Blockchain-based privacy and security preserving in electronic health: a systematic review

Abstract

In today’s world, health and medicine play an undeniable role in human life. Traditional and current Electronic Health Records (EHR) systems that are used to exchange information between medical stakeholders (patients, physicians, insurance companies, pharmaceuticals, medical researchers, etc.) suffer weaknesses in terms of security and privacy due to having centralized architecture. Blockchain technology ensures the privacy and security of EHR systems thanks to the use of encryption. Moreover, due to its decentralized nature, this technology prevents central failure and central attack points. In this paper, a systematic literature review (SLR) is proposed to analyze the existing Blockchain-based approaches for improving privacy and security in electronic health systems. The research methodology, paper selection process, and the search query are explained. 51 papers returned from our search criteria published between 2018 and Dec 2022 are reviewed. The main ideas, type of Blockchain, evaluation metrics, and used tools of each selected paper are discussed in detail. Finally, future research directions, open challenges, and some issues are discussed.

Full text

Blockchain-based privacy and security preserving
in electronic health: a systematic review
Kianoush Kiania
1
&Seyed Mahdi Jameii
2
&Amir Masoud Rahmani
3
Received: 3 January 2022 /Revised: 9 January 2023 /Accepted: 31 January 2023
#The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2023
Abstract
In today’s world, health and medicine play an undeniable role in human life. Traditional
and current Electronic Health Records (EHR) systems that are used to exchange infor-
mation between medical stakeholders (patients, physicians, insurance companies, phar-
maceuticals, medical researchers, etc.) suffer weaknesses in terms of security and privacy
due to having centralized architecture. Blockchain technology ensures the privacy and
security of EHR systems thanks to the use of encryption. Moreover, due to its
decentralized nature, this technology prevents central failure and central attack points.
In this paper, a systematic literature review (SLR) is proposed to analyze the existing
Blockchain-based approaches for improving privacy and security in electronic health
systems. The research methodology, paper selection process, and the search query are
explained. 51 papers returned from our search criteria published between 2018 and
Dec 2022 are reviewed. The main ideas, type of Blockchain, evaluation metrics, and
used tools of each selected paper are discussed in detail. Finally, future research direc-
tions, open challenges, and some issues are discussed.
Keywords Electronic Health Records (HER) .Blockchain .Security .Privacy .Smart contract .SLR
1 Introduction
Nowadays, healthcare is considered to be one of the most important human concerns. A lot of
data related to healthcare are generated, stored, and reused frequently. One of the most important
subsets of healthcare systems is Electronic Health Records (EHR). Electronic patient records
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https://doi.org/10.1007/s11042-023-14488-w
*Seyed Mahdi Jameii
sm.jameii@iau.ac.ir
1
Department of Computer Engineering, Science and Research Branch, Islamic Azad University,
Tehran, Iran
2
Department of Computer Engineering, Shahr-e-Qods Branch, Islamic Azad University, Tehran, Iran
3
Future Technology Research Center, National Yunlin University of Science and Technology, 123
University Road, Section 3, Douliou, Yunlin 64002, Taiwan

provide many opportunities for healthcare stakeholders. For example, it allows medical records to
be accessed by patients and avoids expensive tests, radiology, and repetitive imaging. Moreover,
even if the patient is treated in different medical centers or in hospitals located in different cities,
provinces, or other countries, physicians based in all those medical centers can access the patient’s
records across far distances from each other using EHR. Another advantage of using EHR is
having access to a history of medications used by the patient, which will help physicians in
prescribing a new drug for the patient. Another advantage of using EHR is the use of patients’
medical records for research purposes and finding new treatment methods.
One of the basic challenges of using EHR in healthcare is how to preserve the patient’s
privacy. With the wide access to patient records, the patients’privacy is an important challenge.
Another challenge for EHR is that the patient does not own his/her data and instead, it is the
medical centers who own the patient’s data. Physicians and researchers can access a patient’s
EHR without his or her consent to use these data for treatment and research purposes, and this is
one aspect of the patient’s privacy. From a security perspective, using EHR brings up several
challenges: First, the abundant use of IoT (Internet of Things) and wearable sensors to diagnose
the disease and record data in the medical record of that patient can increase the risk of attacks.
This could affect the physician’s prescription for the disease and endanger the patient’s life. The
second security issue is fraud detection. There have been many cases where doctors have
prescribed a drug for a patient that is not necessary for him/her just because that certain drug is
available at the hospital’s pharmacy or medical center where the doctor works. As a result, the
patient’s health may be compromised and/or the patient may be forced to bear unnecessary
costs. Another security challenge is counterfeit drugs. Many people die of the use of counterfeit
drugs or suffer from seriousside effects from the use of these drugs. To address this challenge, a
drug supply chain must be put in place in which critical information is accessible. This
information must include the name of the pharmaceutical plant that has manufactured the drug,
then where and how it has been stored; by what distributor it has been transported to the
pharmacy, the distribution date, etc. To overcome the above-mentioned problems, Blockchain
technology can be used. The distributed ledger of Blockchain has a distributable feature so it
reduces the risk of an attack on an integrated center. Moreover, this distributed ledger cannot be
changed and the transactions registered in it cannot be modified. In addition, only the patient
can permit a third party to read or change their data by having their private key and public key.
To do this systematic review, the guidelines proposed in [30,64] were adopted and the existing
Blockchain-based approaches that tried to preserve privacy and security in healthcare are
reviewed. The remaining of the paper is organized as follows. In Section 2, previous review
papers are discussed. Section 3describes the methodology and criteria for selecting the papers.
In Section 4, the advantages and disadvantages of using Blockchain in the field of healthcare are
discussed. The existing Blockchain-based approaches that tried to improve the privacy issue in
healthcare are mentioned in Section 5. The existing Blockchain-based approaches that tried to
improve security issues in healthcare are described in Section 6.InSection7, the reviewed
papers are discussed and analyzed. Section 8describes the open Issues and future research
directions. Section 9is dedicated to the conclusions and limitations of this SLR study.
2 Related work and motivation
In this section, we discuss the related survey and SLR papers that examined the Blockchain-
based privacy and security approaches in healthcare.
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The authors of [23] reviewed 143 papers on the role of Blockchain in healthcare and
discussed the existing challenges in the EHR domain (including power consumption, failure,
and attack points). Blockchain was used to solve these challenges of trustless environments and
secure data exchange. In this paper two platforms were introduced: permissionless Blockchain
(Ethereum) and permissioned Blockchain (Hyperledger) to solve EHR challenges. The authors
reviewed the issues of privacy and security, and compared traditional EHR methods with those
implemented by Blockchain. Finally, the limitations of the methods were mentioned.
In another study [55], 52 papers were reviewed. These papers discussed how Blockchain
technology, along with smart contract systems, can support healthcare applications for physi-
cians, patients, insurance companies, and assets such as patient’s data, medical information,
equipment, and pharmaceutical chains.
The authors of [7] reviewed 31 papers. This paper described how this technology improves
healthcare and prevents diseases and suggested a new protocol to ensure patient privacy and
guarantee confidential data. Secure encryption methods and digital signatures were introduced
to ensure authorized access to shared information using Blockchain. Then, a strong review of
the accuracy of the EHR data was presented.
The authors of [31] reviewed 69 papers. This paper discusses the role of Blockchain in
healthcare. This paper addressed the challenges of system security, interoperability, data sharing,
and mobility in the field of EHR and explained how Blockchain can handle these challenges. Then,
the following platforms were introduced to implement Blockchain in healthcare: Gem Health
Network, OmniPHR, Medrec, Inclusive Social Networking System (PSN), and Virtual Resources.
Another study [54] was a systematic literature review that reviewed 42 papers published
between 2016 and 2019 related to applying Blockchain in healthcare. In this paper, some
challenges such as using Blockchain in healthcare, sharing and processing medical data and
patient records were analyzed. The authors examined the implementation model, limitations,
and costs of using Blockchain in healthcare.
The authors of [52] conducted a systematic review of 62 papers related to Blockchain-based
approaches in healthcare systems published between 2016 and 2020. In this paper, the authors
reviewed the use cases, challenges, and structures of Blockchain-based approaches in healthcare.
Then, the implementation methods, technical cases, and the use of Blockchain in the field of
medicine were evaluated. Finally, future directions and future works in this field were discussed.
The authors of [4] studied 37 papers related to Blockchain-based approaches in healthcare
published between 2017 and 2020. This paper examined how to access medical records,
security, data tracking, and medical information and how to exchange information in the
Blockchain healthcare network. Also in this paper, challenges such as how to register and
accept transactions, how to implement interoperability, regulations, and restrictions related to
medical data in the community, and issues related to scalability and management of access
permissions were mentioned.
The authors of [18] reviewed 39 papers that used Blockchain in healthcare approaches
published between 2018 and 2020. This paper mentioned that using Blockchain can be
effective for data integration, access control, and interoperability. The authors of this paper
believed that using Blockchain in healthcare systems is expanding rapidly and therefore
research in this field can be absolutely vital and useful.
Another study [19] reviewed a total number of 940 papers, and books published between
2016 and 2020 that used Blockchain technology in healthcare. This paper discussed telecare
and the role of security and privacy. In this paper, some issues of using Blockchain in
healthcare such as interoperability, scalability, and storage were discussed.
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In another study [24], 50 papers published on reputable scientific sites between 2015 and
2020 that used Blockchain in healthcare were analyzed. This paper highlighted the role of
quality criteria. First, new trends of using Blockchain in healthcare were introduced, then these
new trends were analyzed, and finally, the challenges of using these new trends were discussed.
This paper also discussed issues such as integrating cloud computing technology and
Blockchain in healthcare.
The authors of [46] reviewed a total of 626 papers published between 2016 and 2020 that
used Blockchain technology in healthcare. In this paper, systematic methods for reviewing
papers were presented. These systematic methods include: relying on scientific methods, the
number of authors of the paper per year, the introduction of the institutions that created the
paper, and the separation of papers based on the country of the author of the paper.
Akbar et al. [5] reviewed 72 articles between 2017 and 2021 on the role of Blockchain in
healthcare. In this research, the fuzzy technique has been used to prioritize and sort the existing
solutions in the field of Blockchain-based healthcare. Also, in this research, new methods have
been used to optimize and create a road map in the field of Blockchain-based healthcare.
Sharma et al. [51] reviewed 47 articles between 2017 and 2021 on the use of Blockchain in
healthcare. In this research, challenges such as optimal use of resources, data integrity, and
rapid development of the healthcare Blockchain have been addressed.
Rahmani et al. [42] reviewed 34 articles between 2016 and 2021 in the field of using
Blockchain in the Internet Medical of Thing (IoMT). In this research, the challenges of trust in
the context of cloud computing for storing Internet of Things data have been discussed.
Blockchain is mentioned as a solution for decentralization and security of data generated by
sensors and wearable devices.
The authors of [48] reviewed 51 articles between 2017 and 2021 on the use of Blockchain in the
field of healthcare. In this research, the major challenges such as lack of integrity, manipulation, and
fraud in medical care data have been identified, and Blockchain has been mentioned as a solution to
overcome these challenges. Also, in this research, the benefits of using the Blockchain in the field
of healthcare are mentioned, such as more efficiency, less delay in information transmission, more
data security, and improved management of resource consumption.
Abbas et al. [1] reviewed 53 articles between 2016 and 2021 on the use of Blockchain
technology in healthcare. In this article, advantages such as non-alteration and manipulation of
healthcare data, anonymity of participating parties, protection of patients’privacy, improve-
ment of drug supply chain management, and safe and fast access to patient’s records in the
healthcare Blockchain are mentioned.
Examining the mentioned papers, several defects are found. For example, some of these
papers are not SLR or the selection process is not clear or the tools used for evaluation and the
framework are not specified in these papers. In this systematic review, we attempted to address
these shortcomings.
Table 1lists survey and SLR papers on healthcare security and privacy using Blockchain in
recent years. In this table, each paper is examined considering the publication year, main topic,
review types, paper selection processes, tools or framework, and covered years.
3Researchmethodology
In this section, a methodology for doing this systematic review is mentioned. A systematic
literature review has several advantages over traditional reviews, including: greater
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Table 1 Summary of the related works
Reference Publication
year
Main topic Review
type
Paper selection
process
Blockchain type Evaluation
metrics
Tools or
Framework
Covered
years
Mohamad Kassab et al. [23] 2019 Analysis of the challenges of using
Blockchain in healthcare for stakeholders
(patients, physicians, healthcare providers,
insurance companies)
Survey Clear Not mentioned Not mentioned Clear 2015–2018
TOQEER ALI SYED et al.
[55]
2019 Analysis of several applications that use
Blockchain in the field of healthcare
Survey Not clear Mentioned Not mentioned Not clear 2015–2018
Susel Góngora Alonso et al.
[7]
2019 An overview of the role of the Blockchain in
healthcare and new ways to share data in
this area
Survey Not clear Not mentioned Not mentioned Not clear 2015–2018
Thomas McGhin et al. [31] 2019 Analysis of challenges such as: security,
interoperability, data sharing in the field of
healthcare using Blockchain
Survey Not clear Not mentioned Mentioned Not clear 2016–2017
Anushree Tandona et al.
[54]
2020 Analysis of processing and sharing and the
patient records and medical data
SLR Clear Mentioned Mentioned Clear 2016–2019
Leili Soltanisehat et al. [52] 2020 Review of the use cases, challenges and
structures of using Blockchain in
healthcare
SLR Clear Mentioned Not mentioned Not clear 2016–2020
Israa Abuelez et al. [4] 2020 Analysis of the challenges of accessing
medical records, security, data tracking
and medical information and how to
exchange information in the Blockchain
healthcare network
Survey Clear Not mentioned Not mentioned Not clear 2017–2020
Anton Hasselgren et al. [18] 2020 Analysis of the challenges of access control,
interoperability, and integrity of medical
data using Blockchain
Survey Not clear Mentioned Not mentioned Not clear 2018–2020
Hassan Mansur
Hussien et al. [19]
2021 Analysis of the challenges of Telcare medical
information system and improving security
and privacy in this area
Survey Clear Mentioned Mentioned Not clear 2016–2020
SABITA KHATRI et al.
[24]
2021 Systematic analysis of Blockchain
aggregation with healthcare
Survey Clear Not mentioned Not mentioned Not clear 2016–2020
2021 Survey Clear Not mentioned Not mentioned Not clear 2016–2020
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Table 1 (continued)
Reference Publication
year
Main topic Review
type
Paper selection
process
Blockchain type Evaluation
metrics
Tools or
Framework
Covered
years
Abderahman Rejeb et al.
[46]
Opportunities and use cases of Blockchain in
healthcare
Akbar et al. [5] 2022 Presenting fuzzy techniques for sorting and
prioritizing existing solutions in the field
of using Blockchain in healthcare.
SLR Clear Mentioned Mentioned Not clear 2017–2021
Sharma et al. [51] Reviewing the challenges such as resource
optimization, data integrity, and rapid
Blockchain-based healthcare development.
SLR Not clear Mentioned Not mentioned Clear 2017–2021
Rahmani et al. [42] 2022 Systematic analysis of the Blockchain-based
Internet Medical of Things in cloud com-
puting
SLR Clear Not mentioned Not mentioned Not Clear 2016–2021
Saeed et al. [48] 2022 Analysis of the Challenges such as lack of
integrity of data, manipulation and fraud in
medical data, and delay in transmission of
healthcare data
Survey Clear Mentioned Mentioned Not Clear 2016–2021
Abbas et al. [1] 2022 Systematic analysis of the Blockchain-based
solutions for data sharing and supporting
the anonymity of participating parties in
the healthcare network.
SLR Clear Mentioned Not mentioned Not clear 2016–2021
This work - Analysis of the approaches for Improving
healthcare security and privacy using
Blockchain
SLR Clear Mentioned Mentioned Clear 2018–2022
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transparency, more accurate reviews, step-by-step analyses, and more regular reviews. The
article selection process and the research questions are also explained in this section.
3.1 Question formalization
The research questions that are answered in this study are as follows:
RQ1: What are the advantages and disadvantages of using Blockchain in Healthcare?
RQ2: How the patient’s privacy in EHR is guaranteed by Blockchain?
RQ3: How the patient’s security in EHR is guaranteed by Blockchain?
RQ4: What evaluation metrics are applied for evaluating the Blockchain-based ap-
proaches for improving security and privacy in healthcare?
RQ5: What are the tools or frameworks used in the Blockchain-based approaches for
improving security and privacy in healthcare?
RQ6: What kind of Blockchain was used in the existing research studies?
RQ7: What are the open issues and future research directions of using Blockchain for
improving the privacy and security of healthcare?
3.2 Paper selection process
Figure 1summarizes the papers selection process in three steps:
Step 1: At this step, the papers are selected based on the title, abstract and keywords. 487
papers were selected at the end of this step.
Step 2: At this step, the continuation of the selection process of papers has been carried out
based on the inclusion and exclusion criteria given in Table 3.Attheendofthisstep,
331 papers were remained.
Step 3: Finally, by studying the full text of the papers and removing inappropriate ones, 51
papers were remained as final selected papers to be reviewed in this systematic
review.
This study reviews papers published between 2018 and August 2022 that focused on
Blockchain-based approaches for improving security and privacy in healthcare. Various
databases have been used to conduct this study. The URLs of the used database are listed in
Table 2.
Fig. 1 Paper selection process
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The search keywords for the papers were as follows:
“Blockchain”AND (“Healthcare”OR “EHR”OR “Medicine”OR “Electronic Health
Record”)
Table 3lists the criteria for including and excluding the papers.
After applying the above keywords, 331 journal papers and 156 conference papers were
found at the end of step 1. The number and percentage of journal and conference papers are
shown in Fig. 2.
Figure 3illustrates the number and percentage of final papers selected from each database.
Figure 4shows the number of final papers selected at the end of step 3 categorized by years.
4 Advantages and disadvantages of using Blockchain in healthcare
In this section, we try to answer RQ1: What are the advantages and disadvantages of using
Blockchain in Healthcare?
Using Blockchain technology can improve the integrity, privacy, and security and it
provides better access to the necessary services. With Blockchain technology, both specialists
and health organizations can act faster and more efficiently based on the available information
Table 3 Inclusion/exclusion criteria
Criteria Description
Inclusion
Studies that focused on Blockchain-based approaches for
improving security and privacy in healthcare
Journal papers published online from 2018 to August 2022
These papers are exactly fit for this study
These papers have a high scientific value
Exclusion
Thesis, books, or book chapters
Review papers or papers that only interpret the role of the
Blockchain in healthcare
Not English papers or unjudged papers
This group of resources does not fit into our
selection criteria.
The intended solution in these papers is not clear
Because these papers have not been fully judged
and evaluated, they are not selected
Table 2 The searched online databases
Online database URL address
Google Scholar www.Scholar.google.com
IEEE www.ieeexplore.ieee.org
ACM www.dl.acm.org
Science Direct www.sciencedirect.com
Springer www.link.springer.com
Taylor & Francis www.tandfonline.com
Wiley www.onlinelibrary.wiley.com
Inderscience www.inderscienceonline.com
ACM www.dl.acm.org
Sage www.online.sagepub.com
Emerald www.emeraldinsight.com
Wiley https://onlinelibrary.wiley.com
MDPI www.mdpi.com
Hindawi www.hindawi.com
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which is safe and reliable. A safe and effective infrastructure can be created using smart
contracts to increase the quality of healthcare and improve the well-being of individuals.
The authors of [47] presented the creation of the prototype and evaluation of the OmniPHR
architectural model. A Personal Health Record (PHR) is a file that allows patients to access
and manage their data. The OmniPHR integrates the Blockchain distributed records and
OpenEHR. The performance of the OmniPHR was evaluated by dividing it into workloads
and simultaneous sessions to transfer the database to a network of ten clouds. The results of the
experimental evaluations in this paper showed that the Blockchain architecture of OmniPHR
provides high-quality performance at the network level.
In another study [66], some applications of Blockchain in healthcare domains were
presented as follows: (1) Track prescriptions to detect drug overdoses. (2) Sharing data for
Fig. 3 The number and percentage of final papers selected from each database
Fig. 2 Total selected papers at the end of step 1
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integrating traditional care into telemedicine. (3) Sharing data with the provider so that the
patient can specify what data is being authorized. (4) Sharing the registered cases of cancer;
collecting all of the observed cases of cancer. (5) Managing the patient’s digital identity to
better match the patient’s history. (6) Creating a personal health record that can be fully
accessed and controlled. (7) Automation of health insurance claims for error detection and
fraud. This paper also discusses the challenges of using the Blockchain in healthcare, such as
system evolution, privacy protection, etc.
Another study [29] mentioned some healthcare projects that benefit from Blockchain
technology. One of the projects worth mentioning here is PokitDok. With PokitDok, organi-
zations related to healthcare can implement modern business in Blockchain and a secure
network of electronic health records and pharmaceutical equipment is provided.
In another study [60], a Blockchain-based security model was presented for electronic
health records called EMRSB. In this model, medical data can be shared safely and effectively.
By using Blockchain technology in EMRSB, Data loss and manipulation problems can be
easily solved. Large files are stored in the IPFS file system
1
and the hash file is added to the
Blockchain, which saves important resources in the Blockchain. This can increase the security
level of the patient’s privacy information.
The authors of paper [27] believed that the decentralization of the Blockchain would
safeguard healthcare data and preserve the privacy of stakeholders in the field. Another
important point mentioned in this paper is the lower cost of transferring data in the Blockchain
compared to traditional methods. Data transfer in the Blockchain is done without the use of a
central entity, which makes it less costly. It also uses Blockchain data tracking to ensure that
healthcare data comes from a reliable source.
In another study [34] the characteristics of data integration and the immutability of data in
the Blockchain were mentioned, which makes the Blockchain a suitable platform for main-
taining healthcare data. In the healthcare network implemented by the Blockchain, the data
added to the ledger cannot be changed and manipulated. The decentralization of the
Blockchain means that there is no single failure point for the healthcare network. The paper
also referred to smart contracts that allow transactions and agreements to be drawn up between
parties involved in the healthcare Blockchain network without third-party intervention.
1
The InterPlanetary File System.
Fig. 4 The number of selected papers at the end of step 3 categorized by years
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Another study [62] listed several advantages of using Blockchain in healthcare, including:
1- Data accuracy in healthcare applications: Storing all healthcare data in the Blockchain
makes this accompanying information up-to-date, traceable, and non-manipulative. These
capabilities help medical professionals improve the treatment process of patients. 2- Interop-
erability of healthcare data: By using interoperability in the Blockchain network, the exchange
of information between stakeholders in this field becomes better because all data in the
Blockchain follow a certain standard, so the exchange of information is more efficient. 3-
Data security in the field of healthcare: Capabilities such as hashing and data immutability in
the Blockchain network make data healthcare more secure. 4- Lower cost of healthcare data
management: The cost of data management in traditional healthcare data systems is much
higher than storing these data seamlessly in a Blockchain network because the information is
stored in different centers and databases. 5- Global sharing of healthcare data: A patient may
be treated in one country and then travel to another to continue treatment. In this case, if
traditional medical care systems are used, sharing patient’s data among several different
countries will be very difficult and perhaps impossible. Using a Blockchain network, patient’s
data can be easily shared globally. 6- Improving the audit of healthcare data using Blockchain:
Using data audits in healthcare ensures that laws and regulations are fully complied with by
institutions and stakeholders in this field. As data in the Blockchain is verifiable and infor-
mation in the Blockchain is non-manipulative, it improves the audit of healthcare data.
The authors of [33] believed that wearable devices and patient-connected sensors play an
important role in modern healthcare systems. In this paper, the data generated from these
devices are integrated with Blockchain technology. This integration plays an important role in
maintaining the security of this data.
The authors of [59] dealt with parallel healthcare systems (PHSs) and the role of
Blockchain in maintaining data security of these systems. This paper proposed a method in
which Blockchain is combined with PHS and using a consortium, healthcare data is shared
more effectively.
Another study [20] pointed out some of the challenges in using Blockchain in healthcare,
including high energy consumption, inefficient scalability, and relatively low throughput. To
address these challenges, this paper introduced an architecture called lightweight Blockchain.
In a lightweight Blockchain network, nodes were distributed in several clusters and a ledger
was maintained in each cluster. This reduced the computational and communication costs of
the healthcare network.
In [53], the attribute-based signature scheme was introduced to further protect the privacy
of medical stakeholders. In this design, keys called master key to authenticate users and update
key to specify attributes related to certain nodes were introduced. In this scheme, a number of
parties participating in the Blockchain network (such as physicians) were identified with
certain characteristics (such as < Hospital A. Department of Oncology. senior Physician>.
After analyzing the patient information, these attributes are taken away from them by an
algorithm called KUNodes.
Jeet et al. [21] developed a Blockchain-based framework for IoT data. In this framework,
patient’s data were collected by sensors and wearable devices, and were updated every
moment. Therefore, new symptoms of illness and sensitivity in response to drugs can be
recorded in the Blockchain immediately. Sha-256 encryption was used in this framework and
the techniques used in this research reduce the encryption time.
Rajasekaran and Azees [43] presented a scheme for authentication of participating parties in
the healthcare Blockchain. This scheme is a lightweight authentication scheme that supports
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the anonymity of participating parties in the healthcare Blockchain. In this scheme, doctors
given the opportunity to share information about patients with other doctors without
compromising the privacy and security of patient’s data. Using the authentication method of
this scheme, only authorized users can view the data of the healthcare field.
The authors of [69] presented a scheme for secure storage and sharing of medical data
based on Blockchain. In this research, the authentication of all parties involved in the
healthcare system has been carefully examined and a solution to the problem of information
dispersion in the healthcare field has been provided.
5 Privacy in healthcare using the Blockchain
In this section, we try to answer RQ2: How the patient’s privacy in EHR is guaranteed by
Blockchain?
Blockchain technology can create a balance between the privacy of health data and access
to those data. The purpose of the privacy policy is to protect patients’privacy while disclosing
PHI
2
. Four goals must be achieved here: 1- Giving t full control of EHRs to patients. 2-
Determining who can access and track the documents. 3- Making possible the secure transfer
of the records. 4- Minimizing the chance of unauthorized people obtaining PHI. Blockchain
technology can help achieve these four goals.
In [12], the authors recommended an efficient and secure Blockchain-based framework for
accessing medical records called Ancile. Smart contracts in this framework were used for
controlling and preventing data misuse. In addition, for improving security, advanced encryp-
tion techniques were applied. The purpose of this paper is to address privacy and security
issues in healthcare. This framework focused on the rights of patient’s data ownership. Data
ownership is held by the patient, while parental or caregiver control is provided.
Paper [63] mentioned that in modern healthcare systems, patient participation is an
important matter. This paper discussed Blockchain-based location sharing for E-health sys-
tems. The first step defines the basic needs for Blockchain-based location sharing, including
decentralization, privacy, and reliability. Then, using Merkel’s cryptography and root, a
Blockchain-based privacy-preserving scheme called BMPLS was proposed for Location
Sharing
3
. The results showed that this plan meets the necessary requirements. Finally, the
outputs of this project and the results of the analysis confirm that this project is useful and
feasible for the field of medical care. In short, the scheme could be used to share telecare
Blockchain-based privacy for medical information systems.
In another study [66], Healthchain, a large-scale Blockchain-based health data privacy
project was presented, in which health data were encrypted to control micro-access. With the
introduction of the Healthchain, IoT data and physician diagnoses cannot be deleted or
manipulated. Security analysis and experimental results suggest that Healthchain’sproposal
applies to the smart healthcare system. The important points mentioned in this paper are as
follows: 1- A Blockchain-based healthcare system is recommended to protect the privacy of
large-scale health data, called a Healthchain. The Healthchain allows users to download IoT
data and receive feedback from physicians. Physicians are then able to read data and upload
feedbacks. 2- In the Healthchain, for reducing the computational overhead and ensuring
2
Personal Health Information.
3
Blockchain-Based Multi-level Privacy-Preserving Location Sharing.
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privacy, data is encrypted and stored in the IPFS
4
. 3- In addition, by transferring updated
transactions, Healthchain allows users to revoke physicians’access at any time.
In another study [39], a Blockchain-based data storage scheme in healthcare was proposed.
The proposed scheme can help improve privacy. Encryption techniques were used to protect
patient’s data and alias. In this approach, data processing methods as well as the cost-
effectiveness of smart contracts used in the system were analyzed. Patients and health
organizations participate as data transmitters and data receivers. With the assistance of these
EHR systems and storing data in cloud network, patients share their personal data with
physicians and health organizations.
The authors of [50] proposed a plan for implementation of EHR, which would protect EHR
data more securely and privately. In this design, a framework was introduced that used the
Hyperledger Fabric Blockchain.
In the proposed platform in [40], many problems are solved by storing encrypted health
information in the cloud system. This platform ensures that patient’s data in the cloud
environment is controlled only by the patient himself. The goal is to maintain important
healthcare data for network integrity and security. Current health systems do not have a
pseudonym because they only store data in the cloud environment. But the proposed platform
guarantees patients’aliases. Acquired aliases are obtained using cryptographic functions.
The proposed approach in [15] used four technologies that could be used in Blockchain for
improving privacy. These four technologies are: zero-knowledge proofs, trusted execution
environments, homomorphic encryption, and federal learning. In zero-knowledge proofs, one
party involved (the prover) is allowed to validate a transaction or validation for the other party
(the verifier) without disclosing any critical information. In healthcare contexts, for example,
how a patient is treated can be expressed without disclosing the patient’s true identity. In
federal learning, an algorithm is sent to a node, then that node analyzes the algorithm and
finally shares the updated algorithm among all the nodes in the Blockchain. In this way, by
separating how to update the algorithm from other nodes, the risks of privacy and security
breaches are minimized. Homomorphic encryption allows calculations to be performed on
encrypted data. For example, a patient can encrypt their data and send it to an unreliable third
party. This third party performs an analysis on the encrypted data and then sends the result of
its analysis to the patient in an encrypted form. In this way, the patient can utilize another
person’s review of their data without exposing his/her data. In trusted execution environment
technology, privacy is met through hardware. Most cell phones today use this technology in
their structure.
In [44], Blockchain-based knapsack algorithms were used for privacy. The greedy algo-
rithm of knapsack can lead to Blockchain-based privacy and security in healthcare. In this
method, first the healthcare data is encrypted by the knapsack algorithm and then this
encrypted data is transferred to the Blockchain. In the Blockchain, healthcare data is validated
and then decrypted by the knapsack algorithm and finally sent to the desired nodes. Knapsack
algorithms are symmetric cryptographic systems. This method uses public keys to encrypt and
private keys to decrypt.
Paper [32] suggested a framework that uses off-chain computing and storage technology.
Off-chain Blockchain hybrid design architecture (OCBS) processes and manages information
through distributed software that interacts with off-chain sources. This system tries to improve
privacy and scalability. In the framework proposed in this paper, the ownership rights of
4
Inter-Planetary File System.
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patient’s data are observed. Moreover, in this framework, patients can manage their own data
and digital identity.
Paper [67] proposed a Blockchain-based telephone privacy tracking plan in the field of
healthcare. In this plan, healthcare stakeholders can connect to the Blockchain network with
their mobile phones. In this plan, first, the location of the caller is determined and then it is
determined whether a particular patient has called this system. In the design proposed in this
paper, the integration of emerging 5G technology with Blockchain-based healthcare systems
leads to higher reliability, less communication delay and improved privacy of medical
stakeholders.
Another study [58] pointed to the role of Blockchain technology in better management of
healthcare data and maintaining the security of this data. In this paper, a prototype using the
Hyperledger platform was proposed. This prototype was an authorized private Blockchain that
ensures better control of access to healthcare data.
The paper [3] proposed a reliable framework for wearable devices and patient-connected
sensors that utilized Blockchain technology. With data management, this framework protected
the privacy of information related to the field of healthcare and ensured the confidentiality and
integrity of data.
The authors of [25] introduced a framework that uses Blockchain technology. Using smart
contracts, this framework provided effective management to conserve human resources. In this
framework, the human resource data were created and then these data were distributed on a
global platform based on Blockchain.
In another study [65], fuzzy analytic on the blockchain platform was introduced. Using
fuzzy analytic network, a Blockchain implementation model to improve the security of
healthcare data was introduced. In this study, a permissioned private Blockchain network
was used to manage access to medical data.
A decentralized architecture based on Blockchain was proposed by Nishi et al. [38]. In this
architecture, the patient is the real owner of his/her data, in such a way that any permission to
view the data related to the patient must be done with his/her permission. In this architecture,
attribute authorities can issue or revoke the attribute only with the patient’spermission.
Alsayegh et al. [8] investigated how the privacy and security of EHR sharing can be
maintained in two types of Blockchain networks. Private Blockchain was used to store
encrypted EHRs and consortium Blockchain along with smart contracts to verify the identity
of patients.
The authors of [2] introduced a framework for greater security and privacy of individuals
who received the Covid-19 vaccine using Blockchain. In this framework, the W3C standard
certificate is used to prove the certificate of receiving the vaccine. In this framework, IPFS has
also been used to protect the privacy of vaccine recipients. In this framework, users have been
given the opportunity to share their data with other people without compromising their security
and privacy.
6 Securing healthcare data by using the Blockchain
In this section, we try to answer RQ3: How the patient’s security in EHR is guaranteed by
Blockchain?
In the smart health scenario, one of the most important issues is the security of the health
system. The main challenges for a smart health system are security and the reduction of
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accurate data with the rule. Blockchain technology suggests that a consortium shall consist of
several stakeholders such as hospitals, physicians, pharmacists, pathologists, researchers, and
insurance companies. The security debate here means the secure exchange of data among all
the parties involved. Moreover, all the stakeholders must be authenticated and authorized to
enter each level of the Blockchain.
The authors of [26] stated that Blockchain may provide a solution to address current EHR
performance limitations. In Blockchain, the patient’s entire record is stored in the ledger and
encrypted by the patient’s private key. Although the Blockchain system is not completely
impenetrable, it is more secure than most current systems.
The authors of [11] suggested that data theft in the EHR can endanger patient privacy. In
general, most data in the EHR remains unchanged after being uploaded to the system.
Therefore, Blockchain can be used to share this data more effectively. Participating organiza-
tions and medical parties can more confidently access EHRs stored in Blockchain. In this
paper, a cryptographic scheme for healthcare was proposed based on Blockchain technology.
The index for the EHR is stored in the Blockchain. Because only this index is transferred to
Blockchain for ease of publication, patients have complete control over who can view their
EHR data. In this system, only search indices are added to the Blockchain and facilitate EHR
distribution, while real EHRs are stored encrypted on another server. To access EHRs, users
must grant their permission to the information owner with a decryption key.
Paper [36] presented a new EHR sharing scheme based on cloud computing and
Blockchain. Initially, the authors identified the main challenges of current health systems,
and effective solutions to these problems are proposed through the implementation of a real
prototype. To test the proposed method, an Amazon-based Ethereum Blockchain is proposed.
Moreover, to achieve data storage and data sharing, the IPFS storage system integrates with
Blockchain. The results of this program showed that the proposed framework can share
medical information more safely and quickly compared to conventional methods. By using
access control, unauthorized access to health data can be detected and prevented. The
advantages of the proposed model showed that the Blockchain solution is a more effective
way to manage medical records compared to traditional methods.
Paper [28] addressed the problems of data collaboration and the use of healthcare programs
in a heterogeneous cloud environment. A framework called ChainSDI suggests that the
Blockchain technique, along with many computational resources, may be used to manage
secure data. The prototype shows how this framework works.
The proposed method in [10] had the following architecture contributions: First, a
healthcare framework called ChainSDI is presented which is based on a combined “home-
edge-core”SDI to provide real-time performance and accountability for home-based
healthcare services. Second, they are looking to build a secure Blockchain network to ensure
that any transaction in ChainSDI is in accordance with the regulations, while still being able to
interact with the data.
Paper [17] provided telemedicine services on demand (MoD). This technology is used to
overcome challenges and improve telemedicine services. This paper proposed an approach to
achieve authentication and licensing with greater flexibility and efficiency for the department
of defense’s services in the medical trap system. A key program has been distributed for
independent updates in the telemedicine system, which aims to update the patient’skeys
separately. Using Blockchain and distributed ledger also protects the integrity of private
healthcare data. This prevents malicious users from trying to change the physicians’diagnosis.
Using the Blockchain technique in EHR, patient’s data is stored in a chain to prevent a user or
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unauthorized users from manipulating it. Finally, it is concluded that the proposed approach
resists collusion attacks in (N-1) destructive attacks.
In [22], containers in the Blockchain substrate were used for greater security of healthcare
data. These containers are connected to multiple ports to improve the data transfer process. In
this research, a framework called Medichain on a Blockchain platform is proposed. In each
block of the proposed framework, a list of patient records is maintained, which is secured using
the security features of Blockchain technology. This framework was implemented by the
Python programming language and used object-oriented concepts.
The authors of [61] used Blockchain technology to further secure healthcare data. The
scheme proposed in this paper places great emphasis on protecting patients’medical records
from information theft and unauthorized intrusion. This paper first identified how to manage
and control access to medical care data. Then, using Blockchain technology, a platform for
data storage and transmission was introduced. In this platform, data transfer and storage were
done through cryptographic algorithms. The results of the implementation and simulation of
the proposed platform showed better performance in data storage as well as more efficient data
transfer than similar schemes.
The authors of [68] emphasized the privacy and security issues of healthcare stakeholders.
In this paper, several features of Blockchain technology such as: anonymous signatures, zero-
knowledge proofs, attribute-based encryption, and approval of smart contracts were used for
more security of healthcare data. This paper also used various security techniques to ensure the
data sharing process.
In another study [45], the characteristics of the Blockchain network were investigated.
Then, consensus algorithms were analyzed, and finally, a framework for maintaining the
security and privacy of data related to patients in the field of healthcare was introduced.
The authors of [57] discussed remote patient monitoring (RPM). In this paper, an archi-
tecture was presented that effectively transfers healthcare data and stores them in a Blockchain.
In another study [14], Blockchain’s smart contracts were used for the proper analysis and
management of data generated in the field of medical care. Using the method presented in this
paper, the generated data by sensors connected to the patient’s body are analyzed by smart
contracts. If the patient-generated data were in critical condition, a warning was sent to the
medical center so that the patient could receive immediate intensive care.
In [13], a Blockchain-based healthcare data management system was proposed. Using this
information management system, patients can easily access their medical records located in
various medical centers. Asymmetric encryption was used to further secure the system data.
The authors of [56] integrated smart health care systems (SHSs) with Blockchain technol-
ogy. This paper examined the challenges of SHS systems and used Blockchain technology to
maintain greater security and data integrity in the field of smart healthcare.
Another study [16] presented an attribute-based signature scheme with different authorities.
In this paper, the patient disclosed part of his data without exposing the rest of his information.
This part of the information disclosed by the patient is provided to physicians and researchers
by healthcare providers. The physician or researcher performs the desired analysis on this data.
At the end, these authorities were taken away from them.
The authors of [41] proposed solutions to prevent the production and distribution of
counterfeit drugs in the healthcare network using Blockchain technology. This plan
covers the drug distribution cycle from production to consumption by the patient. The
distribution and production of counterfeit drugs in the healthcare system is prevented by
using Blockchain.
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Paper [35] dealt with the safe storing of healthcare data. It provided a Blockchain-based
framework using a keyless signature protocol for the security of patient’s medical records and
ensured the integrity and security of data in this area.
Another study [49] introduced a framework based on Blockchain. In this framework, the
management and control of access to medical data were effectively proposed. The use of this
framework improved data privacy, confidentiality, and decentralization in the medical care
system.
Qadar Butt et al. [9] presented a Blockchain technology for use in medical communication
and developed a location-independent global health record exchange system for transferring
medical data. Using Blockchain technology and a federal identity management system, the
proposed system authenticates users and the person requiring user information under the
guidance.
The authors of [37] presented a scheme for sharing data in the field of healthcare using
Blockchain and edge computing. This scheme guarantees the security and privacy of shared
data. In this scheme, the hash and filtering functions were used to maintain the security of the
shared data. Also, in this research, a process has been designed to determine the amount of
reward for miners to mine healthcare blocks.
In [6], Blockchain was used to access keywords for searching in distributed healthcare
databases and a new mechanisms are used to revoke the public and private keys of users.
Therefore, any user will not be able to access the healthcare blockchain after a certain period of
time. This makes the healthcare Blockchain more secure. In the proposed approach, public and
private keys are given to the participating parties only for a certain period of time to prevent
unauthorized people from entering the healthcare Blockchain.
7Discussion
This section analyzes the reviewed papers to answer the remaining research questions:
RQ4: What evaluation metrics are applied for evaluating the Blockchain-based
approaches for improving security and privacy in healthcare?
Table 4lists the evaluation metrics for assessing the Blockchain-based approaches for
improving security and privacy in healthcare. Evaluation metrics such as integrity (in 10%
of papers), access control (in 8% of papers), security (in 25% of papers), privacy (in 17% of
papers), availability (in 6% of papers), latency (in 4% of papers), scalability (in 10% of
papers), performance (in 17% of papers) and cost (in 4% of papers) were reviewed and
analyzed. Figure 5represents the percentage of using each evaluation metrics considered in
the selected papers.
RQ5: What are the tools or frameworks used in the Blockchain-based approaches for
improving security and privacy in healthcare?
Table 4lists the tools and frameworks used in the existing Blockchain-based approaches for
improving security and privacy in healthcare. Various frameworks, platforms and tools have
been used in the papers reviewed in this review paper. These frameworks, platforms and tools
have various features, the most important of which are: Use of smart contracts to control access
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Table 4 A summary of the reviewed papers
Reference Main idea Kind of Blockchain Tool(s) or framework(s) Evaluation metrics
Roehrs et al. [47] Creation of the prototype and evaluation of the
OmniPHR architectural model
Private A method called
OmniPHR
MTBF, MTTR
Peng Zhang et al. [66] Several practical applications of Blockchain in
healthcare
Both(public and private) Not mentioned Not mentioned
Jorge Lopes et al. [29] A safe way to improve the security and privacy of
healthcare
Not clear Not mentioned Not mentioned
Sihua Wu, Jiang Du [60] A secure model for Blockchain-based healthcare data
sharing
Not clear Not mentioned Not mentioned
Tian-Fu Lee et al. [27] A plan for telecare of healthcare information using
Blockchain
Private Not mentioned Security, Performance,
efficient computation and
communication.
AHMAD MUSAMIH et al. [34] Tracking of medical data in Blockchain-based
healthcare network
Public Not mentioned Cost, Security, Scalability
Ibrar Yaqoob et al. [62] Projects and case studies to demonstrate Blockchain
performance in various healthcare applications
Both(public and private) Not mentioned Not mentioned
Mulalo Muofhe et al. [33] Manage and control patient’s data in healthcare
systems using Blockchain
Not clear Not mentioned Not mentioned
Wang et al. [59] Create an artificial model of electronic health records
to simulate and display real data Blockchain-based
healthcare systems
Consortium A framework c alled PHS integrity, interoperability and
facilitating medical research
Leila Ismail et al. [20] Secure transfer of transactions and confidential data
between nodes participating in a Blockchain-based
healthcare network
Public Not mentioned Security, Privacy,
Performance
QIANQIAN SU et al. [53] A revocable signature-based scheme for healthcare
data using Blockchain
Private Proposed a revocable
signature framework
Security, Privacy,
Performance
Rubal Jeet et al. [21] Using the Blockchain to prove the receipt of the
Covid-19 vaccine
Public A framework for the
security and privacy of
people receiving the
Covid-19 vaccine
Scalability, Data integrity
Arun Sekar Rajasekaran And M.
Azees [43]
Providing a lightweight scheme to support the
anonymity of participating parties in the healthcare
Blockchain
Public Not mentioned Communication Cost
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Table 4 (continued)
Reference Main idea Kind of Blockchain Tool(s) or framework(s) Evaluation metrics
Duo Zhang et al. [69] A scheme for secure storage and sharing of medical
data based on Blockchain
Consortium Blockchain A framework for
authentication,
uploading and
updating data
Access Control, Integrity,
Auditability
Dagher et al. [12] Control the level of access to healthcare data using
Blockchain
Private A framework called
Ancile
Recognize the difficulty of
accessing healthcare data
Ji et al. [63] Blockchain-based privacy for Telecare medical
information systems
Hybrid A Blockchain-based
multi-level location
sharing scheme
(BMPLS)
initialization, location record,
and location sharing
Al Omar et al. [39] Propose a platform for Blockchain-based healthcare
stakeholder data privacy
Hybrid A platform called
MediBchain
Pseudonymity, privacy,
integrity, accountability
and security
Yogesh Sharma, Balamurugan [50] Propose a Blockchain-based system for improving the
privacy and security of healthcare data
Private Framework based on
Hyper Ledger Fabric
Not mentioned
Prateek Pandey, Ratnesh Litoriya
[40]
Propose a plan for the global implementation of
Blockchain-based health services
Public Not mentioned Not mentioned
Marielle Gross, Robert C. Miller
[15]
Use four Blockchain-based technologies to protect
healthcare data
Not clear Not mentioned Not mentioned
Ranjith J, Mahantesh K [44] Blockchain-based Knapsack algorithms for privacy Not clear Knapsack crypto‑system Execution time, Block
generation time
Ken Miyachi, Tim K. Mackey [32] suggest a framework that uses off-chain computing
and storage technology
Consortium A framework that uses
off-chain computing
and storage technology
Performance,
Can Zhang et al. [67] proposes a Blockchain-based telephone privacy track-
ing plan in the field of healthcare
Both(public and private) Not mentioned Computational costs,
communication costs
Muhammad Usmana, Usman
Qamar [58]
Improved access control and medical data sharing Not clear Mentioned Not mentioned
ABOU-NASSAR et al. [3] Models to make healthcare data more secure using
Blockchain
Private A framework called
DITrust Chain
Scalability, mutual
authentication,
trustworthiness, privacy,
data integrity and
availability
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Table 4 (continued)
Reference Main idea Kind of Blockchain Tool(s) or framework(s) Evaluation metrics
KIM et al. [25] Propose a framework for maintaining the privacy of
health record management
Hybrid Not mentioned latency and failure point
Zarour et al. [65] Evaluate the Blockchain-based approach to improve
the security of healthcare records
Private Not mentioned Patient’s identity, data
security, data monitoring
and immutability
Farjana Khanam Nishi [38] A decentralized architecture based on Blockchain Public An Ethereum framework
for decentralized data
sharing
Not mentioned
Muneera Alsayegh et al. [8] A decentralized Blockchain-based architecture for
encrypted data storage and patient identification
Consortium- Private An Ethereum framework efficiency
Amal Abid et al. [2] A framework for more security and privacy of persons
who receiving the Covid-19 vaccine
Private A framework for secure
data sharing of people
who receiving the
Covid-19 vaccine
Scalability, Cost
Nir Kshetri [26] Cyberattacks against healthcare data Not clear Not mentioned Not mentioned
Chen et al. [11] Searchable encryption for encrypting healthcare data
using Blockchain
Hybrid EHRs sharing scheme system security and privacy
NGUYEN et al. [36] Mobile and cloud-based healthcare data sharing using
Blockchain
Hybrid A Blockchain-based
searchable encryption
framework
Access control, network
latency, flexibility,
availability, single point
of failure and integrity
Li et al. [28] Proposeaplantoimplementhealthcare data software
infrastructure in accordance with the rules using
Blockchain
Private A framework called
ChainSDI
Threat model and security
analysis, Blockchain
performance analysis and
service performance
analysis
Sabyasachi Chakraborty et al. [10] Create a framework for managing, controlling and
storing patient’sdata
Consortium A framework for
managing, controlling
and storing patient’s
data
Not mentioned
GUO et al. [17] Aneffectiveandflexible model for implementing a
telemedicine system using Blockchain
Hybrid Not mentioned authority, traceability and
integrity
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Table 4 (continued)
Reference Main idea Kind of Blockchain Tool(s) or framework(s) Evaluation metrics
Rahul Johari et al. [22] Improve the security of healthcare data using
Blockchain
Not clear A framework called
Medichain to secure
patient’sdata
Not mentioned
HONGJIAO WU et al. [61] The scheme proposed in this paper places great
emphasis on protecting patients’medical records
from theft of information and unauthorized
intrusion.
Not Clear Not mentioned Security, Performance
Rui Zhang et al. [68] Several features of Blockchain technology such as:
anonymous signatures, zero-knowledge proofs,
attribute-based encryption and approval of smart
contracts were used for more security of healthcare
data.
Private Not mentioned Not mentioned
Partha Pratim Ray et al. [45] Use Blockchain to improve the security of data
generated by sensors and wearable devices
Not Clear Not mentioned Not mentioned
ASHRAF UDDIN et al. [57] Improve data sharing among healthcare stakeholders Private Not mentioned Privacy, Security,
Performance
Kristen N. Griggs et al. [14] Use smart contracts to monitor patient’s data Private Not mentioned Security, Privacy
Kai Fan et al. [13] Improve the management and sharing of healthcare
data
Both(public and private) Not mentioned Privacy, Security,
Performance
Gautami Tripathi et al. [56] Intelligent healthcare systems using Blockchain Not mentioned A framework based on
intelligent healthcare
systems
Not mentioned
RUI GUO et al. [16] Attribute-based signature model Not mentioned Not mentioned Privacy, Security
Prateek Pandey, Ratnesh Litoriya
[41]
Prevent the distribution of counterfeit drugs using
Blockchain-based networks
Private Hyperledger framework Transparency, Privacy,
Security
Gayathri Nagasubramanian et al.
[35]
Improve the integrity of healthcare data Not mentioned Keyless signature
infrastructure frame-
work
Integrity
AYESHA SHAHNAZ et al. [49] Secure storage of healthcare data in compliance with
the rules and regulations of medical organizations
Public A framework for secure
storage of healthcare
data
Latency, Integrity, Access
control
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Table 4 (continued)
Reference Main idea Kind of Blockchain Tool(s) or framework(s) Evaluation metrics
Ghulam Qadar Butt et al. [9] A Blockchain technology for use in medical
communication and developed a
location-independent global health record exchange
system for transferring medical data
Private Hyperledger Fabric
framework
Latency
Xueli Nie et al. [37] A blueprint for healthcare data sharing using
Blockchain and edge computing
Public A framework for IoMT
edge computing and
more security and
privacy of IoMT data
Latency, Cost
Aitizaz Ali et al. [6] Using Blockchain for faster keyword searching in
healthcare distributed databases
Public A framework for the
privacy-preserving in
IoT
Not mentioned
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and protection of data, guaranteeing access to data and ensuring that the patient owns the
information about himself/herself, protection of data generated by sensors and wearable
devices, distribution of data globally and Internationally, artificial intelligence decision making
for better disease diagnosis, searchable encryption for sharing medical records, secure man-
agement of healthcare data, telemedicine services, etc.
RQ6: What kind of Blockchain was used in the existing research studies?
Table 4lists the types of Blockchains used in each paper. Figure 6represents the percentage of
the Blockchain’s type, used in each reviewed paper. 35% of the reviewed papers used private
Blockchain, 10% used hybrid Blockchain, 43% used public Blockchain, and 12% used
consortium Blockchain.
Fig. 5 The percentage of using each evaluation metric considered in the selected papers
Fig. 6 The percentage of Blockchain’s type used in the reviewed papers
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8 Open issues and future research directions
In this section, we aim to answer RQ7: What are the open issues and future research directions
of using Blockchain for improving the privacy and security of healthcare?
Some issues of using Blockchain in Healthcare such as cost, profitability, and scalability require
further research. Using a distributed system for eliminating intermediaries can effectively over-
come many of the current challenges in the medical and healthcare systems. Moreover, despite the
existence of a pandemic such as Corona (Covid-19), the creation of a Blockchain network, which
is a consortium of all the parties involved in the disease, could be the subject of future research.
Using this Blockchain consortium network, various medical centers, governments, patients,
insurance companies, information centers, etc. can exchange all information about epidemics.
Therefore, by using this safe platform, all treatment methods as well as accurate statistics of
epidemic diseases, can be obtained. Some other important open issues and future works are:
&Pharmacy: The use of Blockchain in the pharmaceutical industry improves the tracking of
products in this area and prevents the distribution of counterfeit drugs.
&Globalization of healthcare networks: Blockchain-based healthcare networks can be im-
plemented globally. Using global healthcare networks, patients’medical records can be
accessed from anywhere in the world.
&Improving the scalability of Blockchain-based healthcare: Due to the increasing use of
Blockchain technology in healthcare networks, more research is needed to improve the
scalability of these networks.
&Use more efficient cryptographic techniques: Healthcare transactions contain critical
information that is considered by many hackers and attackers. Therefore, the development
of new and more effective encryption methods requires more researches.
&Use of artificial intelligence in Blockchain-based healthcare networks: As Blockchain-
based healthcare systems are growing exponentially; analyzing data in this area will
become increasingly difficult. Using artificial intelligence and machine learning can make
it easier to parse and analyze data in this area.
9 Conclusion and limitation
This review provided a systematic review of the existing Blockchain-based approaches that
tried to preserve privacy and security in healthcare. At first, Blockchain and its characteristics
were defined, and then the electronic health records and the role that Blockchain can play in
maintaining security and privacy in this area were examined. We selected and reviewed recent
papers from valid scientific databases. The advantages and disadvantages of using Blockchain
in healthcare compared to traditional methods were mentioned. After applying the mentioned
query, 331 journal papers and 156 conference papers were found in all of the above-mentioned
databases. Finally, we selected 51 papers published between 2018 and December 2022
according to the mentioned paper selection process. We discussed the main idea, evaluation
metrics, and tools or framework, and type of Blockchain used in each selected paper.
Evaluation metrics such as integrity (in 10% of papers), access control (in 8% of papers),
security (in 25% of papers), privacy (in 17% of papers), availability (in 6% of papers), latency
(in 4% of papers), scalability (in 10% of papers), performance (in 16% of papers) and cost (in
4% of papers) were used in the reviewed papers. Regarding the type of Blockchain used in the
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papers, it was observed that 35% of the reviewed papers used private Blockchain, 10% used
hybrid Blockchain, 43% used public Blockchain and 12% used consortium Blockchain.
Regarding the limitations of this paper, we can mention the non-use of conference papers.
Conference papers can sometimes contain interesting and innovative materials. In this paper,
seven research questions were mentioned and answered, while other researchers may consider
additional questions. Also in this review paper, six valid scientific databases were used to
search for papers, while other valid scientific databases were also available for search. In this
paper, only international journals have been used and national and domestic journals have
been omitted. Moreover, non-English papers and book chapters were not used. Finally, this
paper reviewed papers that were published between 2018 and August 2022, and papers that
were published before 2018 were not reviewed.
Data availability Data sharing not applicable to this article as no datasets were generated or analyzed during the
current study.
Declarations
Conflict of interest The authors declare that there is no conflict of interest.
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