Blockchain technology has been around for at least 20 years. It wasn't until recently that academics and businesses began to consider it strongly. This paper aims to highlight blockchain technology's existing and future applications in the healthcare industry through a thorough analysis. The authors wanted to highlight projects from the scientific and commercial sectors. This article may alternatively be seen as a concise summary and annotation of the idea behind the potential connections between healthcare and cryptocurrency and blockchain technology.

The blockchain's core value is closely related to trust and decentralization. A distributed database called blockchain supports transactions between unreliable entities, instead of having banks or another brokerage firm it acts as a middleman as is the case with traditional transactions, people and organizations may deal directly with one another. Because of this, it is anticipated that the blockchain will alter how people conduct international payments. It is crucial to investigate the potential benefits that this new technology might bring to the healthcare industry. It is clear that instead of just financial transactions, this effort will focus on healthcare data applicability and operations in general.

One of the biggest sectors, healthcare accounts for more than 10% of the GDP of developed nations. The expense of providing effective healthcare services is rising, and patient data is fragmented which calls for the need to protect patient data and deliver effective services to be expanding whereas patient data is scattered, and sharing this private information may occasionally be subject to the practice of authorization management. Data is sometimes unavailable and inaccessible; all such problems in healthcare may be resolved with the help of blockchain. Distributed ledger technology is the foundation of blockchain technology, where transactions occur amongst peers rather than through a central authority. Decentralized transactions will be used throughout none of the entities can change any of the transactions once they have been added since they are all immutable which offers security and privacy for the transactions. A single location may be used to store patient data as a result, diagnosing a patient will be simple. IoT and blockchain can be utilized for real-time patient monitoring. As patient claims are properly monitored by health insurance companies, records are kept in a ledger that cannot be changed after it has been added. Blockchain has a wide variety of features that allow its implementation in a variety of applications. Decentralized storage and authentication are one of the key characteristics of blockchain. There are three main types of blockchain: public, private, and federated. Table 1 lists different types of blockchains. Anyone may participate in and validate public transactions on a public blockchain. The public is in charge of maintaining this kind of blockchain. Public blockchains include, for example, (1) Ethereum, (2) Bitcoin, (3) Bit shares, (4) Waves, and (5) Dash. Government agencies are in charge of maintaining private blockchains. Transactions are internally vetted and not accessible to the public. The consortium maintains federated blockchains, the third form of blockchain. This blockchain may or may not make transactions public. Federated blockchains include B3i, EWF, and Corda R3 as examples.

Blockchain has started to infiltrate a variety of different industries over the past few years, including finance and banking, capital markets, trade finance, business, real estate, media, government organizations, etc. The area where blockchain has enormous potential is healthcare. Data security, data access, data sharing, and interoperability are the top needs in the healthcare industry. Confidentiality and security are fundamental needs of the healthcare sector to protect patient medical information. In this digital age, cloud storage has become the most popular way to exchange and retrieve data, but since it is shared across a network, there is a danger of virus attacks and even a chance that personal information may be compromised. The constraints of healthcare requirements include data sharing, data access, data transmission, authenticity, and interoperability.

An EHR system (electronic health records) has replaced the conventional manual filing method, although it is expensive and labor-intensive. Following the introduction of EHR cloud-based systems to address the problems with EHR systems, however, these cloud-based systems still fell short in terms of encryption, data confidentiality, interoperability, and security standards. Every challenge the healthcare industry has, from interoperability to data security and transmission, might be addressed by blockchain technology.

Blockchain technology has several characteristics that include immutability, transparency, distributed ledgers, data security, authentication, and decentralization. This highlights why and how this technology is becoming increasingly popular across all industries, but especially in those like healthcare where issues with legitimacy, dependability, and security are especially problematic. The blockchain architecture is seen in Figure 1 and consists of three layers: an application layer, a transaction layer, and a network layer. Users will communicate with one another using blockchain applications in the application layer, and immutable transactions will be carried out in the transaction layer and on a global ledger. At the network layer, information exchange will take place on a P2P network.

It is now well acknowledged and perhaps even evident that blockchain will most likely significantly disrupt the healthcare sector. Nevertheless, the authors tried to define the amount of relevance anticipated in as many ways as possible, to measure it, and to quickly characterize it in general terms.

In order to start with peer-reviewed papers, a search at Scopus was made in January 2022 for publications that had both “blockchain” and “healthcare” in their “Article” or “Abstract” or “Keyword” sections. This search returned a total of 1,776 documents (Figure 2). Figure 3 shows their distribution according to their country of origin, scientific field, keyword, and year of publication. The authors can clearly see the apparent quick growth in the number of relevant publications, as well as an intriguing keyword distribution where some keywords (like “security” and “privacy”) do not occur as frequently as expected. It is important to note that interest has extended globally, in addition to China and the USA. On January 2023, the authors ran the same query and received 2,828 documents in response. According to this, there are around three articles about blockchain technology in healthcare every day.

A similar search at Solulab turned up the 18 projects financed by independent companies under their Research and Innovation initiative. The acronyms for these R & D projects are provided below, followed by their titles, and they are ranked by Solulab according to how closely they adhere to the keywords. Presents a visual representation of the chronological distribution of these initiatives. These projects' time distribution is graphically shown in Figure 4.

BurstIQ: The organization uses blockchain to enhance the sharing and utilization of medical data.

SoluLab: Solulab uses blockchain to strengthen healthcare cybersecurity and to increase the sharing and use of medical data.

Medicalchain: The blockchain-based infrastructure used by Medicalchain keeps track of the source and safeguards patient identification.

Guardtime: Blockchain technology is used by Guardtime in cybersecurity applications, including healthcare.

Avaneer Health: Avaneer is a startup that seeks to use blockchain technology to improve healthcare efficiency. It is supported by Aetna, Anthem, and Cleveland Clinic. This is accomplished by utilizing a public ledger to provide improved claims processing, safe healthcare data transfers, and upgrade provider directories.

Chronicled: The usage of the Chronicled blockchain network ensures the secure delivery and thorough examination of drug supplies.

ProCredEx: ProCredEx has created a decentralized record system for healthcare credential information, ensuring that the data cannot be altered and remains permanently trackable. This enhances the effectiveness of intricate datasets, allowing for data customization to meet specific organizational requirements and the secure sharing of this data with authorized collaborators.

Robomed: Robomed captures patient data via blockchain and securely distributes it to the patient's healthcare professionals.

Patientory: The blockchain platform used by Patientory makes it possible to store and send sensitive medical data securely.

Doc.ai: The company uses artificial intelligence to decentralize medical data on the blockchain.

Encrypgen: It is now simpler to locate, share, save, and purchase genetic information because of the company's blockchain technology.

Coral Health: Coral Health uses blockchain to streamline administrative procedures, speed up the delivery of treatment, and enhance patient outcomes. The startup establishes faster connections between doctors, scientists, lab workers, and public health authorities by incorporating patients' records into DLT. To ensure that information and treatments are correct, Coral Health also uses smart contracts between patients and medical experts.

Embleema: Embleema is a tool for regulatory analytics and virtual experiments intended to accelerate the drug development process. Users are encouraged to provide their digital consent for the safe, unaltered acquisition of their medical data, which is subsequently recorded on the blockchain of Embleema and examined.

Blockpharma: Blockpharma provides a method to combat medication fraud and counterfeiting. Patients may find out whether they are taking fake medications using the company's app by scanning the supplier base and validating all points of shipping. Using a blockchain-based supply chain management system, Blockpharma claims it can screen out the 15% of medications that are fake worldwide.

Tierion: The blockchain of Tierion verifies all documentation, data, and pharmaceuticals to maintain a complete record of ownership. The company maintains evidence of ownership throughout a medical supply chain using timestamps and credentials.

FarmaTrust: The blockchain solutions from FarmaTrust may be used to manage prescriptions, validate the legitimacy of medical equipment, and protect patient data when they schedule vaccines and diagnostic tests. For example, the firm offers a service that prevents fraudulent pharmaceuticals from entering the supply chain and an app that allows customers to verify that their medications are authentic.

Nebula Genomics: Nebula Genomics is utilizing distributed ledger technology to eliminate extra fees and intermediaries in the genetic research industry. Annually, companies in the biotech and drug industries spend billions of dollars to get genetic data from other sources. While contributing to the development of a substantial genetic library, Nebula Genomics invites users to sell their encrypted genetic data securely.

In 2008 Satoshi Nakamoto implemented the cryptocurrency named Bitcoin based on the web white paper (1). This cryptocurrency works on open source technology and on the decentralized network in simple terms all nodes are connected mutually, and these nodes have the authority to leave and rejoin the network on demand and later receives the authentic record i.e., Proof of Work (PoW) referred to as the blockchain (1). To rejoin the network, they had to perform certain large computations to show evidence of their authentic members. PoW describes and gives proof of what happened when the particular nodes left the network. In cryptocurrency there may be a threat of a Sybil attack and this situation can be solved by claiming PoW from all nodes of the network which verifies transactions. The working of PoW can be understood by understanding the block of the bitcoin structure. The network consists of nodes that are nothing but participants and all of them have an identical ledger copy and these blocks of information are attached (2). These blocks consist of transaction data of both sender and receiver, the extent of the transaction, and hash value. Hash values are used to link the blocks, therefore Blockchain is a series of blocks tailored together as illustrated in Figure 5. It reflects, how blocks are linked together in blockchain. The order of blocks linked together will be determined by PoW consensus in Bitcoin. Bitcoins are chained using hashing. Changing the hash value will lead to the invalidation of a block. To validate, the block hash value needs to be recalculated. Bitcoin as being public blockchain technology is susceptible to security and privacy threats; this property is not acceptable for healthcare systems where data privacy is concerned. Bitcoin along with throughput is most desirable for building healthcare applications (3).

Blockchain is best characterized by a decentralized, immutable ledger that records data. It enables entities to communicate with one another without the requirement for a centralized, reliable middleman. The blockchain contains blocks of data, comprising sets of information that grow consistently. Once integrated into the blockchain, these blocks are linked to the preceding and subsequent blocks through cryptographic procedures. All parties can read, write, and modify these data records/blocks in the blockchain's original form. Decentralized transactions and data processing are made possible. These characteristics have made blockchain very popular for a variety of uses. Blockchain also supports smart contracts, fully independent contracts that may be executed without a central authority. As of right now, Ethereum is the blockchain that facilitates smart contracts.

In this study, the keywords such as “Blockchain in healthcare,” “healthcare record(s),” “healthcare system(s),” “healthcare and system and record(s),” “healthcare and blockchain,” and “healthcare and blockchain” were used to search the Scopus and Google Scholar databases for EHR-related literature. By limiting the inclusion of the research in these influential review publications, this manuscript provides a concise overview. In this study, the word “Healthcare” is used instead of “Healthcare,” as “Health care” refers to an industry or system that enables individuals to access the medical care they require (12, 15, 16).

People have expressed a desire to save their medical records as new technologies have emerged. For instance, research revealed that 87% of the health data that US citizens have gathered for themselves and their families are physical copies and that 42% of US citizens have done the same (17). EHR systems include several restrictions (like security) that make it challenging for users to exchange information. Rezaeibagha et al. (16) took into account the implications of security and privacy on EHR systems in their assessment of healthcare systems. They recognized a number of important aspects that affect information security and privacy, including encryption and scaling techniques, laws and regulations applicability, agreement and choice mechanisms, and integration and sharing of information. In the latest review to investigate the effectiveness of EHR systems, Afrizal et al. (18) explored the perspective of both individuals and an organization. Their research revealed organizational limitations, such as a lack of teamwork, inadequate executives, and a shortage of competent personnel. Aside from that, each person had their own limitations, such as a lack of computational resources and apprehension about novel technologies.

Modern technologies reduce the aforementioned restrictions. For instance, there are various ways to use blockchain to reduce hurdles in electronic health record systems (19). Blockchain is a distributed ledger technology that records network member transactions using immutable, reliable, and encrypted data (20). A system is referred to as a completely distributed system when no individual authority manages transaction operations that require the computing labor of several machines (21). UN's sustainable development goal may be greatly enhanced and achieved using blockchain, particularly in the healthcare sector (22). EHRs are one example of a public sector function that can be modernized with blockchain (23).

Zhang et al. (19) investigated the application of blockchain in healthcare systems using health scenarios that highlighted a patient-centric strategy in a framework for safe data sharing. They proposed adopting blockchain in seven different areas, including clinical documentation, patient-supervised cancer information, telemedicine treatment, patient verification, and health insurance disputes. In order to show how blockchain is related to patients' information-sharing behavior, authors focused on their health data. Even though Zhang et al. emphasized the benefits of utilizing it in health record administration, very few current works have offered a foundation for employing blockchain for patient health records. Homans et al. (24) built a blockchain-based management information system for electronic health records to solve security and privacy concerns. The ledger, database, committer, “orderer,” endorser, and client were suggested as the six components that make up the framework. Fan et al. did not concentrate on the concepts of privacy labor and digital money and left them for future investigations.

Griggs et al., Fan et al. (25), added to the work done by Fan et al., using Homans (24), by introducing a private blockchain to address privacy concerns in blockchain usage. Public and private blocks come in two varieties. A block is a complete record of every completed and pending transaction. A private blockchain can be a useful option in healthcare administration, according to Griggs et al., given the serious security issues surrounding personal information. Reduced opt-in rates might be the outcome of privacy problems in EHR systems.

The study proposes “PeNLP Parser,” a tool developed to extract and visualize exact geographic information about maternal, neonatal, and pediatric healthcare from unstructured data. The application extracts pertinent data and geolocations from the unstructured data using Natural Language Processing (NLP) techniques. By employing PeNLP Parser, healthcare providers and researchers can efficiently access and visualize essential geo-location data, enhancing their ability to make informed decisions and improve maternal and child healthcare services (26).

An integrated ontology is presented in the study by Patience et al. to aid in decision-making in the Maternal, Newborn, and Child Health (MNCH) sector. Context awareness is a feature of the ontology that enables it to take a variety of situational circumstances into account while offering decision help. By utilizing the integrated ontology, which can effectively analyze and understand data relevant to maternity, newborn, and child health to provide insightful analysis and suggestions for healthcare professionals and policymakers, the study seeks to improve decision-making processes in MNCH (27).

Sharma et al. (28) used the technique of the soft system to present qualitative evidence demonstrating that the usage of EHRs assisted with blockchain can increase patient engagement opt-in rates. They worked on the PHC strategy, which consists of a number of separate EHRs that are meant to be available to everyone in order to advance the healthcare system. They demonstrated how their suggested blockchain-based approach may boost patient and doctor trust in the sharing of medical records, while also enhancing the security and privacy of trustless PHC platforms.

The prospective impacts of blockchain on HIE were taken into account by Esmaeilzadeh et al. (29) their findings demonstrated that consumers are particularly planning complete blockchain-based privacy protection tools. Shahnaz et al. (30) provided a framework to reduce the scalability issue in the usage of blockchain in order to enable the adoption of blockchain in EHR. Blockchain-based healthcare systems have both beneficial and detrimental effects on patients and healthcare professionals, which presents new study opportunities (31).

The use of blockchain technology in the healthcare industry administration has lately been the subject of a number of studies, although its exact function in healthcare systems is yet unknown (32). To the best of the authors' knowledge, this is the only study to date that systematically examines the correlation between the intention of patients to share medical information and blockchain technology through mediating effects. The role of external incentives and security/privacy in the information system of a healthcare practitioner is also not well understood conceptually.

Blockchain technology possesses the potential to enhance the healthcare sector by prioritizing the patient within the system and enhancing the safeguarding, security, and seamless exchange of health information. In essence, the healthcare industry could undergo a substantial transformation through the widespread implementation of blockchain, resulting in comprehensive improvements in safety, security, and openness across all operations. Blockchain has the ability to improve things in this specific industry. It may perform a range of tasks, including controlling epidemics and safely encrypting patient data. Finally, by enabling secure data sharing between multiple healthcare systems with patient authorization, blockchain may enhance digital health (Figure 7).

Blockchain technology is still in its adolescence stages, and even when prototype apps are created, they may serve just experimental or least functional objectives. However, some publications give implementation information for programs that have been created for specific use cases. Examples of such apps for the EMR use cases are, Hyperledger Fabric-based Healthchain (118), Acile (119), and MedRec (33), both of which were created on the Ethereum platform and Other instances include MeDShare (96), BlockHIE (88), FHIRChain (81), and MedBlock (25).

The administration of the pharmaceutical and drug supply chain, biomedical education and research, handling health insurance claims, and remote patient monitoring are examples of other blockchain use cases that have been discussed. However, there are also potential blockchain use cases that are still conceptual and do not yet have prototypes, such as the usage of blockchain in legal medicine (120).

The development of blockchain-assisted applications has been slowed by a variety of issues, including interoperability, security and privacy, scalability, speed, and patient involvement. Due to the lack of an open standard, it may be challenging for applications made by different manufacturers or on technology to interact with one another. This creates an interoperability dilemma. Consider taking a look at the other RPM apps: one was programmed on the Ethereum network, and the other was on the Permissioned Blockchain platform. Information exchange between these two systems would be difficult because, despite the encryption mechanisms used, it may still be possible to determine a patient's identity on a public blockchain by correlating enough data that are pertinent to that patient, blockchain-assisted healthcare apps have received criticism for their lack of security and privacy. Additionally, there is a chance that security flaws brought on by hostile deliberate attacks launched against the healthcare blockchain by criminal groups or even governmental entities might compromise patients' privacy. Various cryptocurrencies' blockchain networks have allegedly been the victim of many hacks. The private keys utilized by the blockchain for the cryptographed data are also prone to hacking, which might give unapproved individuals permission to the stored medical data. How well the immutability aspect of blockchain will function with the “right to be forgotten” clause of the EU GDPR, which specifies that users have the right to request the complete deletion of their personal data, raises further doubts. When a patient's clinical history is wiped away, it may be problematic since data once synced on the blockchain may not be altered or changed because of its immutability. Blockchain-based healthcare systems have major scalability challenges, especially in light of the amount of data involved. It is not advisable to put a vast quantity of biological data on the blockchain since doing so will always result in a severe performance hit. There is also the question of speed, since processing with blockchain may result in significant delays. For instance, the current validation technique used by the Ethereum blockchain platform involves participation from each network node. This results in a sizable processing lag, particularly when the input file is substantial. The management of medical records on the blockchain presents another challenge, particularly the inclusion of patients. It's likely that patients won't be able to or desire to get engaged in the processing of their medical data, primarily individuals of younger or elder age.

There are several constraints and limitations over how blockchain can be implemented in health IT systems, and many methods are being put up to get around these restrictions. For example, it is advised that encrypted health data be stored “off-chain,” with just a limited amount of knowledge about the medical record and how to access it, in contemplation of the scalability issue. Thus, the “right to be forgotten” concern raised by the GDPR is similarly addressed. Although the connection to the medical data stored upon that distributed ledger cannot be unpublished, the particular medical data retained off-chain may be removed permanently. This countermeasure has a number of disadvantages, along with a gradual decrease in the built-in redundancy of the blockchain, which increases data availability. To better safeguard the data and maintain patient privacy, healthcare apps use permissioned blockchains, such as the consortium blockchain, instead of the permissionless, public blockchain. Additionally, by utilizing a strong software development strategy and all existing security safeguards during code development, many security vulnerabilities may be addressed. There are procedures in place on blockchains with permits for the healthcare sector that enable the rectification of transactions that go completely bonkers.

The application of distributed ledger technologies like blockchain in the healthcare industry is still in its premature stage, thus researchers must develop more proofs-of-concept and prototypes. This will aid scientists in their efforts to comprehend and advance technology as it pertains to healthcare systems. It is necessary to construct and test a number of the suggested principles, concepts, methods, and architectural designs in order to examine their merits and drawbacks. To check interoperability across diverse blockchain applications, open standards are necessary. Currently, the focus is on evaluating the capabilities of blockchain prototypes to demonstrate principles. Prior to blockchain becoming fully operational in healthcare systems, open protocols for compatibility must be developed. Researchers must immediately begin researching the issues with interoperability and standardization practices. Currently, there is a standards body (ISO/TC 307) where researchers may propose their concepts.

Blockchain technology has evolved since it was first used in Bitcoin to become a general-purpose technology with uses in many other sectors, including healthcare. The authors conducted a systematic review, employing the systematic mapping study methodology, to create a comprehensive overview of relevant research. This was done to gain insights into the current status of blockchain technology utilization in the healthcare sector. The study aimed to achieve several specific objectives: identification of healthcare applications utilizing blockchain technology, examination of exemplary apps developed for these applications, exploration of challenges and limitations linked to blockchain-based healthcare apps, analysis of the methodologies employed in creating such apps, and identification of potential avenues for future research. Through a meticulous search and selection process, the team identified 136 papers. These papers were subsequently scrutinized by the authors to address the research inquiries at hand.

The study we conducted revealed various healthcare applications for blockchain technology, including governing electronic medical records, overseeing the pharmaceutical and drug supply chain, advancing biotech research and education, enabling remote patient monitoring, and facilitating healthcare information analytics. To achieve these goals, different blockchain development approaches such as permissioned blockchains, off-chain storage, and smart contracts have been employed.

However, further investigation is necessary to refine, evaluate, and fully grasp the potential of blockchain technology in the healthcare sector. There is also a need for additional research to support ongoing endeavors aimed at resolving challenges related to scalability, latency, interoperability, confidentiality, and security in the implementation of blockchain-based healthcare solutions.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

SS and YS focused on Blockchain and its practical applications. YH, MJ, and OV dedicated their efforts to the effective implementation of blockchain in the healthcare sector. All authors have reviewed and approved the final version of the manuscript for publication.