MedBlock: Using Blockchain in Health

Healthcare Application based on Blockchain and Smart Contracts

Maria Inês da Fonseca Ribeiro and André Vasconcelos

INESC-ID, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal

Keywords: Healthcare, Interoperability, Blockchain, Smart Contracts, MedBlock, MedClick.

Abstract: Nowadays, healthcare data is generated every day from both medical institutions and individuals. Store and

share such large amounts of data is expensive, challenging as well as critical. This challenge leads to a scenario

of a lack of interoperability between health institutions and consequently to a patient's health data scattered

across numerous systems. Blockchain emerges as a solution to these problems. It consists of a distributed

database where records are saved with cryptographic encryption, making them immutable, transparent and

decentralized. There are multiple healthcare applications blockchain-based that are being actively developed

in order to solve the problem of interoperability between different health providers. The main objective of

this work is to analyse and survey the blockchain technology and to study the smart contracts development,

for the purpose of healthcare applications. Since this research is developed in the context of MedClick – a

web platform that has the goal to give patients the possibility to save their health data plus interact with all

the medical institutions they choose to, in one single site – an additional goal of this paper is to set the

architecture to MedBlock – the MedClick platform based on blockchain and smart contracts.

1 INTRODUCTION

In our society, healthcare is a domain where a large

amount of data is generated, accessed, and

disseminated on a regular basis. Storing and

distributing this large amount of data is crucial, as

well as significantly challenging, due to the sensitive

nature of data.

Furthermore, the healthcare interoperability

landscape is generally centered around business

entities, like hospitals and clinics. Each entity, creates

and maintains data with its own format and it is siloed

within the information system that creates it. Because

of this business centered scenario, a patient is also

obligated to fully trust his or her Electronic Health

Record (EHR), that contains highly sensitive and

critical data, to certain institutions. Besides, when

needed, the exchange of patients’ data between

different institutions can be technically challenging

and requires significant collaboration between the

entities involved (Gordon & Catalin, 2019).

The consequence of the lack of interoperability

between entities is that an individual patient's health

data may be scattered across numerous systems, and

no institution may have a complete picture. This

causes

a lack of patient centricity and can lead to a

compromised treatment (Medicalchain, 2018).

A technology that has been growing and

expanding is the blockchain technology. Succinctly,

this technology consists in a distributed database. Its

records are saved in blocks which makes it an

immutable, secure database. Being decentralized

allows its transactions to be transparent. This

emerging technology is being developed in many

different sectors, including healthcare.

Using blockchain, the problem of the lack of

interoperability between different health providers

can be solved, lowering operations costs and

coordination efforts. Besides, patients’ health records

integrity is ensured and allows them to own their

private health records.

Considering the need to come up with a solution to

develop healthcare applications capable of handling

healthcare information at an increasing scale, capable

of sharing patients health records between different

institutions, increasing interoperability, the main goal

of this work is to survey the state of the art of

blockchain technology, its principles and applications

and how smart contracts can complement it.

Furthermore, this paper aims to survey the state of the

art of healthcare applications based on blockchain.

Since this study is done in the context of MedClick

156

Ribeiro, M. and Vasconcelos, A.

MedBlock: Using Blockchain in Health Healthcare Application based on Blockchain and Smart Contracts.

DOI: 10.5220/0009417101560164

In Proceedings of the 22nd International Conference on Enterprise Information Systems (ICEIS 2020) - Volume 1, pages 156-164

ISBN: 978-989-758-423-7

(a web platform that aims to give patients the

possibility to schedule appointments, interact with all

health providers and manage healthcare information

in one single site), an additional goal of this work is

to implement MedBlock – the MedClick platform

based on blockchain and smart contracts.

The rest of this document is organized as follows.

In Section 2, the related work is presented, including

the background and state of the art of blockchain and

smart contracts, its application in healthcare and an

analysis of existing blockchain applications that focus

on healthcare. In Section 3, the proposed solution is

described, as well as its requirements and the work

already implemented. In Section 4, the evaluation

methodology to analyse the proposed solution is

defined. Finally, Section 5 concludes this document.

2 RELATED WORK

This section first describes how blockchain works and

its main components. Then, a few blockchain

platforms are analyzed. Next, the benefits of

blockchain in healthcare are explained. Lastly,

existing works that refer to healthcare platforms

based on blockchain are presented.

2.1 Blockchain Background

2.1.1 Distributed Ledger

A possible technology to solve the lack of

interoperability among health institutions and to solve

the lack of patient centricity is the distributed ledger.

A distributed ledger is an asset database that can

be shared across a network of multiple sites or

institutions. This network is composed by

participating nodes or peers, where each peer is a

computing device. All participants nodes can have

their own identical copy of the ledger. Besides

sharing assets, the participants nodes can have

resources allocated, that when functioning together

can make decisions on behalf of the network

(Leeming, Cunningham, Ainsworth, 2019). This

technology is highly efficient since changes made by

any participant with the permission are immediately

reflected in all copies of the ledger. (Gupta, 2018).

2.1.2 Blockchain Network

Blockchain is one form of a distributed ledger.

This specific shared ledger has records saved in

blocks that are linked together creating a chain. This

means the records saved have an order. In its turn,

each block consists of a group of transactions and a

hash that binds it to the preceding block (Li, Nelson,

Malin, Chen, 2019).

This type of distributed ledger is defined as an

immutable ledger for recording transactions, because

no participant node can tamper a transaction after it

has been recorded to the ledger. (Gupta, 2018).

Besides being a type of database, blockchain can

also set rules about a transaction and tied them to the

transaction itself. In contrast with conventional

databases where the rules are set at the database level,

not in the transaction (Walport, 2016).

An important aspect to mention is that, in

practice, blockchain may not be a suitable technology

to store large amounts of data due to the cost and

speed of writing data. A solution to this problem is to

store the actual data off-chain, in external data

sources, and store on-chain the pointers to that data as

hashes (Leeming, Cunningham, Ainsworth, 2019).

This design continues to guarantee the integrity of

data by comparing the hashes off and on-chain.

2.1.3 Smart Contract

Smart Contracts are computer programs written to

form agreements or establish a set of rules between

participants in a blockchain network. Using smart

contracts it is possible to ensure that the clauses of a

contract are accomplished and that breaching the

contract is expensive (Rosado, 2018).

Smart contracts are stored in the blockchain

network and are executed automatically as part of a

transaction, without relying on a third party (Gupta,

2018). This means that when a participant node

receives a transaction, the smart contract associated

with that transaction is invoked to ensure the validity

of the transaction and that the conditions stated in the

contract are met (Rosado, 2018). The result of the

transaction, if valid, is then recorded in the

blockchain. They cryptographically assure business

logic, provide controlled access to the blockchain and

allow that a transaction over an asset is made in a

transparent, conflict-free way while avoiding

transaction costs and the interference of a third party

(Swanson, 2015).

There is a variety of smart contract use cases that

can be applied to different application domains. They

can be used for banking transactions, for registering

any kind of ownership, or managing access control to

a specific asset. In each case, the smart contract

includes all the terms and conditions agreed by each

stakeholder available in the respective process.

The existence of smart contracts makes it possible

to create decentralized applications based on

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157

blockchain technology. Putting it simple: if the

blockchain is the database, then the smart contract is

the application layer that accesses it.

2.1.4 Permissioned and Permissionless

Blockchain

Blockchain networks can be permissioned or

permissionless.

Permissioned networks are private. This means

users need credentials – a unique identity – to connect

to the network and have restricted levels of access.

Within these networks there is a main identity

provider that manages access control (Li, Nelson,

Malin, Chen, 2019). These types of networks are

more suitable for organizations that want the ability

to constrain network participation. This leads to a lack

of transparency which is a disadvantage, but it

compensates assuring confidentiality.

On the other hand, permissionless networks are

public. This means they are accessible to every

Internet user and do not need credentials to add new

blocks to the distributed ledger. Any machine can

become a trusted node in the network, have an

identical copy of it and participate in it (Li, Nelson,

Malin, Chen, 2019). These types of networks

typically involve a native cryptocurrency

(Androulaki et al, 2018).

2.1.5 Consensus Mechanism

A consensus mechanism is the process in which a

majority of network participants come to an

agreement on the state of a ledger. It is a set of rules

and procedures that allows to add blocks to the

blockchain and maintain coherent a set of facts

between multiple participating nodes (Rosado, 2018).

There are several mechanisms that vary from

blockchain to blockchain. Table 1 presents a

description of the most used.

2.2 Blockchain Platforms

Blockchain emerged with the creation of the Bitcoin

blockchain in 2009. Bitcoin was developed as a peer-

to-peer electronic cash system and its goal was to

develop electronic payment system based on

cryptographic proof, allowing a transaction to happen

without trusting a third party (Nakamoto, 2008).

After that, there has been an increase interest on

the development of blockchain-based technologies

and blockchain capabilities started to be considered to

improve existing applications and to develop new

ones. This happen not only in financial sectors, but

also

in governments, supply services, insurances,

Table 1: Table with the most used consensus mechanisms.

Consensus Description

Proof of

Work –

PoW

Requires nodes to spend large amount of

computational power to solve intensive hashing

algorithms to add a new block. PoW gives

economic incentives to participating nodes so

they spend their computational power (Li,

Nelson, Malin, Chen, 2019)

Proof of

Stake –

PoS

Has miners that stake their cryptocurrency

tokens as a bet on which block they want to

include in the ledger. This proof makes it so that

any participant of the network has in its best

interest to be honest. This mechanism is less

wasteful than PoW (Costa, 2018)

Proof of

Authority

– PoA

The transactions are validated, aggregated into

blocks and put into the blockchain by approved

known nodes, which act like administrators.

This is a more centralized kind of consensus (Li,

Nelson, Malin, Chen, 2019)

Byzantine

Fault

Tolerance

– BFT

There are numerous BFT algorithms and they

require each node to know every other node in

the network so that consensus is reached. They

normally require a trusted central authority.

commercial services and healthcare.

Besides, blockchain platforms started to appear to

allow developers to develop blockchain applications

at ease. There are a variety of platforms for a diversity

of business needs that allow more companies to

implement their blockchain-based business.

At the moment, Ethereum and Hyperledger Fabric

are the most relevant blockchain platforms due to

their features (Kuo, Rojas, Ohno-Machado, 2019).

Considering network permission, consensus protocol,

smart contracts support and scripting language as

main features, it is possible to compare the two

platforms to choose the platform that can be used for

the proposed solution of this work.

Ethereum can be a permissioned or

permissionless blockchain, uses the Proof-of-Work

consensus and allows the development of smart

contracts in Solidity, a domain-specific language. It

has a public cryptocurrency that is used to mining,

that is, to add new blocks to the network. Hyperledger

Fabric is a permissioned blockchain, its consensus

algorithm is pluggable, depending on the domain it is

being used, and supports smart contracts in Java, Go

and Node.js. Also, Hyperledger Fabric does not have

cryptocurrency (Kuo, Rojas, Ohno-Machado, 2019).

When comparing these platforms in terms of their

technical features, Hyperledger Fabric is most

suitable for the purpose of this work. This is because

it supports smart contracts in popular languages that

most developers know, it has a modular and

pluggable architecture that makes it more versatile to

implement and does not have a cryptocurrency that

makes the consensus computationally expensive.

These features meet the requirements for the solution

that will be proposed below.

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2.3 Blockchain in Healthcare

Healthcare is one sector where blockchain technology

can make a difference and have an impact in patient’s

lives.

In this sector, all clinical data transactions have

verification costs associated. There is the cost of

securing data, along with the cost of maintaining a

primary source of truth (Gordon & Catalini, 2018).

Moreover, a result of the current healthcare being

centered around business entities is the use of highly

centralized information technology systems.

Blockchain is one possible technology that can

mitigate this problem. It is economical and efficient

and being a decentralized ledger, it eliminates

duplication of effort and reduces the need for

intermediaries (Gupta, 2018). Additionally, applying

blockchain to medical platforms may lower

operations costs and coordination efforts to reach

interoperability at scale (Gordon & Catalini, 2018).

This secure interoperability between health

providers is assisted by smart contracts, since once

set, a smart contract is immutable and can be trusted

to operate the same way, using trusted information

shared equally between all entities, indefinitely

(Kumar, Ahmad, Ramadi, Braeken, 2018).

By design, permissioned distributed ledger

systems are more compatible with healthcare systems

and therefore provide more utility to medical

institutions (Underwood, 2016). This is due to the

need of selective disclosure of private information

that rely on zero knowledge cryptography to provide

verification of transactions with a high degree of

privacy over the data (Gordon & Catalini, 2018).

2.4 Blockchain Implementations in

Healthcare

Regarding the development of blockchain in

healthcare, there are currently several papers and

implementations.

A relevant example is the Estonian Government

that implemented a blockchain solution in 2012

where each person in Estonia has an online e-Health

record that can be tracked. The KSI Blockchain

technology is used. Because only a hash of data is

stored on the blockchain, it can scale to provide im-

-mutability at high speed (Martinson, 2019).

Another example is the Ledger of Me platform

where the access of medical data and digital

interventions is combined. It is a system that allows

apps to interact with patients and their data. This

platform does not store EHR directly on the

blockchain, instead it stores hashes in it that will work

as pointers to the EHR stored off-chain (Leeming,

Cunningham, Ainsworth, 2019).

Similarly, the MediBchain paper proposes a

patient centric healthcare data management system by

using blockchain as storage to guarantee privacy.

Here the patient’s data is also shared and managed by

him (Omar, Rahman, Basu, Kiyomoto, 2017).

Likewise, CareChain is a consortium that

establishes a blockchain to which everyone can

connect but not be a computer node. It aims to create

interoperable health data blockchains and to give

individuals control over their own health information

(Carechain).

Another example of a system that is blockchain

based and will permit patients to easily and securely

share their medical records with providers is the

Coral Health platform. Its goal, using Ethereum, is to

create efficiencies in small but multiple parts of the

current health data landscape (Park et al, 2018).

Dovetail Lab is as well working on a healthcare

system to share patient’s data to improve the overall

healthcare system and healthcare services. The

system, based on Hyperledger Fabric, always informs

patients about data sharing and never do this without

the correct permissions (Dovetail, 2019).

MyMEDIS is also a blockchain-supported system

that, using both Fabric and Ethereum, aspires to give

control to patients over their existing medical records

and health related data, while making them instantly

available everywhere (Kovach & Ronai, 2018).

A blockchain infrastructure that implements its

own blockchain platform, that is, it does not use

blockchain platforms like Ethereum or Hyperledger

is Patientory. Its goal is to empower patients,

professionals, and healthcare providers to access,

store and transfer information safely, thus improving

care coordination while ensuring data security

(McFarlane, Beer, Brown, Prendergast, 2017).

Another identical proposal is the BlocHIE paper.

It suggests a blockchain-based platform for

healthcare information exchange between medical

institutions and individuals. It uses two loosely-

coupled blockchains

– Electronic Medical Records

Chain that stores EMR for medical institutions and

Personal Healthcare Data Chain that stores PHD for

individuals (Jiang et al, 2018).

MedRec is also a proposal of a decentralized re-

cord management system to handle EHR and its

implementation is based on Ethereum. It has a

modular design that integrates with providers'

existing data storage solutions (Azaria, Ekblaw,

Vieira, Lippman, 2016).

One more example is the Medicalchain platform,

built on Hyperledger Fabric. This platform allows

MedBlock: Using Blockchain in Health Healthcare Application based on Blockchain and Smart Contracts

159

other digital health applications to develop on. It is

currently developing two applications: a telemedicine

to consult a doctor remotely and a marketplace of

health record to use in research. It uses two

blockchain structures – Hyperledger Fabric and

Ethereum (Medicalchain, 2018).

The majority of the solutions presented focus on

the benefit of blockchain to provide an audit of access

to data to allow the patient to manage consent and to

provide interoperability between several institutions.

Thus, this work is based on existing works, that is, it

is the combination of specific elements of each work

in order to develop a use case of a healthcare

application – MedBlock, the MedClick platform on

blockchain and smart contracts.

Table 2: Table comparing related work mentioned above.

Technology Consensus Cryptocurrency

Estonian

Government

KSI Block-

chain

Not specified No

Ledger of Me

Available to use

different

technologies

Not specified No

MediBchain

Own

Technology

Own protocol No

Carechain

Ethereum

without mining

Not specified Yes

Coral Health Ethereum PoW

Coral Health

Tokens

Dovetail Lab Fabric Practical BFT No

BlocHIE

EMR-Chain +

PHD-Chain

PoW with

FAIR-FIRST

+ TP&FAIR

MedRec Ethereum PoW No

Medical-chain

Fabric +

Ethereum

Practical BFT

+ PoW

MedTokens

MyMEDIS

Fabric +

Ethereum

Practical BFT

+ PoW

MediCoin

Patientory Ethereum PoW PTY/ DASH

3 PROPOSED SOLUTION

This section describes the proposed solution, its

requirements and architecture.

3.1 Requirements

In order to develop MedBlock, the healthcare

application proposed in this paper, it is necessary to

consider the requirements of MedClick.

MedClick is a one-stop platform that allows to

book an appointment across multiple medical service

providers, in a fast and user-friendly way. By having

a single platform for the patient to access multiple

healthcare providers, booking a medical consultation

becomes simpler and quicker. This allows the patient

to avoid the tedious and complicated process of

booking an appointment and always be dependent of

the electronic system provided by each health

provider. Figure 1 presents a UML Use Case diagram

with the most relevant use cases of the MedClick

platform that this work is expected to support.

Figure 1: Use Case diagram of the MedClick platform.

Figure 2: Business process for booking an appointment in

the MedClick platform.

Figure 3: Business process for browsing information in the

MedClick platform.

In Figure 2 and 3, it is represented the business

processes, in BPMN, regarding the most relevant

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functionalities for the purpose of this work – book

appointment and browse information.

3.2 Solution

Considering the distributed context of interaction

with medical institutions, involving several

healthcare providers, patients, and insurances, and the

current architecture of the MedClick platform, a

solution to help improve interoperability, security,

shareability and accessibility of health data is to

implement MedBlock – the MedClick platform based

on blockchain and smart contracts.

The main goal of this solution is to save

information in the blockchain regarding

appointments, patients’ most relevant information,

health professionals, health providers and insurances.

Additionally, all transactions about this

information are also stored in the blockchain so that

these become immutable and visible to all authorized

entities. In Figure 4, it is represented an Application

Usage Viewpoint in Archimate of the main features

of the MedBlock and the interaction of those

authorized entities with the blockchain. The Other

Ledgers mentioned can correspond to more

Healthcare Providers.

Concerning the patient’s health records, that differ

from the patient relevant information in terms of size

and quantity, they are saved outside the blockchain in

a non-distributed way. Moreover, a hash of each

health record, used as a pointer, is stored in the

blockchain. This design avoids the expensive

computational cost of storing large files in the

blockchain, while assuring that the data is not

changed without permission. This guarantee is made

through the comparison of hashes off and on

blockchain.

Considering the granular access control required

for sensitive health data, the most suitable blockchain

is a permissioned and private one. Here most of the

blockchain control is given to MedClick, that has

access to all data. This allows that each health

provider has only access to data from their patients.

This configuration ensures confidentiality of data.

In Figure 5, it is represented a UML sequence

diagram of how a generic interaction between a

patient and the MedBlock ClientApp is, using

Hyperledger Fabric. Note that the MedBlock

ClientApp includes the MedClick portal and the

Node.js server. This server invokes the smart contract

– chaincode – created for MedBlock, that in its turn

communicates with the ledgers.

Regarding the requirements of MedClick

mentioned

above,

this

proposal

supports

the

flow

Figure 4: Archimate Application Usage Viewpoint of the

proposed solution.

Figure 5: UML Sequence Diagram of a generic interaction

with MedBlock.

booking an appointment and browsing information

regarding health providers, health professionals,

health insurances, locations or specialties. The smart

contract, that in Figure 5 corresponds to

proposeTransaction, includes one function for the

book appointment and another for browsing

information.

Taking in consideration the characteristics of the

proposed solution, the supported flows and

considering the reference of multiple existing works

already presented, Hyperledger Fabric, with Practical

Byzantine Fault-Tolerant consensus algorithm, is the

most suitable blockchain platform to implement this

solution. This choice is due to the fact that Fabric

supports smart contracts in Node.js which is the

language used in MedClick, it has a modular and

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161

pluggable architecture that makes it more versatile to

implement and does not have a cryptocurrency that

makes the consensus computationally expensive.

In figure 6, it is shown a Technology Usage

Viewpoint in Archimate, which is an example of a set

of nodes for the MedBlock Network and for a

Healthcare Provider, using Hyperledger Fabric. The

number and the type of the peers in each network can

be specified. This is an example for only one

Healthcare Provider, though the architecture for

several Healthcare Providers is the same structure.

Figure 6: Archimate Technology Usage Viewpoint of the

proposed solution.

3.3 Implementation

Using Hyperledger Fabric, the main steps to

implement the proposed solution are:

 Create a blockchain network, including the peers. It

must be specified where these peers are created – in

MedBlock and in each healthcare provider;

 Create private channels between MedBlock and

healthcare providers – this allows confidentiality;

 Create a Hyperledger Fabric ClientApp. This is the

connection between the end user and the MedBlock

blockchain network;

 Integrate the MedClick website that already exists

with the ClientApp;

 Write smart contracts – chaincode – that are called

from the ClientApp and submit transactions to the

blockchain network.

At the time of writing this paper, a few steps of the

implementation of the proposed solution have begun

to be developed after installing the prerequisites and

downloaded the necessary samples and images from

Hyperledger Fabric. The first step was the creation of

the MedBlock blockchain network, specifying the

number and the type of the peers. Afterwards, an

initial chaincode was written in Node.js, to initiate the

MedBlock blockchain with a set of patients, health

professionals, health providers and appointments, and

to request simple queries – for example to get all

health professionals or to get appointments by patient

email. Then, a preliminary version of an Hyperledger

Fabric ClientApp was developed as a Command Line

Interface, where the input from the command line was

parsed to invoke the chaincode previously created.

This initial implementation will be improved and

will be used as a base to continue to develop the

remaining steps of the planned solution.

4 WORK EVALUATION

METHODOLOGY

Blockchain technology has its strengths as well as its

weaknesses. To analyse the proposed solution in the

context of the MedClick using Hyperledger Fabric

and considering the trade-off between its

performance and its limits, an evaluation

methodology must be defined.

The performance of a blockchain platform can be

affected by many variables such as transaction size,

block size, ordering service, network size and

topology of nodes in the network, the hardware on

which nodes run, the number of nodes and channels,

and the network dynamics (Hyperledger Working

Group, 2018). To measure the performance of Fabric,

the Hyperledger community is currently developing a

draft set of measures along with a corresponding

implementation of a benchmarking framework called

Hyperledger Caliper (Hyperledger Fabric, 2019). It

allows to measure the performance of Fabric given a

set of use cases. This tool can produce reports

containing various performance metrics such as

execution time, latency, resource consumption,

scalability and throughput (Pongnumkul,

Thajchayapong, Siripanpornchana, 2017).

To measure the performance of MedBlock, the

Hyperledger Caliper will be apply to the use cases in

the context of MedClick regarding different types of

patients, appointments, health providers and health

professionals.

5 CONCLUSIONS

Nowadays, with the increasing number of medical

services providers and consequently the number of

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appointments, with the lack of interoperability and

the lack of patient centricity that is adjacent to it,

comes the need to find a solution with a secure and

viable way to store healthcare data and process

transactions in this sector. This solution must be

capable of mitigating these difficulties and improve

usability for the patients as well for the professionals.

This is where blockchain comes in. Being a

technology that ensures immutable and secure

transactions, it becomes a possible resolution for the

health sectors. Considering these two major factors,

after analysing the state of the art of blockchain

technology and of smart contracts, this work presents

a healthcare application blockchain-based –

MedBlock – as a solution to mitigate such problems.

To summarize, this research combines the

blockchain features that are beneficial for healthcare

with the smart contracts strengths, within the context

of the MedClick. This result in a healthcare

application based on blockchain and smart contracts

that gives patients the possibility to save their health

data plus interact with all the health providers and

professionals they choose to, in one single platform.

Besides, being implemented in Hyperledger Fabric, a

blockchain platform that has a modular architecture,

allows this work to take advantage of the blockchain

strengths in a business development context.

Currently the authors are finishing the

implementation of MedBlock and the evaluation of

results is planned.

ACKNOWLEDGEMENTS

This work was supported by national funds through

Fundação para a Ciência e a Tecnologia (FCT) with

reference UIDB/50021/2020 and by the European

Commission program H2020 under the grant

agreement 822404 (project QualiChain). The authors

would like to thank MedClick and Rui Cruz for the

opportunity to be a part of this project.

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