Search strategy

To identify relevant SLRs focusing on the application of blockchain technology in healthcare, we developed a comprehensive search strategy, which involved a systematic and structured search across various databases and sources to ensure a thorough coverage of the topic.

Data sources

We conducted searches in several electronic databases recognized for their comprehensive coverage of literature in the fields of technology and healthcare. These included:

• PubMed

• IEEE Xplore

• ACM Digital Library

• Science Direct

• Springer Link

Additionally, to ensure exhaustive coverage and capture literature that might not be indexed in the aforementioned databases, we conducted supplementary searches in:

• Google Scholar

Search terms and strategy

The development of the search strategy involved an integration of specific keywords and Boolean logic. The core search terms employed were “blockchain”, “healthcare”, and “systematic literature review”. These terms were interconnected using Boolean operators. For instance, the search query “blockchain” AND “healthcare” AND “systematic literature review” was utilized. To ensure compatibility with the unique indexing systems and search functionalities of each database, the search queries were customized accordingly. The temporal scope of the search was confined to the period from 2008, marking the publication of Bitcoin’s white paper, to December 2023, the knowledge cutoff date of this study. The retrieved articles were then listed according to their relevance to the search purposes.

Study selection

As shown in Table 2, the initial results were screened based on titles and abstracts to identify studies that potentially met our inclusion criteria. The inclusion criteria were:

• Articles focusing on the application of blockchain in healthcare.

• Studies that were SLRs.

• Publications in English.

Exclusion criteria included:

• Non-peer-reviewed articles.

• Articles not relevant to the core focus of blockchain in healthcare.

• Studies lacking a systematic approach in methodology.

Then, the duplicates were removed using digital object identifiers (DOIs).

Data extraction and management

To answer the research question proposed, selected articles underwent a full-text review for detailed analysis. Relevant information was extracted and compiled into a predefined data extraction template, which included:

• Study objectives and research questions.

• Key findings and conclusions.

Criteria for blockchain application in healthcare data sharing

In examining the applicability of blockchain technology for healthcare data sharing, our analysis identified eight critical criteria: scalability, privacy, integrity/immutability, interoperability/accessibility, transparency, patient involvement, legal compliance, and cost/incentive, as shown in Table 3. These criteria, combined with the flowchart by Wüst and Gervais [8], collectively form a comprehensive framework, guiding the evaluation of blockchain’s application in healthcare data sharing.

Do you need a blockchain in healthcare data sharing? A flowchart

Determining the suitability of blockchain technology for healthcare applications requires a systematic evaluation of various factors. To address this, we have developed a comprehensive decision-making flowchart, as shown in Figure 2.

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Figure 2. 

The decision-making flowchart

The flowchart serves as a valuable tool for healthcare practitioners, facilitating informed decision-making regarding the implementation of blockchain solutions. It encompasses factors such as the requirements of data sharing, data integrity, and immutability, the identity verification and trustworthiness of healthcare actors, patient involvement, and public verifiability. Each step of the flowchart is accompanied by three elements, a rationale, term definitions, and a decision pathway. The rationale explicates the purpose of each step, ensuring that stakeholders understand the importance of the considerations involved. Term definitions are provided to clarify technical and healthcare-specific terminology, catering, especially to practitioners less familiar with blockchain technology. Finally, the decision pathway guides users to subsequent steps based on their specific circumstances and requirements.

Step 1: Do you need to share data?

• 1.

  Rationale

  This initial question focuses on the necessity of data sharing. It serves as the primary filter for assessing the applicability of blockchain in the health domain.

• 2.

  Term definition

  “Data” refers to information that is relevant to the health domain, often related to the physical, mental, and social well-being of individuals or populations. This encompasses a wide range of data types including, but not limited to, medical histories, diagnostic results, treatment information, and lifestyle specifics [21].

• 3.

  Decision pathway

  If a healthcare organization does not have a requirement to share data, the integration of blockchain may not offer substantial benefits. Thus, this question lays the foundation for the subsequent inquiries and decision-making processes.

Step 2: Can you share via trusted third parties?

• 1.

  Rationale

  This step examines the necessity of trusted third parties in traditional and centralized healthcare data sharing systems [68], such as hospitals, insurance companies, and government agencies. It directly confronts the scalability challenge of transitioning traditional, centralized healthcare data sharing to a decentralized blockchain approach [21, 51, 52]. This step also prompts an evaluation of whether the existing infrastructure, predominantly based on trusted third parties, meets the demands of healthcare data sharing. It invites stakeholders to assess the scalability challenge of current blockchain technology. The decision to integrate blockchain in healthcare should consider scale and balance the benefits of decentralization against the established trust in centralized systems.

• 2.

  Term definition

  “Trusted third party” refers to centralized entities responsible for storing, processing, and sharing health information [25].

• 3.

  Decision pathway

  In the healthcare sector, trusted third parties offer established systems for data sharing, yet this comes with potential drawbacks, including increased vulnerability to data breaches, alongside a shift in control and trust towards these entities. On the other hand, blockchain technology provides a decentralized framework, ensuring data owners maintain ownership over their data, dictating access and sharing terms. This approach may mitigate trust and data security concerns; however, as a novel technology, it is challenged by efficiency and difficulties in integrating with existing healthcare systems. Therefore, if sharing via trusted third parties is possible, sharing with the support of blockchain technology may be unnecessary. This is particularly true if high transaction speed is required. However, if there is a need to scale data sharing to multiple actors and a trusted third-party model is not possible or not available, then a blockchain model could contribute.

Step 3: Is data integrity and immutability crucial?

• 1.

  Rationale

  In this step, data integrity and immutability ascend to paramount importance [57, 63, 65]. This step prompts stakeholders to consider whether the existing data sharing mechanisms afford sufficient control over the data’s integrity once it is out of their direct custody. It challenges them to evaluate if traditional systems offer adequate safeguards against unauthorized alterations, deletions, or breaches.

• 2.

  Term definitions

  “Data integrity” entails the accuracy and consistency of data over its lifecycle [38]. “Data Immutability”, on the other hand, refers to the data’s unchangeability once recorded, preventing unauthorized alterations that could compromise its reliability [62].

• 3.

  Decision pathway

  • If data integrity and immutability are not deemed crucial for a specific healthcare data sharing scenario, the necessity for employing blockchain technology is reduced. In these cases, the complexities and costs associated with implementing a blockchain solution may not be justified because the data in question does not significantly impact patient care outcomes, regulatory compliance, or where traditional database systems provide sufficient security and audit capabilities.

  • When data integrity and immutability are crucial in this context, blockchain technology emerges as a pivotal solution. Blockchain’s inherent features, such as decentralized storage, cryptographic hashing, and consensus algorithms, provide a potential solution when maintaining control over data integrity and immutability is a primary concern in data sharing scenarios.

Step 4: Is transparency towards actors important?

• 1.

  Rationale

  Transparency is not just a preference but a necessity in modern healthcare data management [69, 70]. It fosters trust among stakeholders [63] and aids in compliance with regulatory standards [48]. Given the sensitive nature of healthcare data, stakeholders must be assured that the data is handled appropriately and that activities are traceable and accountable [55].

• 2.

  Term definition

  “Actors” refers to all individuals and entities interacting with the shared data, including patients, healthcare providers, insurance companies, administrators, and possibly others like researchers or pharmaceutical companies [55, 59].

  “Transparency” within a healthcare system refers to the extent of access and visibility offered to various stakeholders. Generally, it includes a transparent and auditable record of one or many of the following: data access, processing, and sharing. In the context of blockchain-based systems, the level of transparency varies depending on the type of blockchain [63]. This transparency ensures that all actions are conducted with integrity and align with established protocols and regulations [55].

• 3.

  Decision pathway

  When evaluating blockchain integration for healthcare data sharing, it is essential to assess the necessity of transparency across all healthcare actors, thereby guiding the selection of the blockchain type.

  • For environments where transparency needs are balanced with privacy concerns, a private permissioned blockchain could be more appropriate. Such a blockchain allows for selective visibility of transactions, ensuring only authorized parties can access specific data. It supports regulatory compliance and protects sensitive information while offering transparency to those granted access.

  • Conversely, in a scenario where transparency is required to build trust and ensure accountability among all actors, exploring a public permissioned or permissionless blockchain might be advisable. It provides an open environment where data transactions are visible to anyone, enhancing transparency but requiring careful consideration of privacy and data sensitivity.

Step 5: Are the identities of actors known?

• 1.

  Rationale

  In healthcare scenarios where the identities of the actors are known, the data sharing is typically limited to a few organizations identifying a solution to share information. In other health scenarios, the identities of the actors are not well known due to a need for information sharing across multiple organizations. In this later case, the information is generated or collected in different technical systems thereby, interoperability becomes an important concept linked to this question. Therefore, identifying actors within a data-sharing network aligns with ensuring interoperability, which is significant in healthcare [71, 72]. Interoperability, in this context, refers to the ability of different entities to communicate, exchange data, and use the information that has been exchanged efficiently and effectively based on the identification of healthcare actors [73]. This step underscores the importance of interoperable systems in ensuring that the identities of all participants in the healthcare data sharing process are accurately known and verifiable. The level of identity disclosure directly impacts the appropriate blockchain type [74].

• 2.

  Term definition

  “Known identities” implies that the real-world identities of these actors are verified and authenticated within the system [74].

• 3.

  Decision pathway

  Identifying all participants is crucial for determining the type of blockchain when integrating it into healthcare data sharing.

  • If the identities of all actors do not need to be publicly known or verified, a public permissionless blockchain may be considered. It allows for anonymous or pseudonymous participation, facilitating a broader engagement. However, interoperability may be challenging where identity verification is necessary.

  • On the other hand, if verifying the identities of all healthcare actors is essential, a public permissioned blockchain would be more suitable. This approach supports interoperability by enabling secure, authenticated interactions across different actors. It also ensures that each actor’s identity is known and verified, enhancing trust and compliance with healthcare regulations.

Step 6: Are all actors trusted?

• 1.

  Rationale

  Trust among actors in a healthcare data-sharing context is important to ensure that the data is not misused and that all parties adhere to the agreed-upon protocols and ethical standards. In a blockchain network, trust can be related to confidence in the actors’ behavior and the security of the transactions [24, 75]. The level of trust among the actors will influence the governance model and the degree of decentralization appropriate for the blockchain system [6, 76].

• 2.

  Term definitions

  “Trusted actors” refers to entities and individuals that have established a record of reliability and ethical handling of healthcare data. Trust can be derived from historical interactions, reputation, or regulatory compliance [71]. In blockchain terms, this might translate into the need for less stringent consensus mechanisms or the ability to operate with a higher degree of autonomy within the network [55, 59].

• 3.

  Decision pathway

  • If all actors are trusted, a private blockchain might be sufficient. It could be suitable for a group of healthcare providers or between trusted entities with existing relationships. It leverages the inherent trust to ensure data security and compliance while benefiting from advantages like immutability and transparency. It is sufficient for controlled, secure data exchange, where wide-scale decentralization is less critical, allowing for efficient and streamlined operations within the trusted network.

  • If there is a mix of trusted and untrusted actors, or if trust needs to be established through system architecture, a public permissioned blockchain may be necessary with further consideration. It allows for a more controlled environment than a public permissionless blockchain, which balances between openness and the need for specific restrictions. It requires actors to have permission to join, which can help main security and trustworthiness while still leveraging the benefits of blockchain technology to ensure data integrity.

  • In cases where no actor is fully trusted, a public permissionless blockchain might be employed, combining further filtering factors. Here, trust is not placed on any single actor but on the blockchain protocol and the distributed network of participants to maintain integrity. This approach ensures transparency and accountability, making it suitable for scenarios requiring high levels of trust and security without centralized control.

Step 7: Do you need to involve patients?

• 1.

  Rationale

  In healthcare, patient-centric care models are increasingly important, and involving patients in their data management is a key aspect of this [77]. Patient involvement can empower individuals to take control of their health information, allowing them to grant or revoke access to their data [78, 79]. Blockchain can offer a platform where patients can actively engage with their data securely and transparently [80].

• 2.

  Term definition

  “Patient involvement” refers to the participation of patients in managing and controlling access to their healthcare data. It includes viewing their medical records, sharing them with healthcare providers, and possibly contributing data from wearables or other personal health devices [78, 81]. Patient involvement could be direct or indirect. Direct patient involvement refers to sharing information directly, empowering patients to manage and control access to their healthcare data actively. Indirect patient involvement refers to the data sharing being pseudonymous or anonymous, where direct identifiers are removed from healthcare data to protect patient privacy, and data owners retain a mapping between the identities of patients and their de-identified records.

• 3.

  Decision pathway

  • If patient involvement is required, a public permissionless or permissioned blockchain could be suitable, combined with further discussion. Such blockchains facilitate patient interaction with their healthcare data and allow patients to claim ownership of their healthcare data, placing them at the center of healthcare data sharing.

  • If patient involvement is not required, a private blockchain or a public permissioned blockchain may be adequate, where healthcare providers or administrators hold control over data access and management, facilitating efficient data sharing and management within the healthcare sector. It focuses on operational efficiency and compliance with regulatory standards without requiring direct patient involvement in the data sharing process.

Step 8: Is cost a limiting factor?

• 1.

  Rationale

  Cost is a significant consideration for healthcare organizations when integrating blockchain technology, which can vary widely depending on the network type and the implementation scale [4]. The decision balances the financial resources available with the benefits a blockchain solution could provide.

• 2.

  Term definition

  “Cost” in the context of integrating blockchain technology in healthcare data sharing encompasses the financial expenditure required for the system’s initiation and maintenance, including upfront investment needed for hardware, software, and expert labor and the recurrent costs like energy consumption, system upgrades, and security measures. In the context of blockchain, transaction fees should also be considered. These are necessary considerations in deciding the type and scale of blockchain implementations suitable for healthcare organizations [3].

• 3.

  Decision pathway

  • If cost is a limiting factor, a public permissioned blockchain might be more appropriate, leading to lower operational and infrastructure expenses due to restricted access and optimized network requirements.

  • In cases where the budget allows for a more robust and decentralized solution, and the benefits of such a solution outweigh the costs, a public permissionless blockchain could be considered. Public permissionless blockchains stand out for their open and decentralized nature, leading to higher operational costs due to the extensive computational power needed to validate transactions and maintain the network.

Step 9: Is public verifiability required?

• 1.

  Rationale

  Public verifiability is an important factor in the choice of blockchain architecture, especially in the healthcare sector, where the integrity of data and the accountability of actors are subject to scrutiny by external parties [54, 67]. In such scenarios, the blockchain’s inherent audibility feature becomes invaluable, as it provides a tamper-proof ledger where all transactions are recorded in a manner that is secure and accessible for verification purposes. The decision here will largely depend on the nature of the data being shared and the broader objectives of the healthcare organization regarding public trust and accountability [8].

• 2.

  Term definition

  “Public verifiability” means the capability of any external party, without necessarily being part of the blockchain network, to validate the data and transactions on the blockchain [8]. This feature is critical in ensuring transparency and integrity of data, where the public or independent entities can audit and confirm the legitimacy of the information stored on the blockchain [8].

• 3.

  Decision pathway

  • If public verifiability is a requirement, indicating that the recorded data is of public interest and not sensitive, a public permissioned blockchain is likely an appropriate choice. It allows for public verification while controlling access and maintaining some level of privacy and security, fostering transparency and trust, particularly in public health data or research findings.

  • In cases where public verifiability is not essential, or data sensitivity necessitates more restricted access, a private blockchain might be more suitable. This blockchain limits verifiability to specific, authorized parties, offering a controlled environment while maintaining security and privacy.

Evaluating the suitability of blockchain in healthcare: case studies

To evaluate the utility of our decision-making flowchart in guiding blockchain implementation decisions within the healthcare sector, we analyze MedRec [27], Drugledger [28], iWellChain [82], DACIL [83], REALM [84], ChainSure [32], and LUCE [85], as shown in Table 4. In this table, the category column classifies each project into functional areas. The case description provides brief summaries of each project’s objectives. Assumptions detail the underlying premises for each project’s evaluation, focusing on aspects like data privacy and cost distribution. The decision path outlines the step-by-step choices made based on the decision-making flowchart, indicating decisions with ‘Yes’ or ‘No’. Finally, the final outcome column shows the type of blockchain technology adopted by each project. Detailed analysis can be found in Supplementary material.

To have a more comparative understanding of our decision-making framework, we integrate the case studies into the original flowchart, as shown in Figure 3. The color-coded paths indicate different routes that can be taken depending on the answers to the yes/no questions at each decision point. These paths represent distinct case studies, each with unique considerations and endpoints.

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Figure 3. 

Case studies of the decision-making flowchart

Implications of the results for healthcare professionals and policymakers

The findings of this review, resulting in a decision-making flowchart for determining the suitability of blockchain in healthcare applications, have significant implications for healthcare professionals and policymakers.

For healthcare professionals, the flowchart serves as a valuable tool for assessing the potential benefits and challenges of integrating blockchain into their practice. It guides them in considering factors such as the necessity of data sharing, trusted third parties, date immutability and integrity, participant knowledge, patient involvement, and public verifiability. By leveraging blockchain technology in appropriate scenarios, healthcare professionals can enhance data security and privacy, improve interoperability, and enhance patient care coordination [3]. Understanding the conditions under which blockchain is most likely to yield positive outcomes is essential for effective utilization by healthcare professionals.

Policymakers can also benefit from the insights provided by this study to develop appropriate regulations and guidelines regarding the implementation of blockchain in healthcare. The flowchart offers policymakers a comprehensive understanding of the factors to consider when assessing the feasibility associated with adopting blockchain technology. Policymakers can utilize this information to shape policies that support innovation while ensuring privacy, security, and ethical use of blockchain in healthcare. Additionally, they can address legal and regulatory challenges that may arise, promoting responsible and effective integration of blockchain in the healthcare ecosystem [86].

Identification of gaps in the current literature and areas for future research

This review has also identified gaps and areas for future research in the healthcare blockchain field. While the literature on this topic has expanded, certain aspects require further investigation.

Firstly, more empirical studies are needed to evaluate blockchain solutions’ actual implementation and impact in real-world healthcare settings. While existing literature provides theoretical insights and frameworks, empirical evidence of blockchain applications’ effectiveness, efficiency, and user experiences in healthcare is limited. Future research should focus on conducting expert interviews, stakeholder surveys, and pilot projects to assess the practical implications, challenges, and benefits of implementing blockchain technology across various healthcare domains and organizational contexts.

Secondly, blockchain’s ethical, legal, and social implications in healthcare require further exploration. As blockchain technology becomes more prevalent in healthcare, examining ethical considerations related to patient privacy, data ownership, consent management, and data governance is crucial. Additionally, legal and regulatory frameworks should be developed to address unique challenges posed by blockchain, such as jurisdictional issues, liability, and dispute resolution. Future research should provide comprehensive guidance on the ethical and legal aspects of blockchain implementation, facilitating responsible and transparent use of the technology in healthcare.

Furthermore, as the volume and complexity of healthcare data continue to rise, the scalability of blockchain solutions becomes a critical concern. Scalability in this context refers to the ability of blockchain networks to handle increasing amounts of data without compromising on speed or efficiency. Efficient data processing is crucial in healthcare, where real-time data availability can significantly impact patient care and outcomes. Future research needs to focus on enhancing the scalability of these networks through innovative approaches such as sharding, which divides the network into smaller, more manageable segments, or through layer two solutions that process transactions off the main blockchain to decrease load and increase speed. This will ensure that as healthcare data grows, blockchain networks remain efficient and responsive to the needs of the industry.

Lastly, interoperability between blockchain platforms and existing healthcare systems is critical for successfully adopting and implementing blockchain technology in healthcare. This interoperability involves the seamless integration and exchange of data across different blockchain platforms, blockchain networks, and legacy healthcare systems. The challenge lies in creating a standardized framework for secure, reliable, and efficient data exchange. Future studies should explore the development of technical solutions and standards that facilitate this integration. Adopting common standards can significantly enhance the potential for blockchain to support diverse healthcare applications, from patient records management to supply chain transparency, thereby improving healthcare delivery.

Limitations of the review and suggestions for improving future studies

Despite employing a rigorous methodology, this review has some limitations. Firstly, it relies on existing SLRs as the primary source of information, which may vary in quality and coverage. To address this, future studies could consider incorporating primary research studies to complement findings from SLRs.

Secondly, the validation of the decision-making flowchart is currently conducted using case studies, primarily due to constraints in time and resources. To enhance the validity of the flowchart in future iterations, future studies should incorporate a broader range of methods, such as expert interviews, stakeholder surveys, and pilot projects. These additional methods will gather diverse perspectives and more comprehensive feedback, contributing significantly to developing a more robust and reliable decision-making tool.

Lastly, the decision-making flowchart presented in this study is based on synthesizing existing literature. It may not capture all possible factors or considerations relevant to specific healthcare contexts. Therefore, healthcare professionals and policymakers should contextualize the flowchart within their unique organizational settings and critically reflect before making decisions about adopting blockchain technology.

In conclusion, this tertiary review underscores the potential benefits and complexities of integrating blockchain technology in healthcare. The study developed and validated a decision-making flowchart to assist healthcare professionals and policymakers in making informed decisions about blockchain applications in healthcare. The flowchart, tested through various case studies, offers a structured approach to evaluating the viability and implications of blockchain technology. Our findings stress the necessity of assessing key factors such as scalability, privacy, interoperability, and legal compliance to harness blockchain’s benefits effectively. The inclusion of practical case studies confirms the applicability of the decision-making tool across various healthcare domains, promoting a responsible and informed approach to adopting blockchain technology in the healthcare sector.