financial sector for transactions by skipping the role of arbitrator. It is the same as the mediator in government and private organizations who play a trusted third party (TTP) to receive and process transactions. TTP is not valid and trustworthy because it can be malfunctioning, or a security breach can affect the whole transaction system [20]. The extensive use of electronic health records (EHRs) improves the efficiency and adaptability of medical services. It has the potential to dramatically improve the convenience, intelligence, and accuracy of public healthcare treatment, particularly when combined with cloud storage and mobile apps. Because of its centralized management, EHRs are more vulnerable to centralized assault, purposeful manipulation, and single-point failure. It suggests that protecting patient privacy and other sensitive data will become more difficult, leading to more frequent conflicts between doctors and patients [21, 22]. Technically, blockchain is a decentralized database presented over a P2P network. A typical blockchain contains nodes, contracts, and blocks. The information is stored on a block, and the nodes are the point of connection between the blockchain members. In the blockchain environment, every node contains a copy of local data called a block. When the nodes agree on a contract, the transaction is performed and has validity [23].


## 2.2. Use of Blockchain in Electronic Health Records (EHRs)

Blockchain-based application robustness has provided decent support in the medical industry and medical support systems. Various applications are presented in the literature review for maintaining EHRs by taking into consideration the factor interoperability. Interoperability of EHR enables the health service providers to update a patient’s record over the synchronized blockchain network [24]. The EHR using blockchain is a new era system that monitors patient health and records patients’ treatments, surgeries, and therapies’ schedule.Interoperable EHRs simplify the insurance system by processing the health insurance claims and updating the payment system authentications. Blockchain in EHRs enables researchers and biomedical scientists to utilize the health data to estimate statistical analysis and create robust diagnostic applications and medicines. The importance of blockchain is presented using research reviews, applications, and unique security solutions for problems.Interoperability, scalability, and cross-platform implementation are challenges in the blockchain-based application in the area of health care. A distributed healthcare system that removes the central mediator creates a serious abrupt in the standard healthcare systems [25].


## 3. Research Methodology

The systematic research contains six primary tasks such as (1) research question, (2) research steps, (3) suitable article selection, (4) keywords, (5) data extraction, and (6) mapping. A research question is the most significant part of all research procedures before carrying out any research. The research question is the primary tool to determine the blockchain interoperability challenges in EHRs. Related articles need to be reviewed and the interoperability challenges and their possible solutions are found. Several applications of blockchain have been presented, but these are in prototype form. Numerous challenges are persisting in the real world while implementing blockchain applications. Localization of challenges can be performed by conducting studies on relevant manuscripts. The recognition of reliable solutions for specific problems is very critical. Studying relevant articles can lead to the identification of future directions and research gaps.Mapping techniques summarize and categorize the presented solution by researchers to solve specific EHR system interoperability problems. The research question depicts the blockchain base solution for EHRs and future direction to improve blockchains’ applications for maximum performance. Several developments have been presented in the literature, which clearly defines the solution of problems. Clarity of explanations and direction makes it reliable to use blockchain in healthcare systems efficiently. Reliable findings require the implementation of various methods such as search planning, inclusion, and exclusion standard. Keyword and key term-based methods are used to search and extract EHR interoperability-related research articles to identify the challenges and solutions. Google scholar is used to search key terms such as “blockchain,” “healthcare,” and “interoperability of EHRs,” followed by downloading articles from start to latest reports. The items mentioned above are sourced from IEEE, SCOPUS, ACM, journals, and conferences.The research question related to the problem is composed, and research is conducted to find suitable solutions related to challenges systematically. A total of 98 articles were excluded because of the focus on “blockchain” and does not include the “blockchain in health care.” The 18 standard research papers related to blockchain in EHRs with interoperability were selected for data derivation. The inclusion and exclusion criterian are presented in Table 1.Table 1
Inclusion and exclusion criteria.
CriteriaDescriptionInclusionArticles published after 2021Presenting a systematic review of healthcare systems and blockchainIntroduction, conclusion, and abstract are relevant to EHRs and blockchainThe article addressed the blockchain-based EHR challengesEHR implementations and utilizationExclusionNot cited in EHR-related articlesArticles published from 2017 to 2021Articles presentation at several sourcesThe title does not include health care, blockchain, and interoperabilityThe selected articles were scrutinized based on citations using the available database. Citation of relevant research article citation for once is critical. According to interoperability, the article selection was performed based on the maximum number of citations related to the systematic review of EHRs. The selection of the most relevant articles is illustrated in Figure1 in the form of a flow chart.Figure 1
Article’s selection criterion flow chart for systematic review.Figure1 is the flow chart representing the functioning of electronic database. The selected articles are scrutinized and then reviewed. This will provide safer ways for medical information transfer in the healthcare industry and securing it via a randomized peer-to-peer network. In general, all research articles present their keywords after the abstract of the manuscript. Related keywords to this systematic review are blockchain, interoperability, and EHRs.


### 3.1. Data Derivation and Mapping

Selected vital terms and keywords were used to search relevant manuscripts for systematic review, and quotes were compiled from related articles. The mapping of challenges and their possible solutions is extracted and formatted. A systematic method was adopted to highlight specific challenges related to the interoperability of EHRs and their possible solutions. The mapped solution and challenges are discussed in Results. The mapped requirements and standards are elaborated in Table2. The selection of described standards and requirements from 18 selected articles was performed using the ATLAS.ti tool. The discussed tool is also used for keyword searching and the extraction of relevant articles and related information for the systematic literature review. The mapping techniques proved to be more efficient to screen out the most specific research question, requirements of interoperability, standards, challenges, and most appropriate interoperability of blockchain-based EHRs.Table 2
Requirements and standards.
Ref.StandardRequirements[26]FHIRInformation exchange[27]HL7Cross-plate implementation[28]HITECHTransformation[29]PHRInformation sharing using cross-plate APIs[30]Open EHRStandard validation[31]DICOMSecurity[32]SNOMED CTInteroperability and consistency[33]CEN/ISO EN13606Privacy and security[34]HIPAAPrivacy and consistency


## 3.1. Data Derivation and Mapping

Selected vital terms and keywords were used to search relevant manuscripts for systematic review, and quotes were compiled from related articles. The mapping of challenges and their possible solutions is extracted and formatted. A systematic method was adopted to highlight specific challenges related to the interoperability of EHRs and their possible solutions. The mapped solution and challenges are discussed in Results. The mapped requirements and standards are elaborated in Table2. The selection of described standards and requirements from 18 selected articles was performed using the ATLAS.ti tool. The discussed tool is also used for keyword searching and the extraction of relevant articles and related information for the systematic literature review. The mapping techniques proved to be more efficient to screen out the most specific research question, requirements of interoperability, standards, challenges, and most appropriate interoperability of blockchain-based EHRs.Table 2
Requirements and standards.
Ref.StandardRequirements[26]FHIRInformation exchange[27]HL7Cross-plate implementation[28]HITECHTransformation[29]PHRInformation sharing using cross-plate APIs[30]Open EHRStandard validation[31]DICOMSecurity[32]SNOMED CTInteroperability and consistency[33]CEN/ISO EN13606Privacy and security[34]HIPAAPrivacy and consistency


## 4. Bibliometric Analysis

Advancements in data collection and bibliometric analysis are playing vital role in screening out the specific and problem-oriented research articles. Several tools are being utilized in the scientific research to study and select the most relevant research. In this systematic literature review (SLR), VoSviewer tool is implemented to find and analyze the cooccurrence of citations, cooccurrence of authors, and key terms.VoSviewer tools were utilized in this SLR to analyze the cooccurrence of citation and references. The presented network draws a network of citation of research articles based on their references. The cooccurrence of co-citation is presented in Figure2.Figure 2
Reference-based cooccurrence of citations between articles.Cooccurrence of terms and keyword is presented in Figure3. The selected keywords such as healthcare, blockchain, and EHR are utilized to search the related articles. The related articles are then scrutinized based on their relevant content to the SLR. The searched 116 articles were reduced to 18 by the implementation of selection criteria of research questions and requirements. The most occurred keyword during search of relevant articles is healthcare, health information, electronic record, electronic health record, blockchain, data sharing, medical research, health insurance, health information, and EHR connections.Figure 3
Cooccurrence of keywords and terms.The bibliometric analysis also includes the authors of specific country working together or the countries working on specific problem. In this SLR, the VOSviewer is used to create the network of authors and countries working on specific domain of research. The network of such countries is presented in Figure4.Figure 4
Network of countries working on a specific research area.


## 5. Results and Discussion

The results of the systematic review are presented in this section. In the following search strategy, 116 research articles were extracted from various sources. The first selection method removes the duplicate records, and we have a total of 97 articles selected. The removed articles were not related to the interoperability of EHRs and blockchain. The selected articles were scrutinized further for refinement of the selection process. Exclusion criteria were implemented, and 45 articles were removed from 97 articles. During the screening process, the removed articles did not have the full text and could not qualify in the meta-analysis. The remaining 52 articles were accessed for eligibility of selection for systematic review. During the eligibility selection, 34 unrelated articles were removed from the list of selected articles. The remaining 18 articles possess the selection criteria and meet all the requirements for the systematic review of blockchain-based interoperable EHRs.The selected articles are utilized to find the challenges and requirements of interoperable blockchain-based EHRs. The challenges, solutions, and standards of blockchain-based interoperable EHRs are divided into three research questions for the systematic review. The research questions are as follows:Q1. What are the interoperable requirements of blockchain-based EHRs?Q2. What are the blockchain-based interoperable standards for EHRs?Q3. What is the best approach for BC-based EHR in solving this interoperability issue?The research questions are discussed as follows:Q1. What are the interoperable requirements of blockchain-based EHRs?According to the study for this systematic literature review, interoperable requirements of blockchain-based EHRs are categorized into three levels. The levels of interoperable requirements include semantic, technological, and organizational or legal requirements. The semantic requirements illustrate the standard databases, information collection, and exchange of information in this study. The technological requirements include protocols, standards, cross-platform information sharing, and management. Legal and organizational interoperable requirements of blockchain-based EHRs consider the business model and cooperation among different governmental and private health organizations to efficiently provide healthcare services by considering the privacy and security of health information.Blobel et al. [35] presented a semantic model of requirements for interoperable blockchain-based EHR. The presented requirement set contains a vocabulary of protocols for efficient messages and health information transmission. The method implementation at the organizational level requires a good business model coupled knowledge-sharing system. Data standard [29] adaptation is required for data integrity to provide healthcare information sharing robustly. The standard usage makes the blockchain-based EHRs helpful in health insurance claims with adequate information. Data mapping standards [36] are required to make the data sharing among various shareholders seamless. Logical models and programming language components are helpful to reduce the pressure on the federal institutions for data manipulation for health service providers. Blockchain-based systems [37] require semantic consistency. Consistency requires coding standard implementation that can improve the security of EHR. Beštek et al. [36] presented blockchain-based EHR requirement list, including robust data acquisition of data, efficient sharing mechanism among EHRs, and medical scientists to improve healthcare robust and management. EHR blockchain compliance[38] requires sharing formatted and encrypted messages between different systems and decrypting messages according to various stakeholders, which can be achieved by specifying the message standards, allowed values, and technical database according to their predefined rules. The described integrity levels of privacy and security can be achieved by increasing cooperation between vendors, industry, scientists, and health service providing institutes. Information exchange between patients and health service providers requires a set of protocols and standards to ensure data privacy and security. Data integrity and privacy using blockchain created a secure insurance and incentive system at government and private health service providing institutions. EHRs require seamless data transmission to achieve the interoperability using blockchain. The information sharing required an efficient model to transmit health information between different information processing systems. The information sharing among different systems and organizations requires legal frameworks to achieve information integrity [39, 40].The requirements of interoperable requirements of blockchain-based EHRs are described in Table2. The researchers presented different interoperable requirements and application methods for semantic definitions. The semantic requirements of interoperable systems are as follows:(i)
Standard method and protocols for information sharing(ii)
Unambiguous database integrity(iii)
Standard data dictionary and message protocols(iv)
Standards for data acquisitions and sharingThe technological requirements of interoperable blockchain-based EHRs extracted from the study are as follows:(i)
Comparability protocols for plug-and-play services(ii)
Allowed data elements and formats(iii)
Coding standards for robust data creations and transmission(iv)
Secure data transmission protocolsThe organizational and legal requirements of interoperable blockchain-based EHRs extracted from the study are as follows:(i)
Cooperation between EHR vendors and health service providers(ii)
Business models for information sharing between EHRs and industry vendors(iii)
Professional to maintain secure data and information sharing(iv)
Insurance and incentive issue information availabilityQ2. What are the blockchain-based interoperable standard for EHRs?The interoperable stands for blockchain-based EHR application are discussed in Table3. The researchers presented different standards for information sharing, securing, and interoperability of EHRs. The various standards adopted better implementation of blockchain-based interoperable solutions for health service providers.The standard classification performed on better quality, workflow, privacy, security, adaptation, and secure information sharing among various stakeholders. By taking into account of the harmonization, it became essential to determine which standard had the highest interoperability with standards. This has been presented in Tables4 and 5, which has helped in confirming that HL7 and FHIR have more properties of interoperability.Q3. What are the best approaches for blockchain-based EHRs in solving this interoperability issue?The study presented different methods and techniques to solve the interoperability issues. The researchers came up with various techniques using different standards and protocols to solve the interoperability challenges. The study presented various solutions to increase the privacy, reliability, scalability, and interoperability of blockchain-based EHRs. The comparison of approaches conducted during the study shows that [42] presented the best approach for solving the interoperability issue. The author presented an interoperable information-sharing system for EHRs. The method has compliance with all standards and protocols. The techniques follow HL7 and FHIR, and ONC standards for information among EHRs. Blockchain connected off-chain storage used for data storage and on-chain authentication method implanted to satisfy the privacy and security protocols. The authors utilized the fairness algorithm for reliability and system robustness. The proposed interoperable method is HL7, FHIR, and ONC compliance. The latest version of HL7 has semantically interoperable compliance. The best approaches are mapped using the criteria of reliability (RE), the accuracy of data (AD), data privacy (DP), security (SC), scalability (SCA), access control (AC), authentication (AUTN), authorization (AUTR), robustness (RB), anonymity (ANON), confidentiality (COFD), immutability (IMMU), standards implemented, and suggested standards. The mapping and extraction of best approaches and their characteristics are presented in Table 6.Table 3
Interoperable requirements of blockchain-based EHRs.
Ref.RequirementsConceptual (syntactic and semantic)TechnologicalOrganizational and legal[35](i) Agreed vocabulary for messages and clinical documents(i) Compatibility of signals, protocols, and technical plug and play(i) Basic business process(ii) Common terminologies and information models for advanced messages(ii) Cooperation at the business level for knowledge sharing[29](i) Use standard terms for data correctness(i) To provide adequate healthcare, seamlessly exchange the health data(i) Insurance, claims, and provider information in the supportive and informative infrastructure[36](i) To evaluate the gaps, data element mapping to the standard terminologies(i) Development of logical models that are independent of platform and programming language constraints(i) Reduction in administrative burden for the reporting of federally mandated program data[37](i) Consistency in semantics(i) Resolution of technical issues of coding standards(i) Security and privacy of healthcare data[41](i) Acquisition of common dataset(i) Exchange of data between different nodes of the healthcare system using robust technical standards(i) A good healthcare informatic team to perform all activities(ii) Obtain the consensus on the dataset from the physicians(ii) A group of healthcare professionals to develop consensus on the specific project[38](i) Ability to transmit the formatted message between two or more systems(i) Specifying the data elements such as data rules, the definition of allowed values, and data format. (ii) Agreement on the technical data models to manage the data in database management systems(i) Cooperation between the informaticians, EHR IT vendors, industry process engineers, and clinicians(ii) Ability to understand and utilization of transmitted message(iii) Building a controlled vocabulary[40](i) Exchange the clinical database information(i) Adoption of previous standards for the secure transmission of data and to report the clinical data(i) Advanced adoption for government and financial incentives, and partnership between public-private entities(ii) Identification of patients and healthcare providers[39](i) The transmitting systems should understand the data without any ambiguity(i) Information transmission between several systems, and the receiving system process information to perform new actions(i) Ensuring different legal frameworks to operate the organizationsTable 4
Blockchain-based interoperable standard for EHRs.
Ref.Blockchain-based standard availableDescription[26]FHIRHL7-based resource containing data attributesStandard compliance of FHIR for information exchange[27]HL7FHIR-based emerging standardRobust performance on small devices[28]HITECHTransformation of the healthcare systemInteroperability, HER certification, and MIPS[29]PHRUsed HL7 for fast data sharing and tetheringPHR and EHIR interchangeability using APIs[30]Open EHRDesigned EHR through open-source elementsValidation of EHR standards through clinical implementations[31]DICOMSecure transfer of medical images and health historyAPIs for different health system integrations[32]SNOMED CTPresent clinical methods in EHRsAccuracy, interoperability, and consistency[33]CEN/ISO EN13606Semantic standards for EHR information sharingPrivacy and security standards for interface access[34]HIPAAPrivacy standards for patient’s data securityConfident interoperable system for EHRTable 5
Properties of blockchain-based EHR standards.
PropertiesCEN13606CENOpen EHRHL7HITECHDICOMFHIRBetter workflowYesModerateYesYesYesModerateYesReduced ambiguityModerateYesYesYesModerateYesYesQuality of careYesModerateModerateYesYesYesYesReliabilityModerateYesYesYesModerateModerateYesInformation securityModerateModerateYesYesYesModerateYesSecurity and privacyModerateYesModerateYesYesYesYesTable 6
Approaches for blockchain-based EHR interoperability challenges.
Ref.Blockchain-based EHR frameworkTechnique usedREADDPSCSCAACAUTNAUTRANONRBCOFDIMMUStandard used/ruleSuggested standard[43]1.Ciphertext-based attribute encryptionYesYesYesYesNoYesYesYesNoNoYesYesNo—[44]1. Zero-knowledge proofs2. Proxy re-encryptionNoNoYesYesYesYesYesYesNoYesNoYesHIPAAFHIR[45]1. Distributed ledger technology2. Smart contract3. Hashing algorithmNoNoYesYesNoYesYesYesYesYesYesYesNo—[46]1.SHA-256 algorithm2. RSA encryptionNoNoYesYesNoYesYesYesNoNoYesYesNoHL7, FHIR[45]1. Public key infrastructure-based asymmetric encryption2. Digital signatures to secure shared EHR dataNoNoYesYesYesYesYesYesNoNoYesYesHIPAAHL7, FHIR[47]1. Smart contract2. AWSNoNoYesYesYesYesYesYesYesNoNoYesHITECH, HL7FHIR[48]1. Smart contractYesYesYesYesNoYesYesYesYesNoNoYesHIPAA—2. Hashing method-SHA-256[49]1. Proxy re-encryption technology2. DPoS consensus mechanismYesNoYesYesNoYesYesYesYesNoNoYesNoUnified standard[50]1. Blockchain base lattice cryptography2. Deep learning as a serviceNoYesYesYesYesYesYesYesNoNoYesYesHIPAAFHIR[51]1. Cryptographic hash key2. Genetic algorithmNoNoYesYesYesYesYesYesNoYesYesYesNoStandard regulations[52]1. Smart contract2. Cryptographic techniquesNoNoYesYesYesYesYesYesNoYesYesYesHIPAAHL7[53]1. Cryptographic techniques (encryption and digital signatures)NoNoYesYesYesYesYesYesYesNoNoYesNo—[54]1. Smart contract.NoNoYesYesNoYesYesYesYesNoYesYesNo—[55]1. Public key cryptography2. Proof of work algorithm3. Smart contractNoNoYesYesNoYesYesYesYesYesYesYesHIPAAHL7, FHIR[56]1. Multi-authority attribute-based encryption2. Smart contractNoNoYesYesNoYesYesYesNoNoYesYesHIPAA—[42]1. Smart contract2. Digital identitiesYesNoYesYesYesYesYesYesNoYesNoYesONC, FHIR, Hl7New versions of HL7 to support semantic interoperability[57]1. Off-chain storage and on-chain verificationNoNoYesYesYesYesYesYesNoNoNoYesNo—


### 5.1. Open Issues in Blockchain-Based EHR

This section describes some issues and challenges in EHR systems based on this systematic literature review. Following issues have been observed, including the following:(i)
In [45], the model’s major drawback is the setup requirement at each healthcare facility. The healthcare facility must provide a minimum of one node to the blockchain to convert the servers into blockchain adapters. Another issue observed in the study is the scalability limitations of the blockchain protocol.(ii)
Dubovitskaya et al. [45] explained in their study that if the system is not deployed correctly, then it is a high risk of system failure. A healthcare provider cannot update the permission and grant; therefore, when an unconscious patient reaches a medical center, the healthcare provider cannot access the patient’s EHR information.(iii)
The privacy of patients is a significant concern in EHR systems [58]. The goal of data security is to restrict the access of unauthorized users. Data security is also a concern of healthcare providers to safeguard the patient’s health information.(iv)
Bhattacharya et al. [50] raised the issue of cost. The cost is based on the lattice model. The model contains many Gaussian distribution-based parameters. This model increases the communication cost, which is a major issue.(v)
Tanwar et al. [58] have discussed the unexpected costs that may arise throughout the implementation process. Finding financial resources for EHR adoption is one of the most challenging obstacles, especially for smaller enterprises. Physicians struggle to adapt to an EHR system that does not match their present workflow. Another significant barrier to EHR adoption is patient and provider data privacy concerns. Concerns regarding data loss as a result of a natural disaster or a cyberattack are regularly expressed by stakeholders.


## 5.1. Open Issues in Blockchain-Based EHR

This section describes some issues and challenges in EHR systems based on this systematic literature review. Following issues have been observed, including the following:(i)
In [45], the model’s major drawback is the setup requirement at each healthcare facility. The healthcare facility must provide a minimum of one node to the blockchain to convert the servers into blockchain adapters. Another issue observed in the study is the scalability limitations of the blockchain protocol.(ii)
Dubovitskaya et al. [45] explained in their study that if the system is not deployed correctly, then it is a high risk of system failure. A healthcare provider cannot update the permission and grant; therefore, when an unconscious patient reaches a medical center, the healthcare provider cannot access the patient’s EHR information.(iii)
The privacy of patients is a significant concern in EHR systems [58]. The goal of data security is to restrict the access of unauthorized users. Data security is also a concern of healthcare providers to safeguard the patient’s health information.(iv)
Bhattacharya et al. [50] raised the issue of cost. The cost is based on the lattice model. The model contains many Gaussian distribution-based parameters. This model increases the communication cost, which is a major issue.(v)
Tanwar et al. [58] have discussed the unexpected costs that may arise throughout the implementation process. Finding financial resources for EHR adoption is one of the most challenging obstacles, especially for smaller enterprises. Physicians struggle to adapt to an EHR system that does not match their present workflow. Another significant barrier to EHR adoption is patient and provider data privacy concerns. Concerns regarding data loss as a result of a natural disaster or a cyberattack are regularly expressed by stakeholders.


## 6. Conclusion and Future Work

The challenges presented in the literature include interoperability requirements, standards, and approaches to solve interoperability problems of blockchain-based EHRs. Table2 presents the requirements of interoperable blockchain-based EHRs. The requirements include data acquisition, data transmission protocols, allowed data standards and formats, and coordination levels among EHRs and vendors. The interoperable standards of blockchain-based EHRs are presented in Table 3. FHIR and HL7 are the best standards for reliability, data security, privacy, and quality assessment. In Table 5, the approaches to solve the interoperability challenges are presented. 18 selected solutions against challenges presented different methods and techniques using different standards and protocols to address the interoperability of blockchain-based EHRs. The short-listed methods improve privacy, reliability, quality assessment, authentication, and interoperability.This study may lead to future studies and research. In this study, we discuss different EHR models and answered the research questions. These answers to research questions may be utilized in the future to develop the EHR models or architectures that address the issues and challenges faced in blockchain-based electronic healthcare frameworks. Additionally, more exploration is required to resolve the current issues in blockchain-based systems combined with the Internet of things (IoT) and decentralized blockchain combined with AI, cloud computing, and big data. The organizational-level implementation should have the flexibility to adapt the cognitive solution using natural language processing and monitoring contextual facts to increase the interoperability of blockchain-based EHRs. Patient’s consolidated database might be a route in electronic health records for future research. The consolidated database will house all of the patients’ medical information. This will make it easier for doctors to access their patients’ previous data and provide a more accurate diagnosis.



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*Source: 1953723-2022-07-21.xml*